ac charging problems

[hunter1]

The compressor bearing failed again so I changed out the compressor this time, changed expansion valve and dryer and flushed the system. The ac was working before I started but now I can not get the compressor to kick on. I tried shorting across the low pressure switch and both high pressure switches but there is no power to the clutch. Before I replaced it the pulley did cut thru the plug going to the clutch so I thought maybe a fuse but did not find a bad one. Any ideas on where I should start looking?

[speedygonzales]

I would expect a fuse no matter what year it is. Check to see if power is going to the switch.

Incidentally what year, make and model are you talking about?

Make a signature with the information in it.

[hunter1]

That's what I get for posting late at night, I left out the details. It is a 98 chevy 3500 6.5. 4 x4 dually. I have power to the low pressure switch and the high pressure switch on the compressor but no power to the high pressure switch at the manifold. The light in the cab works and the blower runs and the fuse panel only shows 1 fuse for the ac. This thing kicked my rear yesterday so I quit, I will look at it today as maybe I missed something but I don't know what.

[ChevLoRay]

Best I can say is, to the forum!! This place has several helpful folks who can steer you in the right direction. Best for me (personally) to just butt out.

[scotts62]

Information in the sig is still misleading because you can only assume they are talking about one that is in it and that isn't always the case.

There has to be a fuse or maybe a broken wire causing the compressor not to get power.

[iluvmy72]

believe it or not man.......but the climate control units on these things go out like crazy. The boards get shot for some reason. You most likeley have a bad one as have 3 million others in the last 5 years. Plan on spending around 200 bucks or less during this time of year when everyone will be wanting one. If this is your problem that is. But no power usually means a bad control unit. Oh....make sure you find one where they did not break the unit's clips upon removal.....ones with unbroken clips are much less likely to have nothing wrong with them. They can get ruined upon removal. Vibration and impact has been the cause of many of these to go out. I had bought two from different junk yards who said they were both tested and would work but was still "AS-IS" and they were still broken. thye had to be hooked up and working to really test it. Bought one from ebay....same issue but here I believe the guy was lying from the start and knew is was junk. I then found a guy parting out a suburban and his engine still ran but tranny and rear end were shot. So this time I had a chance to see the A/C climate control actually run. I was the first to call on it and by the time I got there 2 hours later, 4 other people had called for the same part which in turn caused him to run the price up by 50 bucks from 150. I paid it and while my friend took it out from his dash, one of the other people who called showed up and was pissed saying he needed it more than me cause of some sob-story about his mom dying soon and he wanted to take his family to Arizona to see her but said he had to have the A/C working for it to happen and then said I was ruining his life.....I told him to go to the dealer and stop crying or drive with the stupid windows down. But that is how crazy finding the part you need can be.

[ChevLoRay]

My boss drives a '90 GMC. He also had no AC/heat. Turned out the control head was bad. O'Reilly's had one and he was back on the road for less than $200....seems it wasn't much over $125.

[Boog]

I may have missed it but I don't see where you've tested the clutch itself. I know you put on a new or reman'd compressor but do you know the clutch works? Unplug the clutch coil and run a 12 volt power to it and see if it engages. Easy to test and don't cost anything. If it's bad it's under warranty. If it's good then you've narrowed the problem even more.
As my dad told me many times a brand new part, or reman'd part, may not work so don't assume it will.

[ChevyTech]

Many control heads get replaced that don’t need to be replaced.

Would you replace the ECM because it got a trouble code set in it?

Low refrigerant causes the compressor to cycle quickly.
Many of the control heads monitor the cycling of the AC, and if it cycles to quickly the control head will no longer allow the AC clutch to engage, to protect the compressor.
Some of the systems have a problem where they detect low refrigerant in error when the refrigerant is not low.

People swap the control head and the system will then engage the AC. If the people unplugged there control head, and did not swap it, but plugged it back in, the memory would be cleared of the low refrigerant detection, and the compressor could engage again.

I have come to the conclusion that it is very hard to help people with Air Conditioning and most people should not be working on AC.

[hunter1]

I have gotten it fixed and from now on you can refer to me as STUPID as thats how I feel. I mostly work on older vehichles and tractors and such but I still can't believe I forgot about the fuse box under the hood. The AC just won't work when the fuse is blown. This is what I thought at the begining but I couldn't find a bad fuse in the fuse box in the cab. It was suggested here that that was the problem and you were right. I am glad its fixed but still DUH. I think my CRS in getting worse. Thanks

[scotts62]

Na dont think that, it happens to us all. glad you got it fixed though

[iluvmy72]

yeah man...no biggie....enjoy that nice cool A/C!!!

[ChevLoRay]

CRS....sucks.