dcmeigs
New Member
My A/C suddenly stopped working yesterday on my 91 MTX. In Phoenix, that's never a good thing.
Most problems I've had with A/C are resolved with freon or a new compressor or clutch. This seems different.
I am getting proper suction pressure and the high side is getting too hot to touch going into the condenser yet I'm not getting cool cabin air. I drove it over to a local A/C guy and the pressures on both sides looked OK to him. I kinda got the mechanics shrug and a suggestion that the problem might be behind the dash; 50-50 chance. He didn't seem confident; it didn't seem wise to leave it with him.
So I went home and did the EATC diagnostic and got the 888 with everything lighted. The Blend door seems to be cycling properly and I'm getting vacuum. I can run the temperature up to 95 or whatever and it starts getting even hotter. When I run the temp down it returns to ambient. I even put a clamp on the heater hose to stop flow to the heater core to rule out that possibility.
The temp out the vents is 94 and the temp into the blend box is 96. The two degree drop is repeatable.
I could learn plenty by feeling the freon line after the expansion valve. I've tried to follow the high pressure line back to the cabin but I'm embarrassed to say without success. If someone could tell me the location of the expansion valve and where to look for the high pressure supply line where it passes into the cabin, that would be very helpful.
Of course, I appreciate any theories and troubleshooting tips.
Thanks
Most problems I've had with A/C are resolved with freon or a new compressor or clutch. This seems different.
I am getting proper suction pressure and the high side is getting too hot to touch going into the condenser yet I'm not getting cool cabin air. I drove it over to a local A/C guy and the pressures on both sides looked OK to him. I kinda got the mechanics shrug and a suggestion that the problem might be behind the dash; 50-50 chance. He didn't seem confident; it didn't seem wise to leave it with him.
So I went home and did the EATC diagnostic and got the 888 with everything lighted. The Blend door seems to be cycling properly and I'm getting vacuum. I can run the temperature up to 95 or whatever and it starts getting even hotter. When I run the temp down it returns to ambient. I even put a clamp on the heater hose to stop flow to the heater core to rule out that possibility.
The temp out the vents is 94 and the temp into the blend box is 96. The two degree drop is repeatable.
I could learn plenty by feeling the freon line after the expansion valve. I've tried to follow the high pressure line back to the cabin but I'm embarrassed to say without success. If someone could tell me the location of the expansion valve and where to look for the high pressure supply line where it passes into the cabin, that would be very helpful.
Of course, I appreciate any theories and troubleshooting tips.
Thanks
