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Preventing Major
Automobile Air Conditioner Failure
By Tom Massey, Owner, Auto Air & More and T & A Service
and Supply
Since the air conditioner is probably the second most
expensive part of the automobile, next to the engine, you should
know what causes air conditioners to fail.
The most common cause of failure is contamination of the system
and leaks. All air conditioners have an accumulator or receiver-dryer
that holds a chemical desiccant that absorbs moisture. Air and moisture
goes to the hoses, especially nylon hoses, and enters the system
even though there is pressure in the system. Filter-dryers are designed
to hold enough desiccant to absorb the moisture that will enter
a system in one to three years time. Of course in the real world,
variations in climate and conditions may cause them to become saturated
in a few months or as long as a few years. However, if the system
is opened for any reason, leaks or accidents, it may be saturated
in minutes. The important thing is at some point the dryer becomes
saturated and will no longer absorb the moisture. At this time,
the desiccant will start to come apart and powder. Also, the moisture
will react with refrigerant (Dichlorodifluoromethane) to form Hydrochloric
and Hydrofluoric Acids. These acids eat away at the metal and aluminum
and also react with the oil and hoses in the system. As bits of
material start to flake off they collect at the accumulator, dryer,
expansion valve, orifice tube, and compressor, as well as the bottom
of the condenser. This can slow or block the flow of oil back to
the compressor and cause compressor failure.
A typical air conditioner only has seven to thirteen ounces of
oil in the system. This oil mixes with and depends on the flow of
refrigerant to circulate to the system. When a leak occurs, oil
is lost along with the refrigerant. Oil traces usually can be seen
at the point of leakage. Too little oil in the system will surely
result in compressor failure. Too much oil in the system will cause
loss of cooling and could result in broken valves in the compressor.
When your system becomes low on refrigerant it is IMPERATIVE that
the location of the leakage be determined and repaired. Since the
oil is distributed to every part of the system, many times the only
way to know just how much oil is left in the system after a major
leak has occurred is to flush the system completely, taking all
of the oil out so the proper amount of oil can be added back to
the system. Converting a system to new alternative environmentally
safe refrigerants also requires removal of old oil.
Certainly, if a compressor fails, the system must be flushed to
remove the contaminated oil and metal particles before a new compressor
is installed. No one would ever allow a new engine to be replaced
in their car without installing a new oil filter and oil. Still
for some reason people often purchase and install a new A/C compressor
without flushing the system or replacing the filter-dryer or accumulator.
When this happens a repeat failure usually will occur or the acids
will build up and destroy the system.
To get the maximum performance and service out of your air conditioner,
follow these basic rules:
- If the system fails to cool, turn it off and have it checked.
Don't continue to run a system that is not working right. You
may cause additional damage to it.
- Make sure you have good air flow through the condenser and radiator.
Make sure the electric cooling fan runs when the air conditioner
is on. This is very important to keep pressures down. No air flow
for as little as 30 seconds can cause pressures to be as much
as 200 pounds too high.
- Air conditioners on today's cars run in the winter as well as
the summer to dehumidify the air. If your A/C quits in the fall
don't leave it open to the air and moisture all winter. Have it
serviced right away. Have the system checked at least twice a
year to make sure you don't have leaks allowing the oil to be
lost from the system.
- Most importantly, if you are involved in an accident or have
to service the system, make sure the filter-dryer accumulator
is replaced to stop acids from forming in the system.
- Don't chance air conditioner service to just anyone who owns
a set of gauges. Make sure your service people fully understand
proper A/C service procedures.
We are equipped to fully service or install a complete air conditioner
system as well as convert your present system to alternative refrigerant
using EPA approved equipment. We can make up or repair most A/C
hoses. Often it is more economical to use new or rebuilt parts versus
used parts. Stop by T & A Service & Supply or Auto Air and
More for an inspection of your A/C system. We feel it is important
for our customers to understand that cars have changed, federal
regulations have changed and service procedures must also change
to meet the demands of today's vehicles. We are committed to the
betterment of the service industry and support the code of ethics
of the MACS (Mobil Air Conditioning Society) and the IMACA (International
Mobile Air Conditioning Association).
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