AC Compressor


#1

AC went out on 2003 Honda Accord with 120k miles. Mechanic checked and found bad compressor. Do they usually go bad after 8 years or that mileage? (I live in humid hot South, so AC gets used a lot.) Putting in a used compressor costs $470 with labor, 6 month guarantee, versus new compressor for $700 with labor, 12 month guarantee. Since it’s the start of summer, a 12 month guarantee doesn’t help much more. But will used compressor last for another 5-8 years or 100k miles? When new (or originally in the car) how long do they usually last?


#2

A compressor lasts as long as it lasts. There is no standard mileage or age at which they wear out.

I had to replace a compressor last year on my '96 Subaru. It had about 135K miles on it at the time.

The prices I was quoted had a new compressor for about $100 more than a rebuilt unit. I chose the new one.

If the compressor failed internally, there may be other parts of the AC system that will have to be replaced.


#3

Compressor failure is also something that is frequently misdiagnosed so keep that in mind. Compressor problems may be one or more of the following:
Noisy clutch bearing.'
Worn/slipping compressor clutch.
Leaking compressor.
Noisy compressor itself.
Pressures not correct due to valve problems in the compressor.

The noise problems are usually something that comes on gradually so there is advance notice of a looming failure.

Without knowing what the symptoms are, how this was diagnosed, etc. it’s impossible to say whether your vehicle needs a compressor or not.
When a compressor does fail it’s generally due to the loss of refrigerant oil over the years. With age, automotive A/C systems leak a little refrigerant and with this refrig. loss some oil is also being lost.

This is made worse with modern cars because most compressors are mounted down low and many leaks are around the compressor shaft seal, etc. When the A/C is off oil will pool down low of course and the constant pressure in the system can continually force oil out whether the A/C is being used or not.


#4

The unit on our 1976 Granada lasted 10 years, about 90,000 miles. On my 1984 Impala, it started acting up at 11 years and 200,000 miles. On my 1988 Caprice, it performed well till I sold the car in 2007.

I also was given a 2 year old company car once, a Sable, and the compressor was on its last legs.

Over-tightening the drive belt can wreck the bearing, and low refrigerant level can also end its life prematurely.