a/c issues HELP! 92 Cutlass Supreme SL

[Scott205]

Hey guys,

I have a 92 Cutlass and it wont' cool. I noticed the compressor runs and the fan come on, but it doesn't cool inside. I have had the thought it was low on Freon (didn't change after I added a can) put more oil in it (didn't help).

I am currently thinking the air coming out of the vents is a blend of the a/c air and all the hot air from the heater core. Is there a door that controls when the heat comes out? Is it vacuum operated? I did have a good chunk of the top of the engine off, and wonder if I messed up or disconnected a line. Getting ready to take the dash apart inside.

Scott

[Schurkey]

Adding refrigerant oil when none is needed will kill system efficiency. Overcharging a system will kill system efficiency, AND lead to potential explosion hazard when the high-side pressures increase beyond what the hoses and condenser can handle.

Put gauges on that thing, and find out where you are in terms of high- and low-side pressure when the system stabilizes--engine fully warm.

Yes, sounds like you've got blend-door problems. When the vacuum dies, I'm thinking the air flow goes to the defrost vents; but I'm not sure about temperature control--probably full warm.

[Scott205]

Yes, sounds like you've got blend-door problems. When the vacuum dies, I'm thinking the air flow goes to the defrost vents; but I'm not sure about temperature control--probably full warm.

I have some vacuum control because it will go to windshield at 90 degrees, the fan motor changes, but I am thinking the module (valve?) for closing off the outside air or the door (which I believe is a metal rod operated door) is stuck open.

I have a hard time believing that a system can take in too much oil (it is liquid and doesn't compress the same) and can't really put a ton more of r134a considering the original system handles r12 than the system can handle.. most explosions come from a clogged system producing excessive pressures.

[Scott205]

OK, I am thinking this one may be out of my hands.. all the vacuum modules seem to be working, the blend door might not have been perfectly closed but after removing the actuator and moving it manually, it didn't help much if at all. Now I am thinking perhaps the line is clogged with something, or perhaps the compressor, though spinning isn't really compressing. I guess I need a reputable a/c guy now..

[Schurkey]

perhaps the compressor, though spinning isn't really compressing. I guess I need a reputable a/c guy now..

Put gauges on that thing, and find out where you are in terms of high- and low-side pressure when the system stabilizes--engine fully warm.

^^^

[Scott205]

Yeah, but I only have a low side gauge.. oreilly's wants about $96for a set for what they had in the store, I saw a set online at Autozone for $55, going to check into it tomorrow, but I noticed today the low side wasn't getting cold, even though it was a little and the 2nd fan were running the other day.

[Scott205]

Ok, rented the manifold gauge from AutoZone. Low side was 70 psi at idle, 87 at 2000 rpm. High side was 0.

Is this a control valve? or could a plugged orifice tube or accumulator cause this?

[Schurkey]

Ok, rented the manifold gauge from AutoZone. Low side was 70 psi at idle, 87 at 2000 rpm. High side was 0.

Is this a control valve? or could a plugged orifice tube or accumulator cause this?

Compressor probably isn't actually pumping. You didn't get the high-side schrader valve to open. Zero psi on the high side is impossible if you have 70 on the low side. Higher low-side pressure as the engine RPM increases is unlikely, but higher low-side pressure as the engine warms up is reasonable.