97 mazda b4000 no power at compressor

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97 mazda b4000 no power at compressor

Postby tloftis » Sun Jul 23, 2017 12:43 pm

My AC was working fine (97 Mazda B4000 truck) before I bought a Snap-on modis. I ran a check with the modis and let it run all the checks and it revved the engine up and shut the air conditioner of and on etc… it ran checks on many of the other components… well anyway, my air conditioner never worked properly again. It started blowing cold air during the test. Hmmmm Now it comes on sometimes and sometimes it does not.
I have checked pressure at 39 on low and 165 on high. When it comes on… it is cold and comes out of main vent at 38 deg. sometimes. I have a Mac brand digital thermometer reading it. If it is on it blows really cold.
Once when the compressor cut off, I probed the pressure switch and it had power at both sides. I tested it when the compressor cut off and I had NO power to the compressor wire and had power at both wires on the pressure switch. So my problem seems to be after the pressure switch and before the compressor plug.???
When the compressor was running, I wanted to see which relay under the hood controlled it. I pulled them one at a time while the compressor was running and I could not cut the clutch off. Two of them killed the engine and the third still did not stop the clutch. I am hoping my modis did not do anything to the PCM…

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