AC Quit

[Bigfish95971]

I found the dash control to be ok but the pin connections on the Buss wire on both the PCM and dash control contact looked flattened out and I bent them back an I think that fixed that . But I believe I had shorted out the the coil messing with it. Plus I found a bad ground wire on the coil main harness plug. Maybe I did or was problem all along. Replaced end plug. Now everything works. Relay sends juice to could but that shorts out the fuse, so coil is shorted at this point.
Was the video fairly accurate for your 95 which is same as mine.

 

[Bigfish95971]

Finally got tools and differnt clutch and coil installed. Still no cool and blowing AC fuse. Can a bad pcm blow the fuse? Other ideas?

 

[Bigshawn]

You u say have a code coming up that it's not communicating with PCM? That would have been the first thins i went too. Get the wiring schematic for your pcm and check the pin for your ac/compressor. Make sure you disconnect battery. But u find the pin and make sure it's in there right and not burnt etc. If you can't get it communicating you might need to get a new PCM.

 

[Bigfish95971]

I can not pull that code with my little tool. A shop said I had that one. i substituted a heater control unit, no help. I had the schematics. I pulled the control unit and PCM and check that bus wire and pins. The pins looked good but the flat contacts on the in it side looked flattened out on that wire so I bent it back in a bit to make contact on both.

At some point when working on fuse box and relay I shorted something and made a small bit of smoke. Thought it came from the solenoid or it wire but apparently not after replacing that. Ground wire on solenoid plug harness was broken(I may have don that working on it) but no burnt insulation. Replaced that plug with new one and did good clean job.

Sometime around that point it started to blow that fuse when turning on the AC. Could my short and no bus be inside the PCM? I am thinking either there or in the wire down to the solenoid from fuse box to solenoid for the short?

I have to google and reprint the schematics, the ones I had got soaked from a leaking ice chest. I want to check that green wire to the solenoid for shorts next. I hate diagnosis by parts replacement, but it has comes down to that. I can get a PCM for 60 bucks, a lot better thatn 600 on my Dodge. Not until payday though.
Any other thoughts on the short?

 

[afpj]

When you substitute the heater control unit out, do you mean the HVAC control unit? And you said a used one, a used one from where? It is my understanding that most used HVAC head units require programming to your specific truck using a bi directional scan tool. For example, I got a dorman used unit but found it had to be programmed so I had to get a new one at a higher cost since I was in a time crunch and didn't have capability to do the programming.

 

[Bigshawn]

I'm not the best when it comes to wiring and stuff on a vehicle. That's one thing I've always disliked and is a pain for me. I wish I could help you move but I'm limited in knowledge about it. Have you gotten it fixed yet bud. I'm trying to think of anything else

 

[Bigfish95971]

Thank you both of you. I do not believe the control unit needed programming, It seemed to work the same as the old one. Turned everything on. I fixed a loose pin on the buss wire. Still just no clutch engagement. Finally replaced clutch still not go.

One time when working on fuse box I got a bit of smoke(hope it was not in ECM, truck runs fine) and found a bad wire in the Clutch harness plug. Replaced that before the clutch.

Now whenever I turn it on the AC 10a fuse blows.
I got tired of fighting it and have been operating in 105* with 4/60 air only.

The only thing I have left to do is to unwrap wires and trace the wire from the ecm to the clutch for a direct ground short. But I was tired of it and quit on it for a while.

I have my 99 Dodge Cummins that needs a trani rebuilt for it and have decided to get working on that so I can go back to driving it. When running it is a lot cheaper to run at 21mpg than 15 on this Chevy.

Has any body found a direct short that blows that fuse? Where was it? Has it ever been inside the ECM/PCM Differnt clutch and coil did not help.

 

[nonickatall]

Is a basic OBDII all I need to program new sensor.? It is my understanding the bad sensor blocks Jumping the pressure switch to turn on the clutch. So I will try the clutch jump it I can get to it, Any trick to get to it?

You don't need obd II at all, to test the pressure switch, and there is no sensor. The pressure switch is the sensor, so to speak.

An AC is very simple. The pressure switch pass through, if enough pressure is in the system. These prevent the magnetic clutch to engage, for the compressor is not running at an empty system and getting damaged.

But also the controls, or the control unit, or a fuse, or a relais can be the problem, when the magnetic clutch not engages and the compressor is not started.

In 90% of all cases the system has not enough System pressure.

So the easiest way is to measure, if your pressure switch is open with a multimeter. If not, the most likely issue is, that you system has not enough refrigerant.

If your switch is open and your compressor will not start, it can be a problem of the control, the magnetic clutch, a fuse, or the compressor relais.

The easiest way to check that is, to put 12 volt on your compressor. If the magnetic clutch engages and you have cold air in your car, then the compressor relais, fuse, control unit what ever is the problem.

If, then check your compressor relais with your multimeter.

Do that and write your results...

 

[Bigfish95971]

At this point I believe everything is working and the relay is sending juice to the Compressor coil, but it is shorting out before reaching he clutch and blowing the fuse. I can try jumping the clutch directly again and see what happens. I also heed to test the wires for a direct short. Was hoping others have had fuses blowing and tell me where they found the problem.

 

[TollKeeper]

You can try going directly to the AC clutch, with a fused wire. If the fuse blows, then either you did something wrong, or the clutch is bad.