95 lesabre a/c clutch issue

The a/c clutch went out(clutch started to freeze up) on my 95 limited (65,000). I replaced the clutch assembly with a new part. Prior to this the a/c worked fine, clutch would engage and disengage on demand. Since replacing the clutch, it will not engage when turning the a/c on or going to the defrost setting.i have checked/replaced fuse for the a/c on the drivers side fuse box. Checked/replaced fuse for a/c controller on passenger side fuse box.also under the hood in the maxi fuse box i have checked the a/c fuse as well as the relay. I flipped the relay with horn relay.i use my test lamp to make that i was getting power (12v) to these points. I also jumped the low pressure switch as well as the high pressure switch all to no avail. I found that i have no power to the low side switch or the compressor.i have no shop manual and am not at all familiar with dash controller system. I have temperature displays,vents all operate on demand. Checked freon low side at about 30lbs static.any ideas on where or why i could be losing power? Thanks

have access to 1998 hvac diagram. auto or manual system?

Remember the ac will not engage below about 35-40 degrees, is it cold there when doing this?

The climate control system is automatic.also i believe that the a/c compressor is used when you select the defroster.

Not at low temps, mine does not , nor any late model GM cars I have owned or worked on.

I thought that when using the defogger that the compressor would cycle to dehumidify the air ? Also someone mentioned to me that it is possible that the climate controller may need to be reprogrammed. Not sure anyone have any info on that.

I have three 92s. They are possibly similar enough to the 95 that the basic circuit for the AC is maybe similar (there is more than one AC system for the 92--a basic system and a dual system.)

Here's what I suggest:

1. Determine if you have power at the A terminal of the pressure cycling switch (on the accumulator) with AC on, fan on high, car running.

Yes? Jump the pressure cycling switch wires with the harness disconnected, AC on, fan on high, car running.

No? Run a jumper wire from the battery or any 12V source to the B terminal of the pressure cycling switch wire harness with the harness disconnected and the AC on, fan on high, car running.

2. Now, is your clutch engaged?

Yes? You have no power to the pressure cycling switch. We can then trace it back first to the high pressure switch (power to it? Yes, it is the switch, No, trace it back to the AC controls, or if dual AC then to the HVAC programmer, then back to the AC controls.)

No?
a)Does wire B from the AC clutch harness have continuity to ground? Yes, it is wired correctly. No, there is your problem. Fix the wire.
b)Do you have power to the A wire in the AC clutch harness (still with the AC on, etc.)? Yes? Then you have a bad clutch or compressor. No? Then trace it back to the AC compressor control relay. Do you have power at the dark green wire with it connected and the AC on? Yes? You have a bad wire between the relay and the clutch. No? Check the operation of the relay. Swap with a known good relay. Also, is fuse 5 in the relay center good (under the passenger side dash.) Is there power to the AC compressor control relay pink and black wires? Yes, good. If not, there is your problem (they should have power in run, or start and come from fuse 5 mentioned above.)

After all this if the wires, compressor, switches, relay, and AC controls check out look to your car's computer. It is very unlikely to be the problem, but it is possible.

The above tests will bypass the AC controls and therefore you can partially determine whether it is possible for them to be bad. If you have a car with an HVAC programmer it is trickier than a simpler electronic system.

The 95 may have a totally different system and if so I apologize for wasting your time. Please ignore this if so!

You may want to adjust your testing to simply first determine if the AC clutch will engage when given power directly to it. You can do it by making sure the B terminal is grounded and then give power to the A terminal. If your clutch engages it is probably fine, if not, there is your problem.

Note that I realize you already did some of these tests but doing them in a systematic order can be helpful. The fact that you found no power at both the low pressure switch AND the AC clutch makes me think it could be the AC controls or the PCM or the HVAC controller. (but did you check for ground on wire B on clutch?)