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Troubleshooting Solution For Automotive Air Conditioning Systems



Here are some easy steps to help you troubleshoot your car air conditioning system. Freon leaking from a defective o-ring, gasket, hose or component.Expansion line or refrigerant charge line clogged.Defective compressor or compressor clutch.Defective fan motor or fan motor resistor.Condenser or evaporator damaged or defective.Emptiness flows.More Articles …




The most likely cause of a problem with the cooling of the car’s air conditioner is a lack of refrigerant in the system. If refrigerant has leaked through a leaking compressor or O-ring, leaked through a perforated plate in an evaporator or condenser, or leaked through a leaking pipe, the leak must be identified and repaired before the system is started.

In many systems, the compressor will not turn on when the refrigerant level is low because the “low pressure safety switch” prevents the compressor clutch from closing when the system pressure is low. This protects the compressor against possible damage due to lack of lubrication.

Therefore, first of all, it is necessary to check the inclusion of the compressor. If the magnetic clutch of the compressor does not engage when the air conditioner is on, the problem may be a fuse or a blown wiring. If a fuse is blown, replacing it may temporarily restore cooling. However, the root cause of the blown fuse should be identified and eliminated Body to prevent it from happening again.

If voltage is applied to the magnetic clutch, but the compressor does not turn on, the clutch is faulty and must be replaced. If there is leakage around the compressor shaft seal, the seal must also be replaced.

If the clutch works, but the compressor does not rotate (the belt may protest!), then the compressor is seized and needs to be replaced.

Problems With Cooling Variable Capacity Compressors

In some newer car models, the air conditioner compressor does not have a clutch for turning it on and off. The compressor runs the entire time the engine is running and uses a variable displacement to increase or decrease the amount of refrigerant it pumps through the system.

In this type of configuration, the air conditioning module or PCM monitors the temperature inside the vehicle and changes the compressor displacement as needed to increase or decrease cooling. Inside the variable displacement compressor is a swash plate that changesThis is the stroke of the pistons as they move forward and backward. Increasing the stroke increases the amount of refrigerant pumped into the system to provide more cooling. Decreasing the stroke reduces the amount of refrigerant pumped through the system to reduce cooling.

If there is a malfunction in the control system that prevents the compressor from increasing the displacement when more cooling is required, the cooling capacity may be insufficient for the driver and / or passengers. Such problems can include one or more faulty internal temperature sensors, a defective compressor control module or wiring between the module and the compressor, or a swashplate problem in the compressor.

A scanner capable of reading climate data can be used to test the operation of the temperature sensors of the indoor air conditioner. If the displayed temperature does not match the actual vehicle temperature, the temperature sensor is defective.

If the temperature sensors show correct values, the scan tool willit can also be used to verify that the A / C compressor is receiving the correct commands to change the displacement when the temperature rises or falls. Failure to command to change the offset will indicate a faulty control module or a problem in the wiring between the module and the compressor. If the compressor receives commands but does not change the offset, the problem is with the defective compressor.

A / C Compressor Error

Compressor malfunctions are usually the result of loss of lubricant, which in turn occurs due to low refrigerant levels in the system, blockages (for example, a clogged diaphragm that prevents refrigerant and oil from entering the compressor), and no lubricant leaks or improper maintenance procedures (do not add oil to the system to compensate for oil loss due to leakage or replacement of components) or the use of improper lubricant.

Older systems with R-12 (up to 1996) require mineral oil, and systems with R-134a (1996 and newer) require different types of PAG oil or POE oil. Many 2015 and newer vehicles also require a PAG oil of their own type for R-1234yf air conditioning systems. Using the wrong lubricant in the air conditioner can damage the compressor. Always follow the vehicle or lubricant manufacturer’s recommendations for compressor oil.

Pressure Testing

The next thing to check when troubleshooting non-cooling problems is system pressure. To do this, you need a set of A / C service indicators. Attach the service indicators to the high and low pressure valves. If the high and low pressure gauges are low, the system is low on refrigerant and the system needs to be charged. However, before adding refrigerant, check for refrigerant leaks.

Air conditioner pressure measurement circuit

Refrigerant Leaks

In all vehicles, refrigerant flows through joints and through microscopic pores in pipes. The older the car, the higher the penetration rate.Newer vehicles have better seals and barrier hoses, so refrigerant leaks are typically less than a few tenths of an ounce per year. However, the system capacity is usually less even in the latest generation vehicles, so the loss of refrigerant has a very negative effect on cooling efficiency.

Various methods can be used to check for leaks. Control oil stains and damp spots indicating leaks in older R-12 systems are less noticeable with newer R-134a and R-12234yf systems because carbon polyamide lubricants are not as “oily” as mineral oil. This makes it difficult to find leaks.

Leaks can be detected by adding a special dye to the system (available in pressurized cans pre-mixed with refrigerant), an electronic leak detector, or simply old soapy water (spray hose fittings and bubble control). If your air conditioner has little or no refrigerant, you need to first add refrigerant to the system before you can find a leak. Top up withSystem a can of coolant while the engine is idling. If you add dye-containing refrigerant, a small leak may take several days. Larger leaks, such as a broken pipe or fitting, a leaky compressor shaft seal, or a leak in the condenser, should occur faster. An electronic leak detector can detect leaks as soon as they occur.

Air conditioner refrigerant leaking

The most difficult to detect leaks originate in the very heart of the evaporator. The evaporator is buried deep in the HVAC box under the dash, so you can’t see it directly. One of the telltale signs of a possible evaporator leak is oil mist or fog inside the windshield through the defroster ducts. It is best to use an electronic leak detector to check the tightness of the evaporator core. Insert the probe tip into the cooling outlet and turn on the air conditioner. If the detector beeps or blinks, you have found a leak.

Prand a leak is found, it must be repaired before the system is fully charged. In most cases, repairing leaks involves replacing o-rings, gaskets, or hoses. However, if the evaporator or condenser is leaking, repairs can be costly. Replacing a leaking evaporator core usually involves a ruptured dashboard and removal of the HVAC box. Depending on the application, this can take anywhere from 8 to 12 hours!

One repair option you might want to consider if your evaporator, condenser, pipe or pipe is leaking is to add a refrigerant container containing sealant to your air conditioning system. If the leak is small, the seal can often save you the cost and labor of replacing an expensive part. However, the use of a sealant comes with a certain risk as it can cause blockages elsewhere in the system or cause the compressor seals to swell too much. Most professional technicians do NOT recommend using air conditioner sealants, however many No people have used these products successfully and have not faced any problems. You have a choice.


To diagnose an air conditioner refrigeration problem, it is best to attach a pressure gauge to the system’s high and low pressure service set. Although poor cooling is often the result of a low refrigerant charge, many other factors can also be the cause (see table above).

automomotive air conditioning troubleshooting

How to know if your air conditioning system needs refrigerant: check the low pressure gauge with the engine stopped. On a day with a temperature of 80 degrees, the LOW indicator should read at least 56 psi. Inch if there is enough refrigerant charge in the air conditioner. On a 90 degree day, the LOW side should be about 70 psi or more. If the LOW value is lower, the air conditioner will probably require additional refrigerant. Real r



Why is my air conditioning not working in my car?

A faulty rotary knob can also affect your ability to turn on the automatic air conditioner, as well as a faulty switch, stuck valve, faulty wiring, blown fuse, or clogged air ducts. Many car owners make the mistake of not using an air conditioner during the cold winter months.

What are the symptoms of a bad auto AC compressor?

AC compressor breakdown or breakage symptomsThe temperature in the cabin is above normal. One of the first signs of compressor problems is that the air conditioner is not blowing as cold as it used to. …Loud noise when the compressor is running. …The compressor clutch does not move.January 6, 2016

How do I fix my car air conditioner that is not cooling?

The most common causes of malfunctioning air conditioning systems are leaks or compressor problems. If your air is blowing cold but not cold, the problem could be a clogged filter, a malfunctioning fan, a malfunctioning radiator, or simply needing to recharge the air conditioner.