97 mustang gt compressor doesn’t come on

[doinstufftw]

Hello team. Brand new here so hello. I’ve replaced every component in the ac system. Vacuumed, system holds pressure, no leaks but when I charge it the hi side pressure won’t go over 100 psi. The lo side gets to 100psi as well sometimes 110psi and it just stays there. And the compressor does not click on. I checked for power to the clutch with a multimeter and it was doing something. I’ll have to check it again to see if it’s getting enough juice. So there’s my problem. Any ideas?

[JohnHere]

Without the compressor running, you're reading only the static pressures. The question is, why is the compressor not coming on at 100 PSI as it should so that you can finish charging the system? It might be something electrical or a clutch problem.

Assuming you're reading about 12 volts at the compressor connector, the clutch gap could be too wide. One way to test for that is to nudge the front of the clutch disk with a wood hammer handle or something similar (watch your hands!) with the system turned on and see whether the clutch engages. If so, you'll need to reduce the gap to around 0.020" by removing a shim or two, which will require removal of the clutch disk. Or, if you can get to it, physically measure the gap by slipping a feeler gauge between the clutch disk and face.

[Cusser]

And the compressor does not click on. I checked for power to the clutch with a multimeter and it was doing something. I’ll have to check it again to see if it’s getting enough juice. So there’s my problem. Any ideas?

You're measuring the static pressure because the AC clutch is not engaging.

Turn on the engine and AC and determine for sure whether the wire to the AC clutch has 12 volt positive or not using DC voltmeter in 0-20 scale. Post your findings, we don't know what "was doing something" means.

If so, issue with the AC clutch.
If not, you'll need to trace the wiring of the AC circuit, including pressure switch(es), relay(s), etc.

[Dougflas]

You can have 12volts at the compressor and a defective connection. Use a test light at this connection so there is a load. Most voltmeters do not create a load.