1966 a/c compressor without using a thermostat

[Harry L.]

For the past 20 years. I have been running my a/c system using a thermostat causing my compressor to recycle avoiding a freeze up. I just talked to DOM who had rebuilted my compressor 2 years ago. DOM told me that I should never use a recycling system with an A6 compressor. My question to those who run a/c system without the compressor recycling, do you have any problems with freeze up, or does the stv valve, expansion valve and evaporator keep the system in check? Dutch

[Don H.]

Re: 1966 a/c compressor without using a thermostat

Harry, I have had my current '65 with AC for almost 20 years & had a '64 AC for 14 years. Both used the stock AC system for many miles and never had a freeze up. Don H.

[Mark E.]

Re: 1966 a/c compressor without using a thermostat

I've had these systems freeze up a few times. It's a symptom of a problem. IIRC, in my separate cases over the years, it was a plugged evaporator, bad expansion valve, system over charged.

Maybe an AC expert will chime in. Some of the CSMs have a good AC diagnostic section which you might check.

[Robert B.]

Re: 1966 a/c compressor without using a thermostat

Harry, I have never had a freeze up problem with either my '66 or '67 factory A/C system. Both are running R12 - the '66 has an STV, the '67 uses a POA valve. These valves are designed to bypass refrigerant around the evaporator when certain temps are reached to avoid freezing the evaporator coil. I've driven the '67 over 40,000 miles over the last several years, much of that using the A/C system. Never had a freezing issue.

By the way, Dom is the best on these compressors!!

Bob

[Harry S.]

Re: 1966 a/c compressor without using a thermostat

Harry, as long as the expansion valve is not jammed open and working properly and the STV is working properly you should not have a freee-up problem.

[Domenic T.]

Re: 1966 a/c compressor without using a thermostat

I would like to back up to the reason I think the A6 should never have the cycle switch.
The A6 is a tough compressor but the weakest part is the clutch hub. The main shaft diameter is reduced to 1/2" where the clutch hub mounts to it, this is the 2nd reduction of the main shaft diameter. The clutch is metal to metal and the clutch hub is not precision built. My guess is that the clutch hub was hand laid in a jig and riveted. None spin true and that's why the spacing between the clutch hub and pulley is between .022 and .057. To cycle this clutch unit (clutch hub & pulley) at driving speeds will effect the life of the clutch and compressor. When the magnet pulls the hub to the pulley, they slip to give the inner parts of the compressor time to gain RPM's. When the slipping happens at a high RPM the hub can go off center and tweek the main shaft until it's release. This also creates a balance problem and is very hard on the pulley bearing,clutch hub rubber, and not to mention that the ceramic seal is directly behind the clutch.
When I get the compressors in the clutch area of the pulleys all need to be machined because of normal use. That's why I suggest turning the AC on at a low RPM, that will keep the compressor and clutch happy. During a charge I have seen sparks fly when the clutch is operated at a high RPM.
The manual actually has a clutch break in procedure if you can believe that! Not necessary.

Dom

[Larry M.]

Re: 1966 a/c compressor without using a thermostat

Agree with Dom...........

That being said, many A6 compressors have been converted to on/off cycle and still seem to perform. Not certain about their lifespan. They were not designed for this service as Dom states, and you should try and keep them operating per their original concept.

FWIW.

Larry

[Harry L.]

Re: 1966 a/c compressor without using a thermostat

Thanks for the good participation to my thread, I will now run my compressor the way it came from the factory. Dutch

[Harry L.]

Re: 1966 a/c compressor without using a thermostat

Well, I disassembled the recycling system from the compressor today and took my 50yr. old a/c for a ride. To my surprise my a/c never performed as good as today. That air coming out of the vent was a constant 43degress with no freeze up. I can't believe that I had not done this before. Thanks to DOM who initially guided me in the right direction and all of you who chimed in with your knowledge. Dutch

[Domenic T.]

Re: 1966 a/c compressor without using a thermostat

Dutch,
That makes me so happy. I know I'm a little anal about how to treat something over 50 years old, but we can't get parts for these beauties as easily as when they were new. All this stuff was not tested for 50 years and now we know what it takes to keep em running. I'll be there to help if a problem was caused by the cycling. Thanks for the update.

Dom