1970 Evaporator Removal

[Dan LeBlanc]

So, I'm starting to get in the frame of mind for overhauling the refrigeration side if my climate control system. Part of that is removing and flushing the evaporator.

The method in the shop manual seems pretty invasive. Is there a less invasive way to do this or am I married to dismantling half the car?

The evaporator has been freezing up of late in evenings when it's not very warm out (low 60s).  Is that a POA or expansion valve problem?

Don't shoot me but I'm also thinking Pro6ten compressor and perhaps a POA delete kit with R12. I've read of great successes in other GM forums with this compressor

["Cadillac Kid" Greg Surfas 15364]

Dan,
Working correctly as intended the 70's have got a bullet proof system.  The evaporator freezing up can be anything from just a bit short of gas to a poorly adjusted POA using R-134a to dirt on the evaporator, to a loose expansion valve  thermal bulb.
Greg Surfas

[chrisntam]

I went through my system 2 years ago, I've attached a pic of the evaporator, it was fairly dirty.  The system was not working when I took it apart.  The POA was stuck to the evaporator, I had to cut it off.  I sent it to a place in Florida to be rebuilt, cost was around $200, IIRC.  I got a rebuilt A6, bought a new evap core, replaced the expansion valve & drier (rock auto), flushed the condenser and the hoses, reused the original hoses.

System is working fine, except the front seal is leaking on the compressor, it is spewing (my words) oil.  Word on the street (in talking to people) is to replace the compressor, not just the seal.  We'll see.

I had it all apart with the engine out, it was much easier.  I recall the center housing sits atop the evap core housing and it has to come out first.

Perhaps Minesinger will chime in and confirm.

[Dan LeBlanc]

Your oil seepage sounds normal for an A6 compressor.  The front seal is designed to weep oil to keep it lubricated.  If you're not losing refrigerant, you're good.

Some cars using the A6 compressor had a shield bolted on it to help keep oil from being slung about under the hood.

Still on the fence about the Pro6ten vs. getting the A6 rebuilt.  Price wise, I'm looking at the same $ amount.  Perhaps if I send it to a rebuilder and not get a Chinese remanufactured unit, it may be ok?

[chrisntam]

I've had other A6s (rebuilt), those didn't leak oil like this one does.  Leaks to the point that the distributor cap is covered with grunge and the water pump always has oil on it (puddled).  I think it leaks a very little bit of Freon, I think it needs a can now, it blows fairly cool, but not cold.

[Dan LeBlanc]

Uh oh.  Yup, it's doomed!

Have you gotten the remanufactured units from a parts store in the past or have you sent yours out to be rebuilt?

From what I understand is that they can install a modern neoprene seal now to pretty much alleviate the problem.

["Cadillac Kid" Greg Surfas 15364]

Dan,
First of all there is an upgraded seal, however all shaft seals for compressors depend upon an oil film to seal the ceramic mating surfaces.  That said it is critical that the seals be lubricated from the very FIRST revolution under power.  Not adding oil to the sump through the plug in the compressor and not turning the compressor over by hand to prime the oil pump and thus lubricat the seal is typically what kills the compressors that are declared "DOA".
That said if you do the change out and start up correctly I have had great luck lately with AC Delco rebuilts.
Greg Surfas

[Dan LeBlanc]

Maybe that's what happened to mine . . . the tape was still over the oil plug when I got the car!

["Cadillac Kid" Greg Surfas 15364]

What ever they say in the instructions (with or without oil) I always drain the sump and add 5 ounces of (I typically use Ester) oil and then turn the compressor over 20-30 times with the compressor sitting in the position it will be when installed.  After installation and evacuating/recharging I again turn the compressor over 20-30 times before I actually energize the clutch under power.
Greg Surfas