What to do with uncharged A/C Compressor

[Bob Lanham]

The 69 I recently purchased had the A/C compressor mounted (incorrectly), but not charged with freon. The fan belt was on the compressor. I took the belt off last week after I found out it had cut half way through one of the A/C lines. My question is will it hurt to just leave the compressor on the car uncharged? My understanding is it had been off the car for several years. I didn't want to take the hoses and stuff off in hopes that I might get to making it functional in the near future (sometime before the next millennium).

[Christopher R.]

Re: What to do with uncharged A/C Compressor

If I understand your question, it does not matter what you. There is no difference between the compressor uncharged attached to the engine and the compressor sitting on a shelf somewhere. Once you open them to the atmosphere, the seals can dry out. A rebuilt compressor will be delivered charged with nitrogen and sealed. Although I have had luck in getting compressors working after they have been discharged. Especially if you refill with the correct oil.

Are you trying to decide where to store the compressor? On the car or off? Should not make any difference. Even if you put the belt back on, the compressor should not engage. The activation of the compressor is controlled by its clutch. The low pressure cut off switch should prevent the clutch from activating. So if the thing is just going to sit, it can sit on a shelf or on the car. Just to save the bearings, I would leave the belt off.

[Jerry Clark]

Re: What to do with uncharged A/C Compressor

Hi Bob:

Shouldn't hurt a thing as the system will not activate without freon pressure, it should just freewheel, I would make certain that the compressor and whole system were sealed from as much moisture as possible by keeping all the hoses and connectors attached in an effete to limit corrosion, although that compressor will probably need rebuilding anyway.

Jerry

[Juliet P.]

Re: What to do with uncharged A/C Compressor

I would recommend removing the AC belt and disconnecting the power from the AC compressor. I recently bought a '70. I knew the AC didn't work. I figured next summer I'd deal with it & get the system running. I didn't remove the belt or disconnect the wires. 4 weeks into ownership (in cold Maryland) on one of my several turning the thumb dial past the AC setting (momentarily engaging AC system) to go from OFF to HEAT I seized the compressor & broke the clutch on the front. What a racket and rubber everywhere. I cut the belt roadside & went home.

I believe what happened was that the seals had dried out in the compressor due to no coolant. There is also some lubricant which wasn't checked in who knows how long, and silly me didn't know enought at the time to check & disconnect the AC system. I have a new clutch & spare AC compressor from a friend which will be parts donors when I make my attempt restoring the system. Also note that the compressor runs when you have defrost on (for the dryer loop).

Learn from my mistake and save yourself some potential further system damage and eliminate the possibility of it being engaged. ~Juliet


Juliet's 1970 Corvette

[Jack H.]

Re: What to do with uncharged A/C Compressor

Chris, I think you'll find the low pressure switch came into being on '72 MY Corvettes. Until then, if the control electronics said 'go' the clutch engaged and away she went (or tried).

[Jerry Clark]

Re: What to do with uncharged A/C Compressor

Jack:

Are you certain about the introduction date of 72 for the low pressure switch, just looking for confirmation here, I was under a different assumption.

jerry

[Jack H.]

Re: What to do with uncharged A/C Compressor

No, not certain. That's why I said "I think". Without books here, I can't respond fast/accurate. Early '71 cars continued with the compressor setup from earlier years -- it has no pressure switch to defeat clutch activation.

In mid-71 (think the AIM shows Nov/Dec era), the A-6 shows a change in P/N. NOBODY makes reproduction labels for the late compressor and I'm not sure if they were even used (could be there was sufficient on-hand supply of the early unit to keep the line going without phase-in).

Then, and here's where the 'memory' effect comes in, '72 AIM shows a completely different AC-Delco compressor number that's VERY different from earlier numbering schemes. Joe Lucia can give us the real skinny. And, I 'think' the number change introduced the pressure switch on the back of the A-6 that fed the clutch engage electrical lead (if pressure is low, open circuit and prevent the compressor from turning on regardless of what the electrical controls try to do)....

[Jerry Clark]

Re: What to do with uncharged A/C Compressor

Thanks Jack, that's close enough for me.

jerry