I need some help with my 2003 hummer H2 air conditioning. Most of the time the air conditioning works fine. However, sometimes the compressor clutch won’t engage at all. I’ll turn on the AC on the climate control unit and the blower etc. comes on but the air doesn’t blow cold. Usually I’ll turn off the car and restart it and then it will work. Here lately it has been getting worse though. Resort in the car doesn’t fix it and sometimes it will just all of a sudden start working while I’m driving. Usually I’ll turn off the car and restart it and then it will work. Here lately it has been getting worse though. Restarting the car doesn’t fix it and sometimes it will just all of a sudden start working while I’m driving.

The pressures are great. It doesn’t have a leak. I replaced the interior climate control head unit about a year ago with a dorman unit from oreillys.

It is definitely something electrical but I was wondering if any of you guys have seen this problem before. I was thinking it may be an AC relay or a switch of some kind. I’m also not ruling out that the new interior head unit sometimes doesn’t send power to the correct place to get power to the AC compressor clutch.

If anybody has any ideas or common problems to check, please let me know. Obviously the fuses are fine because it works most times.
Thank you for your time.

 

bad connection at the low pressure switch or a bad switch, these are a very common failure point and easy to check,

Easy to check, either wiggle the connector next time it will not turn the compressor on or jump the switch and see if that kicks it on.

I have to admit that I don't have any faith in the Dorman replacement modules, I've had many fail straight out of the box,

Neal

 

Also be aware - the AC snowflake icon on the earlier units when visible means the AC is OFF (has a hard to see slash through it). That was confusing so GM updated the module to where the AC snowflake icon had no slash and if it was visible then the AC was on. Probably not the issue but did confuse a lot of people back then enough that GM changed it since you would hit the AC button, the snowflake would appear and you would assume it was on. lol

 

Replace the external temp sensor under the hood by the right headlight. You can find part on amazon. See if that works.

 

Thank you all so much. Lol. I know what you mean about the snowflake. It confused me when I first got the car. That’s not the problem but I know what you’re saying.

Thank you so much for the information on the low pressure switch. I am going to replace it. And check the wiring as a precautionary measure.
I also look into the sensor by the headlight like you recommend.

Here’s what I found so far. I removed the fuse, cleaned the connections and put it back. I changed out the compressor, clutch relay with another relay and made sure the connections are really clean.
I wanted to give it some time before I reported back. It has been working every day multiple times a day and hasn’t once stopped working.
I’m still gonna service the other parts just to be safe. I’m just extremely happy to have a good working air conditioning again. My H2 has always had super cold air conditioning which I love. Thank you all so much and I’ll report back if anything new transpires.

 

thanks for letting us know you have the issue resolved, it very well could have been the fuse connection or an issue with the clutch.

Glad you got it working,

Neal

 

Nice job. Mine kept throwing belts this past week. Had to replace the tensioner. Should’ve done it a long time ago lol.

 

After replacing my compressor & condenser, and still having the intermittent cold/not cold issue — I replaced the INTERIOR AC switch (Amazon Doorman Climate control switch 598-211XD) and finally AC works. A few weeks later, problem recur, Amazon exchange with another (thanks Amazon), and it’s been great for 2 years