Last year the AC system needed a boost. Hooked up the gages, purged the line air and followed the manual specs with adding freon. Basically checked the temp and running 1500 RPM added about a 1/2 lb to bring the high side up to about 210 PSI.

Down again this year. The 1 Lb can was still hooked to the fill line and had about 1/2 Lb remaining. Once again it took about 1/2 Lb to reach presure - about 225 PSI at 107° F.

Revving to 4000 RPM the high side will creep up to about 300 PSI. Thats sitting still so the condensor isn't getting lots of air.

At 1500 RPM high side was 225 PSI and low side was 35 PSI. At 2500 RPM high side is 260 PSI and low side drops to 15.

Does this sound right or is the system overfilled?

Also there are no visible signs of AC oil anywhere - joints, compressor seal etc. The caps over the schrader valves for the high & low taps were under pressure so I'm suspicious thats where the leaks are.

 

I certainly would not add more. Are you sure ambient temperature was 107 degrees? High side seems right at idle. I'm a little concerned about your 300 psi at 4,000 rpm. Are both of your fans running? You should not have pressure under the caps, you can tighten the schreader valves with a tool to stop them from leaking.

 

Outside ambient was 100.4°, the car was in the garage and the T-Couple on the workbench was reading 107°.

Interesting you mentioned both fans. The secondary fan comes on when the water temp is high enough but not automatically when the AC is on. Is it supposed to?

I was pretty concerned about the 300 PSI as well, but again that at standstill, I would suspect it won't run that high of pressure with plenty of air running through the condenser at speed. Which raises the question about the secondary fan - if it's supposed to be always on with the AC...

The high pressure switch is something in the high 300's FWIW, per the manual.

I may just purge the system pull a vacuum and refill it with the spec mass of freon to be sure.

The schraders are tight, I have a key for them. If I do refill the system I'll buy a couple new ones from the Mazda dealer or an AC shop.

 

Isnt that too high ?

I think you over do it.

but still, your system shouldn't loose any thing in just a year, you might have a really slow leak. Have you check ?


Speaking of that, I think I should check mine too. need to get some Dual gauges for both my 7 and 8.

 

I'd be happy with your pressures.

 

My leak detector is old and doesn't work anymore. Kind of like me. I tried using a propane torch sniffer but the flame color doesn't go green anywhere I've checked with the suction tube. Not certain that method works with R134, but it should.

I'll purge and refill this weekend then measure the pressures again.

 

^1 propane method does not work for r134 and 2 if you do that on a R12 system (which is where it works) and you breathe in the Phosgene gas(produced from burning R12) you could die or at least get damn sick. Get a black light if you have dye in your system and check it...if not get some dye and run it through the system for a week or 2 and then check with a black light....the pressures are ok...300 seems a little high but you def want to find that leak..

 

Thanks for the responses.
Yeah I'm aware of the Phosgene by-product, but back when I first learned to find AC leaks we didn't have electronic detectors. Heck I made it this far. That was in Raleigh BTW.

Not real fond of the dye tests, the dyes sometimes tend to cause other problems 2-3 years (read after repair warrantee expires) down the road.