New AC Compressor will not energize

novaman83 · Post by **novaman83** » 07 Sep 2017, 17:26

We replaced the AC compressor, drier, new expansion valve, all o rings. System was evacuated and filled with R 134a.
Clutch will not energize. We ran a wire directly to it from the batteryand it does energize.

Checked all fuses in the circuit and put in a new relay. No change.

AC was working sporadically before all the components were replaced.

How does one check the high and low pressure switches?

What is next step in diagnosis?

NOTE..B+ battery cable was in bad shape in the fuse box...changing tomorrow. Everything electrical works except the clutch. Would a crappy b+ cable prevent the clutch from operating?

Post by **abscate** » 07 Sep 2017, 18:37

If you ran a wire direct, it's a bad clutch. Sounds like a bad new part

novaman83 · Post by **novaman83** » 10 Sep 2017, 10:37

I replaced the B+ cable as the next step in diagnosis. Yup! That was it!!

Cable end in fuse box had green wires and insulation melted.
Evidently, the voltage drop from battery to fuse box was so great clutch could not be energized.

BTW, nut on B+ cable was only finger tight. My theory is heat/cool cycles loosened the nut and that led to arching which damaged the wiring by overheating. B+ cable was replaced in 2013 by a guy I really trust. I am 99% sure, that nut was tight when he installed the new cable in 2013.
Check ever 6,000 miles or so to be sure nut is tight and use dielectric grease on both ends.

Post by **scot850** » 10 Sep 2017, 10:57

That is exactly what my 'B' cable looked like. For some reason it affects the 99-00 more than earlier cars, although earlier ones should also be carefully checked. Biggest issue is you cannot really see the affected area without dismantling the main fuse box. One tell-tale sign is the top flange end of the cable under the nut discolours from shiny copper to a dull matte finish.

Neil.