Fix air conditioning using the kit in store?

It is possible for -some- oil to be removed during the recovery and evacuation process, it is not unusual to have it happen, it not unusual to not have it happen. It depends on where in the system the service ports are located, whether or not the recovery equipment recovers thru the low side hose, the high side hose or both, how recently the system was operating and how much oil is near the service port when the service is performed.

One would consider -why- the compressor is being replaced. If the compressor mechanically failed then any debris or contamination needs to be removed via either flushing the components that can be flushed or replacement of the components that can't be flushed. Flushing will remove any oil that may be collected in those components and then needs to be accurately measured and replaced into each of those components. While there is a volume specification for the total AC system, there is also a volume specification for each individual component in the system, the oil needs to be distributed amongst those individual components when being replaced.

There are mechanics that just flat don't know any better, there are mechanics who avoid quoting a proper repair because they seem to think that a half-assed repair (price wise) will scare the customer off. That's not to say that if one were doing something like replacing an expansion valve that the entire system needs to be flushed and the oil replaced with new. In those cases, yes, using "old oil" is perfectly acceptable.

Some do replace the vacuum pump oil after each evacuation, some do it on a regular schedule, weekly for example, some never do.

It is virtually impossible to pull a deep vacuum with contaminated vacuum pump oil. On the other hand, if you don't have the proper equipment to measure to a deep vacuum, it a moot point.

On Sun, 21 Jun 2009 04:57:06 GMT, "MasterBlaster" It sucks the system down, removes the 134 and stores it for re-use,

You need to understand what's going on. In the new systems there is VERY little refrigerant and VERY little oil. There will quite often be some "misty" oil that comes out with the gas, just like when you push the shrader valve on a port you will get some oil spray. But on an old system you are getting nowhere near all the oil in the system. In the new systems that have very little oil to start with the percentage is higher but it's still not nearly all the oil. You need to download and read the manual for the Robinair. The "automatic oil drain" is just an oil separator to measure the incidental oil, IF ANY, that comes out. By measuring it you can then inject replacement oil during the recharge. Read teh IMPORTANT NOTE on page 12 of the manual. As the note says, you may not get ANY oil out. This system does NOT act as an oil removal system, it just is very good at measuring whatever incidental oil comes out so the right amount can be put back in. One reason oil volume is critical in the new systems is because there is so little refrigerant in them that even an extra ounce of oil will have significant negative impact on cooling ability since it takes up space that would otherwise be freon. I'd much rather have and work on an old system with a nice big accumulator in it that holds 10 ounces of "extra" freon.

It's what Usenet specializes in !!

Is that good or bad?? Sometimes it helps to have an excuse....

No excuse really needed, Ash ;>)

It would seem obvious that you shouldn't reuse oil that has been in service for a while. That we are even discussing this implies to me that it is difficult to remove the oil from a system and that in many cases, old oil is reused. Is this a correct assumption? Why wouldn't one automatically do this whenever the system is emptied and serviced? Is this oil expensive or does one use large quantities of the stuff? Thanks.

Believe it or not, I tend to have this effect on people. Don't ask me why... :-)

********* Now you're cooking. It is not cheap and easy to flush out, so this is only done if it is needed or indicated. The oil is not particularly expensive, and you do not require much....measured in some ounces, not quarts or gallons.

By the time air conditioning systems fail on a lot of cars, the car is aging anyway. Refrigerant leaks are the most normal mode of failure, I guess. When the leaks get so bad that it will not hold a charge over the summer season, a lot of people dump the car, or even run without AC.

We have a dammitohell GMC Sonoma that ate a compressor last year with less than 30,000 miles on it. BUT, it is a 2001 model. Compressor is called a V7, a 7 valve GM design, originally designed to try to get more out of a system than there is really room for. Costs about $600 to get it going again. I probably WONT even muck with it, but if I did, I would certainly flush the system, do it right. REASON: The old compressor failed mechanically...Oil could be full of particles, etc. No sense in risking an expensive compressor by doing things half way.