A/C question

[mikeringland]

When I purchased my '72 last year, the previous owner told me that the A/C had been working, but the clutch seized and he simply took the belt off. I finally got around to looking at it. The car was converted to R-134A in March of '99. I decided to just buy a new 4 Seasons Everco Compressor/Clutch and replace the old unit entirely. I swapped out the unit and went to recharge the system. There was very little pressure on the system before I removed anything, so I figured there is a leak somewhere. I bought one of those self recharging kits from Autozone and it states that the system should be recharged to 40 psi. I attempted to recharge the system and could only get it to about 30 psi. It simply will not take any more, but seems to hold steady at 27-30 psi. Of course it's 45 degrees out here today, so I also can't really tell if it's truly blowing as cold as it should be. I have 12.5 volts going to the compressor. I also cannot really tell if the clutch is engaging when the A/C is turned on.

 

My question is, does anyone know what the psi level should be for this car? Is it 40 like the recharge can says, or is it 30? I wasn't sure if maybe older cars had a lower psi value than newer ones. I'm going to get around to looking for the leak. I didn't want to just take it to some shop and spend endless amounts of cash for air conditioning. 

 

Thanks, 

 

Mike 

[Leghome]

My 72 was recharged with 134A and we only put in 2/75 lbs of 134. Do not know anything about PSI on our AC systems

[overdrive]

Any time you open up the system, it must be evacuated of any moisture that gets in while open. That requires a vacuum pump running for a good while. Did you put a vacuum on the system? If not, it won't work very well.

 

Dan

[Sam (Bones)]

ALSO...the pressure needs to be checked with the AC running, if you watch the front of the compressor, you should see the outer hub of the clutch spinning, at 45 degrees the system may not come on but if you use defrost, the clutch should kick on

[Mo's70MCs]

I agree with Dan, anytime you crack it open the need for evacuation is so very important. Yet I'm speaking from an R12 perspective, the worse enemy is moisture in the system. A simple wrong manifold and hose hook up can easily introduce moisture if not purged correctly, although eventually the dryer will slowly correct it, it is important to follow certain procedures​ that can not​ be overlooked. One of those often overlooked and hardly discussed is system flushing. The worse enemy is contamination, black death is one that was discovered years ago, once there is black death in the system, it's recommended to replace everything in the entire system since flushing might not remove everything ... I was actually leary at first to start servicing my own systems, yet with the rise in price of freon and the regulation. So I had no choice but to inform and educate myself if I didn't want to pay the exorbitant pricing. There's a firm belief in me that some things should be left and done by the pros, in fear of screwing something up. The lack of knowledge didn't actually dictate my need, more like the pricing.

[mikeringland]

Well it was a lot warmer today, so I tried using it and it appears to be working. I did not vacuum the system, I'll just wait till next time it breaks to do that I guess, haha.