[hottrodd]

i finally reinstalled my factory A/C sys, into my 67gto, pulled vacuum on the sys. for 45 min. charged it, starts running fine then in about 10-15 min. the compressor start acting like its locking up, causing the clutch to slip, as this is happening a/c stop cooling, I immeditely shut it down,. a hour later I went out to check the compressor out, the a/c turns over by hand not seized up, or showing any issues. started car , started car a/c turned on fine, cooled down fine, then in 10-15 min. did same thing, a/c compressor acts like it locking up compressor clutch turn slowly & stiffly. I shut car down. its a hour later, checked compressor again, it turns over by hand easy.
Im still running a POA valve, i readjusted it for 134r.

is the sys freezing up,or the poa valve bad, need readjusted again??????, or expansion valve bad??? possibly moisture still inside?
all parts were new, but the poa & expansion valve were both used original units.

i've installed sanden 508 a/c systems . in many hotrods, never had any issue,
this is the first time Ive used 50 year old a/c setup that was made for r12 originally.
I dont want to tear up anything, but but have any idea what to check or how to eliminate parts as possible culprit.

[Goatracer1]

What are your pressure readings when it happens? Are you still using oil for the R12 with the R134A

[hottrodd]

I put new oil in new compressor pag 100,11 oz.
With the little gauge on the a/c bottles u get at the auto parts store( don't have access to a real a/c manifold gauge set until next week) read 40 psi when working fine, when the compressor starts freezing up/ locking up the pressure rapidly starts climbing to over 80, didn't stay any close to car, was afraid something might blow, when I came back in a hour & everything has cooled down , started car, turn on a/c , the guage showed 40 psi , went for a drive, stopped in 8-15 min. When a/c started gettin warm put gauge on was 80-90 psi, shut a/c . When I got home 1/2 hour later I checked the a/c. Turn on fine shows 40 psi. Blows ice cold air again. But I shut car off & posted this to find out what's wrong ????

[GOLDOHC]

Could be an overcharged a/c system, or not enough air flow through condenser. Fan clutch?

[66sprint]

I would not run it for long at all unless you have a high side gauge attached to see if the high side pressures are going off the scale.

You are dealing with pressures ranging from 250PSI and up on a properly running AC system. If it is overcharged or insufficient airflow is causing enough of a problem to stall out an A6 compressor your high side may be dangerously high (like 400PSI or more).

Be careful and if possible, have it checked by someone who knows AC systems.

Chris