Expansion valve bulb and / or equalizer tube located
on your gauge means the refrigerant will produce about 32F at the evaporator (as long as the orifice tube/expansion valve is operating properly and theres no air in the system thats artificially inflating the pressure to 27-psi). Place a temperature gauge in one of the air outlets in the passenger compartment. Refrigerants are the vital working fluids in refrigeration systems. is inconsistent. Flooded head pressure control: Hot gas bypass line
This will eliminate confusion regarding any leaks in the future. Before you make any determination regarding the pressure gauge readings, you need to consider the service port locations. or defective. Voltage out of balance on 3 phase systems. Flood back due to poor distribution of refrigerant
Free, one year (or more), unlimited mileage warranty. Low and High AC pressures are lower than recommended in an expansion valve system where the valve is located on the evaporator outlet. For further information on this method of leak detection, refer to the instructions provided with the dye. Here is a list of the pressure readings that are characteristic of an A/C compressor that is not blowing cold air into the cabin of your car: 250 PSI / 30 PSI = You have air somewhere in the system. The recovery unit will continue to operate, drawing in air from the leak source and adding it to the storage tank. In that case, you must fix that problem first. Both temperatures are usually needed to analyze system performance. 4. 
1. Diagnosis and Repair of Under Hood Components. So the refrigerant picks up too much heat. You will also want to check if the HVAC doors and the HVAC controls are working correctly. have a bleed resistor? Maintenance Advantage program. There should
calculations. Get the BEST auto repair information Alldatadiy.com and Eautorepair.net are professional-grade shop manualsperiod. youll need an AC manifold gauge set and hoses. Fans and blowers move fresh or recirculated air across the evaporator fins and heater core to provide heated air for the climate control system. Remember, these are the locations on the system where your gauges actually monitor the pressure. 
In most cases, their diagrams are right from the factory manuals. To clean the evaporator coil, use a foaming chemical cleaner. These charts give you pressure readings and possible causes to check to pinpoint the cause of the concern. Re-circulating of condenser air. Check the performance charts of
Expansion valve defective or held open by a foreign
A tool that can identify the contents of an A/C system is essential in some diagnostic situations. check the pressure dome settings. PAG oils have a high hygroscopicity, which means they readily absorb moisture and retain it much easier than mineral oil. The mixture should be 50/50. Available in the contiguous U.S. only. Flooded head pressure control: Incorrect control,
Many refrigerant leaks can be found through a simple visual inspection.
open. Uneven or inadequate evaporator loading due to A minimum of four should be used. You need to use these readings, other symptoms, the Service Manual and your knowledge of system operation to find the trouble with the system. An AC system leak allows moisture into the system. High supply voltage, light compressor load. improperly on the system. There are several PAG oils with special additive packages and different viscosities, which are used in current Nissan and Infiniti vehicles, depending on the type of compressor used. Generally speaking, you want around 27-psi on the low side and 200 on the high side. So, if you really want to diagnose and fix your AC system yourself. down controls and a crankcase heater.
Moisture in the system reacts with the refrigerant and oil to form acids and sludge that clog orifice tube screen Moisture in the system that freezes at the orifice tube and restricts refrigerant flow through the orifice. Electronic leak detectors must meet or exceed SAE J1627 to operate properly on R-134a. Partial load, low humidity, etc, without capacity Has there been a recent addition They include wiring diagrams and technical service bulletins. Evacuate the system and recharge with the correct refrigerant charge and test again. Turn on the leak detector. However, adding more than specified to the A/C system will not make the leaks more obvious. The equipment must be dedicated for the recovery of contaminated refrigerant only! If the recovery unit has a properly operating automatic purge, usually it will vent the excess air. To perform top-quality A/C work, you will need to know if a container of recycled refrigerant is tainted with air. The engine temperature gauge is normal, but I have no heat!. Compressor - Loss of oil, Loss of oil pressure, or Cuts off on oil pressure control. For example, if the high-side service port is located on the liquid tank and the hose between the condenser and the liquid tank is restricted, your gauge readings will be lower than you may expect. Compressor manufacturers are very concerned about the addition of lubricants other than those specified on the vehicles label. Look for heater hoses and either a cable or vacuum hoses running to a valve. Expansion valve defective or has the incorrect By reading the gauges alone, you may be misled into making an inaccurate diagnosis. 2.
Always tightly cap all PAG oil containers after each use. First, check the engines coolant level. Expansion valve or metering device too large. Excessive refrigerant on non receiver system. Buy a set or rent a set, just dont kid yourself into thinking you can make any kind of diagnosis without it. _gaq.push(['_setAccount', 'UA-4776845-1']); If your pressure gauge readings are not within factory specifications, there is a problem in the system. For More Free Troubleshooting Information Please Visit Our Home Page. If the coolant level is low, this may indicate that air is trapped in the heater core. Why 27-psi? Incorrect capacitor, capacitor voltage rating too Measure ambient air temperature at the vehicle and under the hood WITH A THERMOMETER (do not use weather service temperatures).
System contamination, probably moisture or rarely, Leakage can usually be traced to loose fittings, deteriorated hoses or seals, or damaged metal lines. Go to www.NNAnet.com and click on the Maintenance Advantage link. Read the pressure gauges and compare them to factory specifications. For vehicle specific information, refer to the appropriate Service Manual or the vehicles A/C decal.
If it does not, replace the batteries before proceeding.
The J-43926 Air Conditioning Dye Kit provides you with a method for adding trace dye to the A/C system. motor or a flooded head pressure control system. cycles. Check the rotation, Incorrect expansion valve power head charge. If the gauge reading goes back to a very low suction-side reading, the orifice tube or expansion valve screen is likely frozen. Too much oil will reduce the cooling capacity of the system. 1, Set the AC controls to MAX and RECIRCULATE 2. 225 PSI / 80 PSI = It is likely that the expansion valve is opened too wide (not the case if your A/C system has an orifice tube) Also, you could have too much refrigerant in the system. Use a hand pump vacuum to operate the valve or move the cable by hand to close it off. Drier/liquid tank). If the actuator moves but the air door doesnt try moving the door by hand. First, to properly diagnose AC pressures when the AC is running you MUST know what type of AC system youre working on. Uninsulated receiver in a cold ambient acting as Ask questions about past changes. Has the refrigerated space been increased in size? NOTE: Trace dye is mixed with the PAG lubrication oil. The leak detector may not operate effectively if any refrigerant has been released under the hood from gauge hook-up or charging.
When properly charged, a full evaporator will spill some boiling refrigerant into the accumulator where it will continue to vaporize before entering the compressor. During the visual inspection, be sure to check the service fittings after removing the gauges. warm, condenser tubes restricted or defective water regulating valve. Equipment with an automatic air purge usually keeps the air contamination level at less than 2 percent by weight, which is considered acceptable. Excessive suction pressure beyond the limits of of the evaporator will freeze up when this occurs.
Excessive pressure drop in the liquid line due
NOTE: Refer to the HA section in the ESM for the applicable vehicle for pressure readings at various ambient temperatures and the setting the AC should be on when diagnosing with pressure gauge readings. in the low side. External equalizer lines tapped at a common point Product, people, heat producing equipment in the compressor for the maximum suction pressure. A possibility exists that a small leak may occur without any signs of trace dye. System undersized.
The load is too high. If so, then check the low side although there is more than one expansion valve on the same system. Without refrigerant identification equipment, the refrigerant containing only air would not be saved because the actual problem could not be identified with Go/No-Go equipment. the condensing unit is mounted on the box and closed off by a drop Air can also be added during the refrigerant recovery process from system and service hose leaks. Low side pressure will increase to the point where the low-pressure switch activates the compressor. This may be accomplished with the vehicle service valve or a refrigerant container. Find the leak and fix before refilling. Usually corresponds with high superheat at the Low side pressure drops below low-pressure switch threshold, which shuts off the compressor. Fan cycle control: This is normal if this type caused by poor air distribution. Alldatadiy.com, on the other hand, uses the factory diagrams. using performance chart. hot gas bypass valve or capacity control valve. Damaged valves or rods in the compressor. the refrigerant entering the condenser will be around 130F. Liquid migration on the off cycle. Manual reset low or high pressure control lockout. Caution must be taken when flammable refrigerants have been detected, including the use of special air-powered recovery equipment. which creates the possibility of flooding on start up. However, recycling equipment with a manually operated purge can allow high levels of air into the system usually due to technician error. Eautorepair.net redraws factory wiring diagrams in color and includes the component, splice and ground locations right in their diagrams. There should be no more than 5 degrees If the low and high side gauges read the same pressures and the readings correlate to the pressures/temperatures shown on the chart above, they only tell you two things: If the static pressure is lower than 27-psi. If this is a problem, use low-pressure compressed air or a fan to blow any released refrigerant from the engine compartment before leak testing. This can be caused by a stuck air temperature door, faulty air temp/blend door actuator or, in older systems, a stuck open heater control valve thats running hot engine coolant into the heater core even though the heat is set to cold. If the refrigerant in a system contains excess air but has no other problem, removing the air will resolve a high pressure or loss of performance problem. 4. the lube oil control to time out and shut the system down. NOTE: High humidity and airflow velocity across the evaporator and condenser have a direct effect on pressure readings. This not only enables the system to operate efficiently but also ensures proper lubrication of the compressor. Many times the door can get stuck or break off from its hinges. There are also different types used in A/C service; therefore, it is very important that you use the correct type. Any time more than 0.5 lb. If the air is not removed from the system, the system will have performance problems. In other words, the low refrigerant charge causes the refrigerant is in the system to sit too long in the evaporator. After analysis is made and displayed, the analyzer purges the unit of the sampled refrigerant and is ready for the next sample. system where all the EPR valves are wide open. Air in the system. Probably in the evaporator. More importantly, the eyeglasses protect your eyes from damaging ultraviolet light. Keep in mind that AC works when the refrigerant removes just enough heat from the air to cause the refrigerant to change from a liquid to a vapor. Pricing: ---Eautorepair.net--- 1 month subscription $19.95 per vehicle 1-year subscription $29.95 per vehicle 4-year subscription $44.95 per vehicle ---Alldatadiy.com--- 1-year $29.95 subscription: additional vehicles $19/95 each 5-year $49.95 subscription: additional vehicles $34.95 each Which one should YOU choose? 250 PSI / 50 PSI = The system is overcharged and the condenser is not cooling. for a leak. of a Crankcase Pressure Regulator (CPR) or pressure limited TXV Finally, always attach the trace dye identification sticker in the engine compartment close to the A/C decal. Check for hose leaks and porous or worn tubing. Pressure or temperature control differential too This will enhance the luminescence of the dye, which will make the smaller leaks more apparent. a refrigerant distributor. Gauge readings may not always indicate the same pressure throughout the entire high side or low side of the system.
There are also a few techniques that will help confirm your suspicions regarding those pressure gauge readings. Expansion valve power element has failed or lost
If the cabin air temp is controlled by an air temp/blend door, check actuator operation to see if it moves as you change the temperature setting. If the container pressure is not checked, air will transfer into the system. NOTE: Too much dye can affect the viscosity of the refrigerant oil. document.getElementById( "ak_js" ).setAttribute( "value", ( new Date() ).getTime() ); Enter your email to receive an instant discount. Attach to the hoses and gauge set to the high and low side ports of your AC system. Consider all the factors, including ambient temperature, condenser airflow, engine rpm and humidity, which all affect the manifold gauge readings. This creates the possibility of flooding on start
To find a leak with an electronic leak detector: 1.
Symptom: Low cooling Pressure readings: Low side is low. Usually the bottom rows Shine an ultraviolet lamp on the A/C system and look for traces of dye, indicating leaks. Check amp draw verses suction pressure verses condensing temperature Flooded head pressure control: Power head has lost Copyright 2022 Buy Auto Parts. the header. The dye must circulate through the entire system before it will reach the source of the leak. Start winding staying in the circuit too long. While small leaks of a few ounces of refrigerant per year are difficult to detect, larger leaks of about a pound per year can easily be isolated. Yeah, its just like a furnace filter. Check the front of the AC condenser (its in front of the radiator) to make sure the fins arent clogged. discharge valve leaks. Insufficient refrigerant charge, usually accompanied Incorrect starting relay. controls are set incorrectly.
Un-insulated receiver exposed to low ambient. If the gauge reading is normal when first turned on and stays normal for a few minutes, you get cold air and THEN low side goes low, thats a sign of moisture in the system. That saves a lot of time because you dont have to refer back to the component locator or circuit locations. Check the performance variable speed motor or a flooded head pressure control system.
This is called superheat and in an orifice tube system, the superheated refrigerant is what causes evaporator icing. small.
Some of the more common types available today are identified by the following classifications: Each type has advantages and disadvantages, which is why it is so important to follow the manufacturers operating instructions. open due to a foreign material lodged in it, or the port is worn. If R-134a has not been identified as 98 percent pure, the vehicles A/C system should not be serviced with dedicated equipment. Turn off the A/C system and the vehicle. If there has been an oil loss for any reason, repair the cause of oil loss and refill according to the Refrigerant Oil Capacities chart in the Service Manual for the vehicle being serviced. port wedged open due to a foreign material lodged in it. with the compressor manufacturer. They are just a guide to aid you in your diagnosis. 125 PSI / 30 PSI = The system is either not charged enough or you have too much oil in the compressor. Fan cycle control: This is normal if this type Depending on the symptoms, there are various reasons your customers heater might not be working. control. Oil, stains or dirt are good indications of a leak. material causing liquid flood back. occurrence when an oversized outdoor weather hood has been installed. The system pressure is high enough to enable compressor clutch engagement. To perform the leak test, the system must be under pressure. Flooded head pressure control: Bypass condenser Synthetic-based PAG oils are used with R-134a systems.
So you have to refer to the factory legends to learn the identification symbols and then refer back to circuit diagrams to find the splice and ground locations. 3. Using a Go/No-Go refrigerant detector for both service situations can only identify system contamination. Always refer to the manufacturers instructions for proper use of the refrigerant analyzer. Defective oil pump or the oil pump inlet screen This may be a situation where the AC is working fine but the heat is on, diminishing the effects of the AC. Worn bearings, cylinder walls and piston rings conditions. For more information on Interpreting AC Pressure Readings, check out our How To page on the subject. unit. The compressor will shut off once the low pressure triggers the low-pressure switch. The moisture travels with the refrigerant. A compressor overheating will break down the wiring connections. Low outside air temperature on an air cooled system. OR, continue driving the vehicle with the blower on HIGH while monitoring airflow from the vents. Look, I know you want to figure out your AC problem yourself without buying any tools, but you can really screw up your cars AC if you overcharge or undercharge the system.
NOTE: All Nissan vehicles are originally built with refrigerant trace dye (usually a pellet placed in the Rec.
Does the start capacitor Because, on an R-134a AC system, 27-psi.
NOTE: Always wear the protective eyeglasses that come with your black light equipment. THEN, the gas absorbs even more heat from the evaporator airflow, causing evaporator temperature to fall below the freezing point of water. 150 PSI / 30 PSI = There is water in the system. Dont skip this part. With the engine OFF for at least 30 minutes, read the low and high-pressure gauges. Flooded head pressure control: Receiver too small is restricted or shut off.
Covers everything; parts and shipping costs. Thats an indication of a bad compressor. Excessive liquid refrigerant returning to the compressor 1. To test for evaporator freezing, turn off the engine and leave the vehicle for a while. WARNING: Ambient temp is the temperature at the vehicle under the hood, NOT THE WEATHER SERVICE. Recovery/recycling equipment that has a manual air purge should be checked every day before the recycled refrigerant is used. Existing low ambient controls out of adjustment if the system pressure returns to normal once youve applied heat to the orifice tube, the cause may be moisture in the system. As you go over the system, using the black light to check for indications of trace dye, do not forget to check the evaporator condensate drain. The electronic leak detector is a portable, electronic gas detector. ceiling. break down of the insulation between the terminals and the compressor Faulty low pressure control, temperature control, If the detected gas contains a hydrocarbon (flammable material), the unit sounds an alarm and displays HC. Poor distribution of refrigerant thru the evaporator If your static pressure readings dont match the temp/pressure chart and are too high (most common) these are the likely causes: The entire AC system is empty due to a major leak. If the center pulley isnt turning, see this post for diagnostics. This will leave refrigerant in the low side However, if the system is low on charge, the evaporator is only partially filled with refrigerant, so half of it will be cold and the other half hot. })(); Oil trapping in the system. to an undersized liquid line or excessive vertical lift. Check the evaporator, piping, and expansion valve to locate the source of the issue. See this post to learn what type of AC system is in your vehicle.
During the black light inspection if signs of trace dye were evident and the leak source was repaired, you would need to clean the area using the appropriate trace dye cleaning solution. The tool may also be required for A/C service centers according to regulations in your area.
1. Diagnosis and Repair of Under Hood Components. So the refrigerant picks up too much heat. You will also want to check if the HVAC doors and the HVAC controls are working correctly. have a bleed resistor? Maintenance Advantage program. There should
calculations. Get the BEST auto repair information Alldatadiy.com and Eautorepair.net are professional-grade shop manualsperiod. youll need an AC manifold gauge set and hoses. Fans and blowers move fresh or recirculated air across the evaporator fins and heater core to provide heated air for the climate control system. Remember, these are the locations on the system where your gauges actually monitor the pressure. In most cases, their diagrams are right from the factory manuals. To clean the evaporator coil, use a foaming chemical cleaner. These charts give you pressure readings and possible causes to check to pinpoint the cause of the concern. Re-circulating of condenser air. Check the performance charts of
Expansion valve defective or held open by a foreign
A tool that can identify the contents of an A/C system is essential in some diagnostic situations. check the pressure dome settings. PAG oils have a high hygroscopicity, which means they readily absorb moisture and retain it much easier than mineral oil. The mixture should be 50/50. Available in the contiguous U.S. only. Flooded head pressure control: Incorrect control,
Many refrigerant leaks can be found through a simple visual inspection. open. Uneven or inadequate evaporator loading due to A minimum of four should be used. You need to use these readings, other symptoms, the Service Manual and your knowledge of system operation to find the trouble with the system. An AC system leak allows moisture into the system. High supply voltage, light compressor load. improperly on the system. There are several PAG oils with special additive packages and different viscosities, which are used in current Nissan and Infiniti vehicles, depending on the type of compressor used. Generally speaking, you want around 27-psi on the low side and 200 on the high side. So, if you really want to diagnose and fix your AC system yourself. down controls and a crankcase heater.
Moisture in the system reacts with the refrigerant and oil to form acids and sludge that clog orifice tube screen Moisture in the system that freezes at the orifice tube and restricts refrigerant flow through the orifice. Electronic leak detectors must meet or exceed SAE J1627 to operate properly on R-134a. Partial load, low humidity, etc, without capacity Has there been a recent addition They include wiring diagrams and technical service bulletins. Evacuate the system and recharge with the correct refrigerant charge and test again. Turn on the leak detector. However, adding more than specified to the A/C system will not make the leaks more obvious. The equipment must be dedicated for the recovery of contaminated refrigerant only! If the recovery unit has a properly operating automatic purge, usually it will vent the excess air. To perform top-quality A/C work, you will need to know if a container of recycled refrigerant is tainted with air. The engine temperature gauge is normal, but I have no heat!. Compressor - Loss of oil, Loss of oil pressure, or Cuts off on oil pressure control. For example, if the high-side service port is located on the liquid tank and the hose between the condenser and the liquid tank is restricted, your gauge readings will be lower than you may expect. Compressor manufacturers are very concerned about the addition of lubricants other than those specified on the vehicles label. Look for heater hoses and either a cable or vacuum hoses running to a valve. Expansion valve defective or has the incorrect By reading the gauges alone, you may be misled into making an inaccurate diagnosis. 2.
Always tightly cap all PAG oil containers after each use. First, check the engines coolant level. Expansion valve or metering device too large. Excessive refrigerant on non receiver system. Buy a set or rent a set, just dont kid yourself into thinking you can make any kind of diagnosis without it. _gaq.push(['_setAccount', 'UA-4776845-1']); If your pressure gauge readings are not within factory specifications, there is a problem in the system. For More Free Troubleshooting Information Please Visit Our Home Page. If the coolant level is low, this may indicate that air is trapped in the heater core. Why 27-psi? Incorrect capacitor, capacitor voltage rating too Measure ambient air temperature at the vehicle and under the hood WITH A THERMOMETER (do not use weather service temperatures).
System contamination, probably moisture or rarely, Leakage can usually be traced to loose fittings, deteriorated hoses or seals, or damaged metal lines. Go to www.NNAnet.com and click on the Maintenance Advantage link. Read the pressure gauges and compare them to factory specifications. For vehicle specific information, refer to the appropriate Service Manual or the vehicles A/C decal.
If it does not, replace the batteries before proceeding.
The J-43926 Air Conditioning Dye Kit provides you with a method for adding trace dye to the A/C system. motor or a flooded head pressure control system. cycles. Check the rotation, Incorrect expansion valve power head charge. If the gauge reading goes back to a very low suction-side reading, the orifice tube or expansion valve screen is likely frozen. Too much oil will reduce the cooling capacity of the system. 1, Set the AC controls to MAX and RECIRCULATE 2. 225 PSI / 80 PSI = It is likely that the expansion valve is opened too wide (not the case if your A/C system has an orifice tube) Also, you could have too much refrigerant in the system. Use a hand pump vacuum to operate the valve or move the cable by hand to close it off. Drier/liquid tank). If the actuator moves but the air door doesnt try moving the door by hand. First, to properly diagnose AC pressures when the AC is running you MUST know what type of AC system youre working on. Uninsulated receiver in a cold ambient acting as Ask questions about past changes. Has the refrigerated space been increased in size? NOTE: Trace dye is mixed with the PAG lubrication oil. The leak detector may not operate effectively if any refrigerant has been released under the hood from gauge hook-up or charging.
When properly charged, a full evaporator will spill some boiling refrigerant into the accumulator where it will continue to vaporize before entering the compressor. During the visual inspection, be sure to check the service fittings after removing the gauges. warm, condenser tubes restricted or defective water regulating valve. Equipment with an automatic air purge usually keeps the air contamination level at less than 2 percent by weight, which is considered acceptable. Excessive suction pressure beyond the limits of of the evaporator will freeze up when this occurs.
Excessive pressure drop in the liquid line due
NOTE: Refer to the HA section in the ESM for the applicable vehicle for pressure readings at various ambient temperatures and the setting the AC should be on when diagnosing with pressure gauge readings. in the low side. External equalizer lines tapped at a common point Product, people, heat producing equipment in the compressor for the maximum suction pressure. A possibility exists that a small leak may occur without any signs of trace dye. System undersized.
The load is too high. If so, then check the low side although there is more than one expansion valve on the same system. Without refrigerant identification equipment, the refrigerant containing only air would not be saved because the actual problem could not be identified with Go/No-Go equipment. the condensing unit is mounted on the box and closed off by a drop Air can also be added during the refrigerant recovery process from system and service hose leaks. Low side pressure will increase to the point where the low-pressure switch activates the compressor. This may be accomplished with the vehicle service valve or a refrigerant container. Find the leak and fix before refilling. Usually corresponds with high superheat at the Low side pressure drops below low-pressure switch threshold, which shuts off the compressor. Fan cycle control: This is normal if this type caused by poor air distribution. Alldatadiy.com, on the other hand, uses the factory diagrams. using performance chart. hot gas bypass valve or capacity control valve. Damaged valves or rods in the compressor. the refrigerant entering the condenser will be around 130F. Liquid migration on the off cycle. Manual reset low or high pressure control lockout. Caution must be taken when flammable refrigerants have been detected, including the use of special air-powered recovery equipment. which creates the possibility of flooding on start up. However, recycling equipment with a manually operated purge can allow high levels of air into the system usually due to technician error. Eautorepair.net redraws factory wiring diagrams in color and includes the component, splice and ground locations right in their diagrams. There should be no more than 5 degrees If the low and high side gauges read the same pressures and the readings correlate to the pressures/temperatures shown on the chart above, they only tell you two things: If the static pressure is lower than 27-psi. If this is a problem, use low-pressure compressed air or a fan to blow any released refrigerant from the engine compartment before leak testing. This can be caused by a stuck air temperature door, faulty air temp/blend door actuator or, in older systems, a stuck open heater control valve thats running hot engine coolant into the heater core even though the heat is set to cold. If the refrigerant in a system contains excess air but has no other problem, removing the air will resolve a high pressure or loss of performance problem. 4. the lube oil control to time out and shut the system down. NOTE: High humidity and airflow velocity across the evaporator and condenser have a direct effect on pressure readings. This not only enables the system to operate efficiently but also ensures proper lubrication of the compressor. Many times the door can get stuck or break off from its hinges. There are also different types used in A/C service; therefore, it is very important that you use the correct type. Any time more than 0.5 lb. If the air is not removed from the system, the system will have performance problems. In other words, the low refrigerant charge causes the refrigerant is in the system to sit too long in the evaporator. After analysis is made and displayed, the analyzer purges the unit of the sampled refrigerant and is ready for the next sample. system where all the EPR valves are wide open. Air in the system. Probably in the evaporator. More importantly, the eyeglasses protect your eyes from damaging ultraviolet light. Keep in mind that AC works when the refrigerant removes just enough heat from the air to cause the refrigerant to change from a liquid to a vapor. Pricing: ---Eautorepair.net--- 1 month subscription $19.95 per vehicle 1-year subscription $29.95 per vehicle 4-year subscription $44.95 per vehicle ---Alldatadiy.com--- 1-year $29.95 subscription: additional vehicles $19/95 each 5-year $49.95 subscription: additional vehicles $34.95 each Which one should YOU choose? 250 PSI / 50 PSI = The system is overcharged and the condenser is not cooling. for a leak. of a Crankcase Pressure Regulator (CPR) or pressure limited TXV Finally, always attach the trace dye identification sticker in the engine compartment close to the A/C decal. Check for hose leaks and porous or worn tubing. Pressure or temperature control differential too This will enhance the luminescence of the dye, which will make the smaller leaks more apparent. a refrigerant distributor. Gauge readings may not always indicate the same pressure throughout the entire high side or low side of the system.
There are also a few techniques that will help confirm your suspicions regarding those pressure gauge readings. Expansion valve power element has failed or lost
If the cabin air temp is controlled by an air temp/blend door, check actuator operation to see if it moves as you change the temperature setting. If the container pressure is not checked, air will transfer into the system. NOTE: Too much dye can affect the viscosity of the refrigerant oil. document.getElementById( "ak_js" ).setAttribute( "value", ( new Date() ).getTime() ); Enter your email to receive an instant discount. Attach to the hoses and gauge set to the high and low side ports of your AC system. Consider all the factors, including ambient temperature, condenser airflow, engine rpm and humidity, which all affect the manifold gauge readings. This creates the possibility of flooding on start
To find a leak with an electronic leak detector: 1. Symptom: Low cooling Pressure readings: Low side is low. Usually the bottom rows Shine an ultraviolet lamp on the A/C system and look for traces of dye, indicating leaks. Check amp draw verses suction pressure verses condensing temperature Flooded head pressure control: Power head has lost Copyright 2022 Buy Auto Parts. the header. The dye must circulate through the entire system before it will reach the source of the leak. Start winding staying in the circuit too long. While small leaks of a few ounces of refrigerant per year are difficult to detect, larger leaks of about a pound per year can easily be isolated. Yeah, its just like a furnace filter. Check the front of the AC condenser (its in front of the radiator) to make sure the fins arent clogged. discharge valve leaks. Insufficient refrigerant charge, usually accompanied Incorrect starting relay. controls are set incorrectly.
Un-insulated receiver exposed to low ambient. If the gauge reading is normal when first turned on and stays normal for a few minutes, you get cold air and THEN low side goes low, thats a sign of moisture in the system. That saves a lot of time because you dont have to refer back to the component locator or circuit locations. Check the performance variable speed motor or a flooded head pressure control system.
This is called superheat and in an orifice tube system, the superheated refrigerant is what causes evaporator icing. small.
Some of the more common types available today are identified by the following classifications: Each type has advantages and disadvantages, which is why it is so important to follow the manufacturers operating instructions. open due to a foreign material lodged in it, or the port is worn. If R-134a has not been identified as 98 percent pure, the vehicles A/C system should not be serviced with dedicated equipment. Turn off the A/C system and the vehicle. If there has been an oil loss for any reason, repair the cause of oil loss and refill according to the Refrigerant Oil Capacities chart in the Service Manual for the vehicle being serviced. port wedged open due to a foreign material lodged in it. with the compressor manufacturer. They are just a guide to aid you in your diagnosis. 125 PSI / 30 PSI = The system is either not charged enough or you have too much oil in the compressor. Fan cycle control: This is normal if this type Depending on the symptoms, there are various reasons your customers heater might not be working. control. Oil, stains or dirt are good indications of a leak. material causing liquid flood back. occurrence when an oversized outdoor weather hood has been installed. The system pressure is high enough to enable compressor clutch engagement. To perform the leak test, the system must be under pressure. Flooded head pressure control: Bypass condenser Synthetic-based PAG oils are used with R-134a systems.
So you have to refer to the factory legends to learn the identification symbols and then refer back to circuit diagrams to find the splice and ground locations. 3. Using a Go/No-Go refrigerant detector for both service situations can only identify system contamination. Always refer to the manufacturers instructions for proper use of the refrigerant analyzer. Defective oil pump or the oil pump inlet screen This may be a situation where the AC is working fine but the heat is on, diminishing the effects of the AC. Worn bearings, cylinder walls and piston rings conditions. For more information on Interpreting AC Pressure Readings, check out our How To page on the subject. unit. The compressor will shut off once the low pressure triggers the low-pressure switch. The moisture travels with the refrigerant. A compressor overheating will break down the wiring connections. Low outside air temperature on an air cooled system. OR, continue driving the vehicle with the blower on HIGH while monitoring airflow from the vents. Look, I know you want to figure out your AC problem yourself without buying any tools, but you can really screw up your cars AC if you overcharge or undercharge the system.
NOTE: All Nissan vehicles are originally built with refrigerant trace dye (usually a pellet placed in the Rec.
Does the start capacitor Because, on an R-134a AC system, 27-psi.
NOTE: Always wear the protective eyeglasses that come with your black light equipment. THEN, the gas absorbs even more heat from the evaporator airflow, causing evaporator temperature to fall below the freezing point of water. 150 PSI / 30 PSI = There is water in the system. Dont skip this part. With the engine OFF for at least 30 minutes, read the low and high-pressure gauges. Flooded head pressure control: Receiver too small is restricted or shut off.
Covers everything; parts and shipping costs. Thats an indication of a bad compressor. Excessive liquid refrigerant returning to the compressor 1. To test for evaporator freezing, turn off the engine and leave the vehicle for a while. WARNING: Ambient temp is the temperature at the vehicle under the hood, NOT THE WEATHER SERVICE. Recovery/recycling equipment that has a manual air purge should be checked every day before the recycled refrigerant is used. Existing low ambient controls out of adjustment if the system pressure returns to normal once youve applied heat to the orifice tube, the cause may be moisture in the system. As you go over the system, using the black light to check for indications of trace dye, do not forget to check the evaporator condensate drain. The electronic leak detector is a portable, electronic gas detector. ceiling. break down of the insulation between the terminals and the compressor Faulty low pressure control, temperature control, If the detected gas contains a hydrocarbon (flammable material), the unit sounds an alarm and displays HC. Poor distribution of refrigerant thru the evaporator If your static pressure readings dont match the temp/pressure chart and are too high (most common) these are the likely causes: The entire AC system is empty due to a major leak. If the center pulley isnt turning, see this post for diagnostics. This will leave refrigerant in the low side However, if the system is low on charge, the evaporator is only partially filled with refrigerant, so half of it will be cold and the other half hot. })(); Oil trapping in the system. to an undersized liquid line or excessive vertical lift. Check the evaporator, piping, and expansion valve to locate the source of the issue. See this post to learn what type of AC system is in your vehicle.
During the black light inspection if signs of trace dye were evident and the leak source was repaired, you would need to clean the area using the appropriate trace dye cleaning solution. The tool may also be required for A/C service centers according to regulations in your area.