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Aran
Aran, General Motors
Category: Chevy
Satisfied Customers: 635
Experience:  Chevrolet Technician
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ac wont come on and at the same time the temperature gauge dose

Customer Question

I have a 2007 HHR. Sometimes the AC won't come on and at the same time the temperature gauge dosen't work. Everything else seems to be working. Any clue what could be causing this?
Submitted: 5 years ago.
Category: Chevy
Expert:  Aran replied 5 years ago.

Customer:

Hi thank you for the question, in your description you mentioned the temperature gauge not working, are you referring to the outside air temperature, if so what is it reading. Thanks.

JACUSTOMER-cehqnxwd- :

The engine temp Gauge is not working. The gauge does not move off 0.

Customer:

Hi thanks for the reply, so the engine temperature gauge reads 0, to clarify does it start that way from startup or could it be working normally and then go to 0? Also when this happens does the check engine light ever come on? Has any repairs been done to try and correct this issue? any additional information you can give is greatly appreciated,

JACUSTOMER-cehqnxwd- :

Sometimes the temp guage works at start-up and goes out later, sometimes it doesn't work at start up and begins working at some point down the road. The engine light is on some of the time, but doesn't seem to be consistant with the temp and AC not working.

JACUSTOMER-cehqnxwd- :

The car has not been in for service to correct any of thes issues.

Customer:

Hi thanks for the response, If you are close to a local parts house like autzone or checker they can scan the computer codes for free, I would be curious to see if there is a coolant temperature sensor code in the engine computer, if this is the case, it would disable the a/c from coming on, is that a possibility to get the codes scanned? thanks.

JACUSTOMER-cehqnxwd- :

I can get the codes scanned. It may be tomorrow before I get back to you.

Customer:

No problem, I am just trying to narrow it down a bit on possibilities of the cause, Thanks.

JACUSTOMER-cehqnxwd- :

I was unable to get the diagnostic codes yesterday. I did a little trouble shooting and found that disconnecting the Temp sensor resulted in the same syptoms that I have been having. So I bought a new sensor and replaced it. I disconnected the battery and cleared the code. About 15 minutes into my drive to work this morning the temp guage and AC stopped working, but no engine light.

Customer:

Hi thanks for the update, I checked coolant temperature sensor codes and they are type b dtc's which means it will turn on the check engine light after two consecutive failed ignition cycyles, which means today when the gauge went to zero, it was the first failure and would not have turned on the light. I suspect that it would have that code in the engine computer, just by the symptoms you induced by unplugging the sensor. I would be suspicious of a broken wire or poor terminal connection somewhere. Can you tug on the wires by the sensor and see if any of them feel like a rubber band, stretchy, if you find a stretchy part that is where the wire is broken. Thanks.

Customer:

Hi again I just wanted to make sure on the coolant temp sensor, does the one you replaced have 2 wires going to it a tan and a yellow? Also from the sensor it is a straight shot right to the ecm there is no connectors in between. Here is a schematic to reference in pdf format if you need it, like I said the most common areas to break is where the wires are not in the loom, on bends or right by the sensor, or at the sensor.

JACUSTOMER-cehqnxwd- :

Thanks for the diagram. The new sensor is 2 wire appears to be the same as the old one and it does work. I talked with someone local about the problem and was told to check the thermostat. I pulled the thermostat and found the rubber seat to be damaged so I replaced the stat. I have run the car about an hour since replacing the stat and everything is still working. I can understand turning off the AC when the engine is overheating, but I can't understand disabling the temperature gauge if the engine is overheating. I think you put me on the right track to finding the problem, I am going to accept your answer. I will let you know if the problem is not resolved.

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Expert:  Aran replied 5 years ago.
Thank you for the reply and accept, for what it is worth here is my opinion. I have trucks come in all the time with the temp gauge at zero and no check engine light, however when the computer is scanned it has a code po128, which is the computer detecting the engine not getting up to operating temperature, or a bad thermostat. It is a default when the code sets to zero the gauge and bring up the engine overheat message, as a precaution the ecm disables the air conditioning as a self protection. Now to your hhr, I can only assume the same, however only going by symptoms and not by trouble codes, gm did not ever mention in the code descriptions once when the engine computer detects its not up to operating temp it does the same on a hhr, otherwise believe me I would have went down that road much sooner. Let me know, Thanks.

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