Hi Group.
I have a 2006 H2 with 250,000 miles. My AC went out. Took it in to a GMC dealer. Said AC fuse was blown. Replaced it and it blew again. They bypassed - something - and said the compressor was OK and freon was OK. Said it must be the fuse box. Does that seem right? Thanks in advance.

JohnD

 

Welcome to HF. The New Member Section is not for Tech questions and strictly for intros so this was moved to the H2 section.

In an 18 year old truck, electrical corrosion can be the problem. Like others have done, might need to take apart the fuse block off the tray and clean all the contacts.

 

I'm really surprised the GM dealer would "bypass something." (Lol, like maybe the fuse itself?) The last thing you need is a hacked wiring harness, especially from a dealer. Any hacked wiring harness can create troubleshooting issues later down the road where the schematic won't match what you have. I definitely want an explanation in detail...
... But maybe that's just me?

 

Thank you, Doc. Good observation. The truck is from Michigan and has a patina of rust on the undercarriage and running boards are rusted. I am nothing close to a mechanic and would be afraid if the H2 ever ran again if I dug into it. :-)

 

Thanks, Robert. Service guy did say what he bypassed to "jump" the compressor but I can't remember what he said. Before the AC went out, I had the radio replaced. Touch screen on the original Kenwood was gone - actually gone when I bought it. I replaced it with another Kenwood and all the installer had to do, in my estimation, was to unhook the original wires and hook them to the new radio. He had the panel on the driver's side dash removed, for some reason. From SOCAL to Joplin, MO the dash lights were going on and off. In Flagstaff, the radio never turned off - ran all night. Radio shop in Joplin reset the radio and it goes off with the ignition. I complained to the guy who installed the radio and he said my harness had been ;hacked'. Nice to know 1,000 miles away . . .

 

That's easy to decipher what he jumped. Standing at passenger side fender with a hood open, look at your AC air dryer on the firewall. It's that round aluminum thing. Look for a sensor screwed into it, with a connector that has two wires. That's your low pressure sensor. What it does is prevents the AC from coming on if it does not sense adequate refrigerant pressure in the system. Common test is to unplug it and jump the two wires in the connector. Paper clip or small wire will do it. If you have adequate refrigerant pressure and jumping those two wires enables it to work, then that sensor is defective. They're fairly cheap and universal across most GM vehicles. You can unscrew without losing any refrigerant. There's a check ball behind it to prevent everything from leaking out when you remove it. Take it to any auto parts counter, they should have it in stock. Should be between 5 and 10 dollars.

 

FYI.... If you're a thousand miles from home, keep driving with that connector jumpered. No real hurry to replace it, but keep in mind if you develop a refrigerant leak and lose pressure your compressor will still operate with that connection jumpered and burn itself out. (That's the purpose of that switch, to protect the compressor)

 

Wow, Robert. That would be great if that is what the problem is. Will call the service manager and find out more what tests they ran. They said the fuse box needed to be replaced and it was special order . .. S1,013.00 later, I think it is mine. I balked at having it installed once and he will ship it back with me paying the postage. H2 is in my garage now - working on the rust on the running boards. Will take a look at the Air Dryer. Thanks so much for your help, Robert.

 

That's really the only way to jump something to get the compressor to come on. And it's not in the fuse box.
With that said, you might also need a fuse box anyway depending on how much corrosion is there. You might want to confirm with them that they didn't bypass any fuses.... I really doubt they would do that, it could burn down the vehicle really quick.

My guess is they cleaned the circuit in the fuse box for your AC and the compressor would not come on.... So then they probably jumped the sensor at the air dryer after confirming you had enough refrigerant.... And if that triggered the compressor, that confirms it's the sensor. That's the more plausible reality of what they did. I don't think there's any way in hell they would want to risk burning your vehicle down, LOL.

 

Note: You also have a high pressure switch, to shut off the compressor if the pressure is too high like from being overcharged with freon. Standing at the passenger fender, look at one of the ac lines that go around the passenger side of the radiator. You'll see another sensor there it's also replaceable and will not leak freon if you unscrew it. I would replace both at the same time, inexpensive.