The Chevrolet Blazer (4WD model T-10) and its rebadged variant, the GMC S-15 Jimmy (4WD model T-15), are compact/mid-size SUVs manufactured and marketed by Chevrolet and GMC from 1982-2005 across two generations.

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Why won't my AC send signal to the AC Compressor?

2001 Chevy Blazer LT 4WD V6 4.3L

EDIT3: Since I replaced the switch, I’m led to believe that the only other things it could be are either the AC accumulator or the HVAC actuator. The actuator failing is a common issue with this type of car according to online resources, however, that is the more expensive of the two options. I may have to replace the accumulator to see if that works since it only costs $30. If there are any more suggestions or ways to properly diagnose, I’ll gladly try.

EDIT2: I replaced the low pressure switch and it still hasn’t fixed the issue.

EDIT: I just found a video where someone also bypasses the relay. This is exactly what I did, and this gentlemen seems to be having the same exact issue.


Hello. So I went to recharge the AC in my vehicle and noticed that the AC clutch wasn’t spinning at all. I did some troubleshooting, and I now think it has something to do with the computer in my car.

Things I’ve Tried:

I checked every fuse in the car. Replaced one for my cigarette lighter, and all the rest are fine.

In the engine fuse box, there’s a AC fuse and a relay. The fuse is good, and I used a multi-meter and a 12v battery to test the relay, but just in case, I also swapped relays with the horn to make sure they both work. (They do).

Lastly I used a paperclip to bypass the relay on the fuse box, and the clutch started, which leads me to believe that the relay is not being triggered when I tell the car to turn on the AC.

Things I’ve Ruled Out:

  • The AC Compressor/Clutch
  • The Fuses
  • The Fusebox


I’m not sure what else is left to try, but it’s going to start getting hot soon, and I’d really like to have my AC working.


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@fletchertime what is the exact year, model and engine size for your Blazer?


2001 Chevy Blazer LT. V6 4.3L


Make sure the that the connector on your ac is seating properly.





Hi @fletchertime ,

Found these two circuit diagrams online, here which may be of some help.

The first is for a 1998 Blazer, the other doesn’t say what year so hopefully one of them may be the same as your model.

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(click on images to enlarge for better viewing)


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Hello thanks for your help! This helps me a lot in diagnosing, and I think that I have narrowed my diagnosis down to two remaining options which I have highlighted in my 3rd edit.


Hi @fletchertime ,

Don't know your vehicle but can you scan (or get scanned) the OBDII port to check for any error codes?

Not sure if they will have any for the HVAC but if they do it may also be of some help in narrowing it down further

Just a thought.


I had it scanned. No errors to report unfortunately. Someone on Reddit said that these Blazers are prone to leaks so I'm looking into buying a leak test kit when I can afford it.



Here’s an update. I took it to mechanic. Turn out it’s not an electric issues at all. The drier canister is bad, and wasn’t pushing the refrigerant to the pressure switch. I’ll be purchasing an AC kit for the vehicle and replacing the whole AC system. I will update if this works.


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