What A/C pressures?

[karter74]

Hey guys, I am having some problems with my 92 Navajo's A/C system(still R12). Right now it is blowing hot air and I have recharged it with more R12. My question is does anyone know what pressures the low and high side need to be at (perhaps found in a FSM?). That, and if there is air in the system from a leak, how would I know this and what is the best way to purge the air out? Thanks!

 

[ryf]

they make pumps to purge your AC, consider buying an O-ring kit if the hoses look good, and maybe converting it to 134a (cheaper to refill) I don't have the pressures, but I know you're going to waste a bunch of money on r-12 if you have a split/dried out o-ring and it leaks back out in a week or two. just a thought...

 

[karter74]

i doubt an o-ring split, since it was working fine like 3 weeks ago, i think there is a leak, i had to tighten up a fitting on the compressor and I think maybe some oxygen got in. BTW, i dont ever plan on retrofitting it cause i have about 40lbs of R12 stockpiled from before it was illegal

 

[ProPhotog]

Hey guys, I am having some problems with my 92 Navajo's A/C system(still R12). Right now it is blowing hot air and I have recharged it with more R12. My question is does anyone know what pressures the low and high side need to be at (perhaps found in a FSM?). That, and if there is air in the system from a leak, how would I know this and what is the best way to purge the air out? Thanks!

each truck operates differently on the pressures, and until you evacuate the system completely and draw vaccum on it, it's hard to determine a leak. get some dye and inject it to help find leaks. you'll definitely want to evacuate the system before a recharge.

 

[Glacier991]

I'm thinking if it were me I'd recover what was left, replace the accumulator and evacuate it thoroughly and add a little oil, some dye and the proper refrigerant charge. pressures will depend on day... meaning ambient temps, cabin temps, condensor cooling etc, but low side should draw down to 30 PSI or so and high side can run into the 200's. I will assume your clutch is kickin in and the compresssor is running. Check the UseFul Threads, there is a good AC thread there, the title talks about converrting but it has a lot of AC info and links to a full R-12 recharge.

 

[Texan01]

Generally you should have around 30psi on the low side and 150psi on the high side (with a good fan clutch)

A lot of problems can occur if the fan clutch itself is dead, as it won't pull enough air through the condenser to cool the refrigeriant down to liquid again. or it allows the head pressure to get so high it blows the safety valve and purges excess freon out. (around 350-400psi).

Does it get cool on the highway? if so, problem may lie with the fan, if not, could still be undercharged, or you have a restriction somewhere other than the orifice tube.