cadwiz_01Z

No, the belt does not need to be off to test if the compressor is locked up. The only time the outer (belt-driven) part is coupled to the inner part is when the clutch is energized. I did have another thought. If your problem is in the electrical part of the clutch, you can just replace that. If your a/c was working fine before and the compressor isn't locked up, I don't know that I would do the conversion. But that's just me. No need to fix something that isn't broken.

Bfenty

so the electrical part of the clutch, does that mean I need to buy a new clutch? Or the non-clutch part of the compressor?

JimLentz

First confirm if the compressor is locked up.

belairbrian

neighbor was replacing the compressor and condenser on one of his cars a couple weeks back.

Autozone loaned him the flushing equipment. he just had to buy the solvent. pretty simple set up. You just pour solvent in the can and pressurize with your compressor. We used a tire inflator with a gauge to make sure we didn't over pressurize the can.

The can had a hose and a nozzle. Just stuck it in each line and pulled the trigger.

cadwiz_01Z

Found some replacement parts on the auction site. Looks like you can get just the coil for around $40-$50. You may be able to get the pullers from autozone on the "loan-a-tool" program.

Also, there is a diode in the connector for the a/c clutch. I'm not sure what the symptoms would be if the diode was bad or the connector reversed.

Here is a youtube video that shows the procedure.

WVZR-1

It was suggested way back on page #1 to check coil. I believe that generally speaking that 3 - 5Ω is considered "pass" less than 2 or greater than 5 are "fail". That test is non-destructive so if compressor isn't locked you just test.

Generally speaking a person needs to go back to "where they've recently been" first after a repair if a related failure surfaces. You suspect electrical and you've been everywhere recently, AC command is from ECM I believe through various switches so maybe you just revisit where you've been.

When you were looking for the vacuum tube through the dash did you do anything with the ECM? Maybe move it to get better access?

whalepirot

The following assumes the electrical side checks out.
Few A/C shops really get it right so, good luck with that. IF, you change the compressor, I'd bet the warranty is invalid unless you also change the dryer. Expansion valves are cheap, too, and as long as the sytem is open, at that car's age, I'd change the O-rings.

Proper A/C vacuum gear is not readily available here and checking leaks by vacuum holding, is not 100% guarantee it won't leak under PRESSURE.

I recommend swapping in the above, then having a reputable shop evacuate and recharge the system, IF the system is sealed, with R12, as it was designed.

Do it right; do it once. Then enjoy

Bfenty

There's a short in the compressor. Compressor turns freely with clutch disengaged.

JimLentz

A backward diode would look like a short if it could handle the current. If the diode is marked for the cathode with a line around its body that would go to the positive side.


Cathode on right end.

cadwiz_01Z

All that test was for was determining if the compressor was locked up. It doesn't automatically mean the coil is bad. Electrical gremlins are difficult to pin-point at times. Did you check the resistance in the clutch coil? Did you check that you are getting 12 vdc at the connector that plugs into the clutch? Be aware that you may need to swap the test leads on the contacts to get a reading, due to the diode in the connector.

Bfenty

How does one check the clutch coil? The compressor is still on the car, there's two paddles on the top where the connector goes, I checked there and it looked like a short (almost 0 resistance).

Haven't checked I'm getting 12 vdc at the connector, that would be a stupid simple test.

cadwiz_01Z

Just like that. Resistance between the two contacts that the connector plugs into. Was it "zero", or just close to zero? The pass/fail window on that coil seems to very small and very low resistance (3-5 ohms, which is close to zero).

Sent you an email.

Silver85

If you have a Radio Shack or electronics store nearby I would highly recommend the resistance test of putting a 5ohm resistor in the circuit just to see. Probably $2 maybe?

What concerns me is the possibility of the problem being else where in the circuit but not showing up until the circuit is complete. If we had a short, a fuse should blow or wires should melt. If we had an open circuit nothing should happen other than the AC clutch not engaging. How are we losing electrical to the rest of the car? I think somehow we are affecting the ECM when we call for cooling and causing systems to shut down. Maybe power is dropping off another relay when the AC circuit is closed?

I would want to know that the circuit will work after I spend money replacing components by simulating the load. It very well could be the clutch is the only problem and simply replacing it will solve the problem but it won't be an easy or inexpensive job and I would throw tools and invent new words if I had done it and the problem didn't go away.

cadwiz_01Z

I used to do that but I quit throwing the tools. They always seemed to hit expensive parts.

Bfenty

Radio shack...I hear that was a place that used to exist...

...but seriously they’ve gone out of business around here. I think my buddy might have a 5 ohm resistor.

Cadwiz, it was close to 0-like 0.1 ohms. I agree with you, though, not completely conclusive. If i weren’t concerned about damaging something I’d plug it back in and see if maybe the issue was intermittent-maybe it’s just when it’s hot or something.

I will keep plugging away at this one, might take me a few days to get all of this testing done. Lots going on here. Thanks for all the suggestions I’m learning a lot.

cadwiz_01Z

That sounds like a dead short to me. Did you try the hot-wire test yet? That will be the definitive test.

70ZZ3 96LT4

disconnect the blower motor and see if the engine runs

Gene D

Interesting post.

On my vette. When I turn on the A/C, the fan on radiator turns on. The blower on firewall turns on also.
The only electrical draw for compressor is to the magnetic coil to engage pulley. That should not be much draw, as others have said.
Don't forget about the whole system.
Mine has an auto fan controller turn on also.

Good Luck. Keep us posted

Bfenty

So today I tested with resistors, both 2 ohm and 5 ohm, and everything worked perfectly. I tried just plugging the compressor back in, and the whole thing works. I'm still thinking there's something funky going on with the compressor, but I drove around on errands for a couple hours today with no issue whatever. The FIRST time I turned on the A/C, the dash flickered but that was the only thing that was odd. It's definitely an intermittent issue, which is annoying, but at least the AC is working again?

Gene D

It was suggested by a user to unplug blower motor.

If you have a ground connection going weak.
The blower motor could be pushing the limits of the connections ability.
If there is not enough ground flow, Everything could stop working.
Thinking about your dash/ firewall ground. Would be all passenger compartment controls.