[KDirk]

Had my compressor clutch seize this past week. Not too bad considering it was the original Harrison/GM 18 year old compressor. This has left me with a bit of a dilemma.

I have a new compressor and accumulator, as well as an expansion orifice tube and all needed o-rings. I am going to convert the system to r-134a for ease of future servicing.

Per the 91 FSM, I have added 2 oz of new esther oil to the compressor and 5 oz of new esther oil to the accumulator. I was not able to recover any oil from the old compressor or accumulator, it must have blown off when the compressor failed.

Now here is my problem. I know mineral oil (r-12 systems) does not play nice with 134a (which uses PAG oil), and esther oil mixes with either mineral oil or PAG oil so can be used with both refrigerants. I have asked the dealer I go to for service that is beyond my ability to flush and recharge, but they are indicating that a flush shouldn't be needed.

If I have them evacuate and charge without flushing, what risk do I have of premature failure due to residual mineral oil left in the evaporator and condenser? I have no way of knowing how much, if any, is left there and I question the wisdom of not doing a flush.

Am I right, or do I listen to the dealer who tells me "we do that all the time" (meaning conversion with no flush)?

Replies from those with knowledge of refrigeration systems will be greatly appreciated.

KDirk

[padgett]

I'd flush but have a friend who is more than capable.

[harry yarnell]

Check the old orifice tube for debris. None found, button the system up with your new components and PAG oil.
Debris found; flush and pray you get it clean.
This is the way I've done it for 45 years.

[spamseptictank]

Always flush the system when converting from R12 to R134a. The two refrigerants are corrosive when combined.

[harry yarnell]

Flushings not necessary when converting to 134.

[Bobby Valines]

Isn't there a oil used for 134a that mixes with the r12 oil ? Or is that what esther oil is? I have done heating and cooling installs for 20 years in houses. We never flushed the system but we did vacuum it before and after replacing the compressor and we put on a dryer ( filter ). The new accumulator should help. If it was me and spent all that money on a compressor I would try and get it flushed.

[harry yarnell]

Mineral oil used with R12 isn't compatible with the replacement 134 Freon, so you use a PAG or ester oil designed for 134. The oil in a modern A/C system floats around with the freon like the oil in a 2 cycle engine. I've never seen oil pool in the compressor; maybe the accumulator.The old boat anchor A-6 GM compressors from the 60-70's had sumps where the oil could accumulate, but not the newer DA(HR6) units used on the Reatta. So when you replace a compressor, you should ALWAYS replace the accumulator. I put 4oz. of oil in the compressor, and 4oz. in the accumulator.
ALWAYS replace the two special sealing washers on the compressor manifold. As for the line O rings, I'll use the green (blue)ones on any lines I disconnect. The others I leave alone.

Oh, ALWAYS use a new compressor. Any 'issues' I've had, have been with remans.
I've used ackits.com and E-bay for purchases of compressors.

[NEMO]

Flushing the system is the best way to clean all the lines. It can give you the chance to replace the O rings with the Nitrel ones{ if my spelling is right}I was told that these are what are used in the , r134 system.When I did mine this is what I did.works great.COLD AIR out of the vents.

[Richard D]

You have already spent many $$$ for parts, I would think that flushing would be a small cost compared to the total cost. Even though some members say it is not needed and may not be for me the peace of mind knowing that all those new parts are operating in a clean system is reason enough. My .02 worth.

[KDirk]

Many thanks for the input. It seems the consensus was what I already wanted to do - flush it!

A few other notes:

I bought a NEW compressor. I will never buy any reman'd garbage unless there is no other option. I've seen too many premature failures of reman parts to even consider them. The new compressor came with the proper seals for the suction/discharge block

I used esther oil (listed as a dual-use r-12/r-134a compatible oil) in both the new compressor and accumulator. PAG oil is for 134a only, and mineral oil is for r-12 only, esther will work with either. I did this initially because I though I was going to put R-12 back in the system. After more consideration, I decided against that since it would be wasting almost 3 pounds of the 20 or so of r-12 I still have left and may need for other reasons.

I followed the FSM guidelines for how much oil to place in the compressor and accumulator, and I have a new expansion orifice tube to install. Also have new O-rings for all fittings disassembled thus far, and a new low side pressure sensor and O-ring to install as well.

I guess I was a bit surprised when the dealer told me they didn't normally do a flush on a conversion, for the peace of mind it seems stupid not to. Apparent cross contamination of a converted A/C system has left many people I know with much more expensive repairs that shouldn't have ever been needed.

So, I will tell them I want a flush before conversion, even if their professional opinion says otherwise.

KDirk