Thread: AC problems, relief valve keeps popping

I've got a 91 SE-R, last week the compressor locked up on me. I put a new compressor off a 94 on it, I've got 134a lines on the car. I've still got the original R12 condenser, a new R12 reciever dryer, original R12 evap core and expansion valve. While I was putting on the compressor and reciever dryer I also replaced every o ring in the AC system. Yesterday the pressure relief valve on the compressor output line blew and leaked all my freon. I had a second one laying around from another line. Recharged it today and it blew again. I haven't checked the pressures with the AC running, well I did originally to make sure the compressor was working properly, but I don't remember what they were. I'm guessing that I'm creating way to much pressure in the ac system and that's why it relief valve is blowing. Would an expansion valve not working properly cause it to create way to much pressure and blow? If not what would be causing the over-pressurization? I know my AC system is kind of a Frankenstein, but it worked all last season until the lower line by the compressor got hit by a rock on the freeway and cracked.

Any help is appreciated.

A clogged expansion valve could certainly cause a pressure build up. Might want to have a look at that. So will overcharging the system.

I only put in 1.3lbs today, I figured if anything that was slightly under full. My hood's been replaced so I don't know for sure how much I'm suppose to put in. I've tried searching online but every place I click want's me to open an account and pay them for the info.

Is one of your fans kicking on with the A/C on?
I had a similar problem in an 82 ZX and the condensor fan wasn't turning on with the A/C and would blow after a while. Fixed the fan and it worked after that.

Don't put any more than one can in. Should be between 25-30psi on the low pressure side.

You may be onto something. I don't think I've ever seen that fan kick on. I will check if it's got power and ground tomorrow. If it does I'll use my power probe to see if I can get it to kick on.



I work in a shop and I've been using an AC machine to recharge it, that's why I was wondering how much r134a it's "suppose" to take. On the toyota's I work on it's got how much the ac system takes on the hood of the car, but on mine the hoods been replaced at some time or another so I don't know how much is suppose to go in. I tried using one of those cans last year and for some reason my ac system wouldn't accept the charge so it pretty much forced me to use the shops ac machine.

You can diagnose whether it's a fan problem by driving it on the freeway with AC on. If it still pops, it's not a heat rejection issue.

Pretty sure it's 13oz.

The fan it's self works, I powered it up today at work and it came on. It's getting power but no ground. I don't want to hunt down the broken wire so I'm just going to run a manual switch to the fan and use it whenever I'm using the AC.



I had a chance to check on alldata today and a 94 system, which is bascially what my car now has called for 1.3-1.5lbs of freon. Thanks though

So I will be getting a new pressure relief valve tonight and a switch and rig the switch up tomorrow so hopefully I'll have working AC tomorrow. Thanks for your input everyone

The low side pressure will change based on temp outside. R12 is expensive, but operates at lower temps. You'll want about 45-50psi on R134a if it is 80+*F outside.