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Q: A/C not working

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The A/C keeps going in and out. When it stops blowing cold air the temp gauge on the dash drops to C and stays there. When it's working, the temp gauge is at normal level. The relay fuse thing has already been replaced. What could my problem be??

My car has 96000 miles.
My car has an automatic transmission.

In the future, please include the motor size. Thanks.

Because your A/C stops working when your temperature gauge quits as well, this is most likely a problem with the power supplied to your blower motor and your instrument cluster. I suspect the A/C is still actually working, but the blower motor that blows air out of your dash stops working.

If the blower motor continues to blow air, just not cold air, then it points to a different problem. The temperature gauge is part of the instrument cluster that receives information from the ECM (engine control module) in order to display the correct temperature. The BCM turns on your A/C compressor with input from the PCM. With two modules, several sensors and a few switches and motors involved in this system, it will require direct, in person diagnosis to know for sure.

If only the temperature gauge is failing on the dash, this suggests the instrument cluster is ok. If there were a power supply problem, it would affect more on the dash then just the temperature gauge. I’m thinking it may be the temperature sending unit. This will of course affect the gauge, and if the computer thinks the motor could have a temperature problem, then it will shut the A/C off. The best way to check this is with a scanner. A simple code reader from your local auto parts store may work as well. Keep in mind, you will need it connected while the failure is occurring.

If you feel you still need assistance, I recommend having one of our mobile technicians come to your home or office to diagnose the issue with your A/C.

Good luck!

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