Folks,

I'm posting this in the diesel section because we seem to be the hardcore folks keeping their cars running 200-300-400+Kmiles. It is inspiried by the general overheating general topic just posted. So there seem to be a bunch of A/C problems posted recently as well.

My question is should there be some planned A/C maintenance to prevent or delay the replacement of major components? Should there be a planned flush, oil drain, and refill at a certain mileage? Would this prevent compressor failures? Should O-rings be replaced by time or mileage?

Let me know your thoughts. Maybe a collection of experiences by compressor type and area of the country might show some trends. Southern A/c systems need attention at 100K,.. Northern systems need o-rings early, who knows... any suggestions or thoughts? Just run 'em till they drop?

Thanks,
Chuck

AC systems rely on lubrication from operation.... Northerners allow the system to rust and decay internally by only using the system 2 months of the year.

The only way to "service" the automotive a/c system would be to completely disassemble, flush all components, dump oil out of compressor, rinse compressor with fresh oil. Replace all o-rings and filter/drier, evacuate and charge.

The risk of introducing moisture into the system and the risk of a leak due to this process, FAR outweighs any possible gain.

If it is cooling well, and has lost no more than 1 oz. of refrigerant per year, count your lucky stars and be happy.

This is a perfect situation in which to apply the old addage "if it ain't broke, don't fix it."

Good luck,

Larry,

In general I agree if it is working - let it go. It seems there is a typical life expectancy of a compressor even in a good A/C system. In several of my past vehicles, they seem to go out in the 120,000- 170,000 mile range based on my climate and usage patterns. I beleive that the failures were on systems that still had full charges in them, not due to leakage. Obviously the leaks must be fixed for any system viability.

Seeing that many people in this group tend to keep their cars much longer than the typical domestic vehicle, I am wondering if a dis-assemble, flush, add fresh oil, o-rings, a dryer and refrigerant would significantly add any to the lifespan of a compressor? Or do they just wear out? I'm sure they do just as the diesels themselves will eventually. But it would be nice to invest $100 in preventative maintenance at 125,000 miles and get 250-300,000 miles out of one. Anyone have a record lifespan of a compressor?

Thanks again to all for sharing your expertise, the people here have been helpful, friendly and very willing to share their time. It is very appreciated.

Chuck

I've always heard the theory that you should periodically use the air conditioner even when not required, to keep the lubrication distributed. Maybe this helps keep the o-rings moist with lubricant too.

So mine get some activity right up until the bitter cold months when it won't turn on due to the ambient temperature sensor.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Yes, turning the compressor frequently keeps the seal lubricated. As far back as the sixties, Detroit began seeing to this by having a/c mode on the switch between off and heat mode. This way you put the switch momentarily on the a/c mode kicking in the clutch. One turn or even less is all that is necessary to oil the seal.

The original compressor in my 240D went 380,000 miles before replacement. At that point it was engine time and the compressor had been getting noisy, so I replaced it before it scattered.

I still contend that the scope of the job to flush, replace filter-drier, add oil, evacuate and recharge is outweighed by the chance of introducing moisture or a leak in the system. This comment applies to a perfectly proper working a/c system. If the system has leaked out, or needs other attention, then going through it completely could very well be in order.

Again, this is a great place to apply the old "if it ain't broke, don't fix it" axiom.

Good luck,

Well, there is one item which might be helped by replacement before it ' goes south'.
Some Reciever Dryers have a bag which holds the dessicant. When this gives way due to age or vibration it lets this stuff go downstream. This is always a bad deal. If you want to evacuate,replace the R/D , ( adding back the same amount taken out by the old R/D from a newly opened can of oil ) and put in an inline filter to make sure that if the new one gives way in a few years the stuff will be caught before it gets to the Compressor I would not consider this a terrible thing to do. .... ( unlike Larry) lol.
If you can find a R/D which holds the dessicant in a Wire container you will be upgrading the system when you do this job.
Keeping the fins clean on the condensor is important to how long the compressor stays on at any one time... so that should be done often.. and be sure you aux fan is working well... the same applies to its effects on the time the compressor has to be on to keep the inside of the car the same temperature....

I would agree with leathermang about the r/d change except that, out of curosity, I have cut open every filter drier I have ever replaced. The ones from 123 a/c's, at least all of the ones that I have replaced, don't have a dessicant bag, they have a one piece porous "rock." Every one of these rocks have been intact.

If you WERE to decide to replace the r/d as a preventive maintenance measure, I would suggest that you drill a hole in the bottom and see how much if any oil drains out, then add that much to the system before evacuation and recharge. Breaking every connection and replacing o-rings probably introduces much more of a chance of introducing a leak than it does for preventing one.

Best of luck,