NJTman

Hi A/C guru's in 1st gen land...


Anyone know what this gizmo on the back of the A/C compressor is, and what would make it intermittently act like a camel, and spew clouds of spit all under the hood ?


I realize that the A/C unit most likely bit the dust, but just wondering if anyone knows what that relief valve is for ? Is it indeed a relief valve ? Why go bad, Tonga ask ?

Uchmos Rassigras !

dodgenstein

That's the high pressure relief valve. If the high pressure side is blocked, the engine fan isn't working correctly, or the condenser gets blocked, it opens to protect components from damage. Adding too much refrigerant will cause excess head pressure also. I had a weak fan clutch that would cause blow off at extended idle.

NJTman

Does it expell refrigerant???? The truck wasn't hot yet. Just started, maybe 2. Minutes running.

NJTman

Apparently this has been questioned before.
https://www.dieseltruckresource.com/...4/#post2990874

I didn't know it was called a pop off valve...my bad.

I'll order up a new fan clutch if mine isn't whirring when it's supposed to.

edwinsmith

It spews oil and refrigerant. The biggest problem is, how much oil was lost? When Mine blew out the first time I completely took the system down and blew out the oil so I could get the proper amount back in. Mine blows at about 600 psi which is quite easy for me to hit.

My system was originally designed to use R-22 but I converted it to R-134a. It doesn't cool as well as it should so I'm considering the propane/butane stuff.

Edwin

Jim Lane

R-22?
If it does not vent,
The compressor would stall and either burn out the clutch or break your serpentine belt.

Biggest culprit is lack of airflow.
It is a bit scary when your high side gauge pegs itself at 500 psi.

edwinsmith

I meant to put R-12 but my fingers had a different idea. My gauge set goes to 600 psi which is right where the pop off valve is set. Makes a heck of a noise and mess. The oil gets on the belt and squeals forever.

Edwin

NJTman

I officially would love to thank, praise, and now bow down and do my Indian honoring pose to Jim Lane, dodgenstein, and you guys who responded here, on my pressure relief valve thread.


Turns out Jim's response to "airflow" was indeed correct. Cleaned the AC condenser, realigned the damaged fins, removed an air block, cleaned and washed out the soot from 25 years, both in AC condenser and the intercooler. Installed a new clutch for the fan, and my AC is no longer farting spray on my passenger fenderwell.


Is the system low on Freon now? Well, I shut it down after 3 short blasts of that horrible noise, and didn't use it since the repair and cleaning. The system blows cold air, and seems to function normally.


I'm apprehensive about letting anyone mess with it to check, as with my luck, something will go haywire.


Huge thanks again to all of you who helped.