AC Quit

[Bigfish95971]

Sorry about that I do not know what the pressure was. Thank you for responses so far.
Let me update with the same post I put on my other forum. Not no response, just not one that helped with right answer yet. Did everything suggested but had to to take to shop for some. Thought I would have seen more with same exact issue and their answer. Not yet.

Questions?
Can Fluid be vacuumed out and refilled at a shop without the clutch/ compressor working?
Gave up and took it to a shop and had it Checked and "diagnosed". $175 later, They said they evacuated it and refilled it and put in 2 new Schroeder valves(valve cores i guess) for 20 dollars each,(one blew out and they had to do it again)They said it had a code for "no communication between the PCM and AC control unit"? Did not catch number. They said it needed new heater control unit. I replaced with matching used one and did reset. Still no love. Put old one back in.

Jumped low side sensor so far has not helped. Had 4.8v to it. Does it go directly to the clutch through the relay or through the PCM or something else?

Next I am going to jump the clutch coil while running. I did it before not running.

What is next? New PCM? Is used Chevy one plug and play? Does anybody around Yuba City, CA, have a sophisticated Scan tool that that can help me?
Does anybody know a Chevy truck(rather than Tahoe) forum that gets more attention than the one suggested above?
Other thoughts?

 

[Bigfish95971]

OK I have narrowed it down to two things, I need a new plug to the harness wire to the solenoid because I broke off the ground on it. Got that here now.

Now the real problem all along, the system seems to be working correctly but the solid green wire from the PDC relay to the clutch solenoid is not getting power from the relay. The relay is working and closing to send power,(and when jumped) but it appears to be open(bad connection to the green wire.

The question is how do I connect it or replace it? I have removed the cover and turned over the PDC to the bottom, I have found the wires, I believe, but how do I get to the connections to fix or get power for anew wire?

I pulled the bolt loose on that center black block and it would only come part way off, decided not to force it any further?

What next, help or video?
Its going to be 105 to 115 the next few days.

 

[Bigfish95971]

Further the green wire works, the relay is not grounded and wont close.

More info,

• a moment ago
• 
  
  GROUNDS!
  
  What do you know about grounds on a Chevy and on the relays in all fuse boxes?
  
  I have juice to the always hot post of the relay.
  When the car and AC are turned on and running(no cold) there is power to the input trigger wire.
  Can not get the (or replacement) relay to trip.
  I have the PDC flipped up bottom up.There is a pair of black and white wires on a hole between the two hot wires, solid green and green /white. I think it is ground from the low pressure sensor/switch which I think is working. It does not trip the relay even if I ground those black/white wires to direct ground.
  
  Any Chevy experience, Ideas?
  Thanks.

 

[Bigfish95971]

Anybody still with me? Down now to replacing the clutch now, coil has been shorted out. Anybody changed one in the truck, I have access to the tools on rental. Any tricks to access and replacement with the compressor in place?

 

[nonickatall]

YouTube is your friend...

 

[Bigfish95971]

Thanks, it must be morning over there. You know any Dodge guys over there from Dodge forum?

 

[nonickatall]

It wass 11:00 am so after third coffee.
How do you come on Dodge?

 

[Bigfish95971]

I have a 99 that I post on hours daily in 2nd gen sections helping people daily. There is a gentleman now in Germany goes by Ukraineram on the Dodge Cummins Diesel Forum site that. He moved to Germany after the war started. He is building a badass 3500 somewhere in Germany where his company moved him.

 

[Bigfish95971]

Is the front end shrouds and so on the same on an 03, that looks older?

 

[TollKeeper]

A little late to the party, so.. Mine is for a 1995, so a different system. But I found it relatable to your condition.

I had the same issue on a 95 Silverado. The catch was that if I turned on the defrost, it worked (as it should be default), but not in any other mode.

By default, if the system meets the requirements in the various sensors, defrost will always turn on the AC unless the ambient air temp is 18* or lower (if memory serves).

Mine was the actual switch inside the dash controller head unit. It would light up that the AC was on, but it never actually made the physical connection to turn on the AC compressor.

I replaced my dash controller head unit, and it worked perfectly from then on out.

On your 2003, there are different modules involved, from the dash head unit, to the climate control module, ambient outside temp, interior ambient temp, driver ambient temp, and who knows what else.

 

[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.