When I turn on the ac its puts the vehicle in limp mode. ...


When I turn on the ac its puts the vehicle in limp mode. All the fuses are good. With a multimeter I had someone hit the ac button and the battery reading was around 14.7 it should have gone down not up? 2005 Chevy Tahoe 4.8 V8 <...

When I turn on the ac its puts the vehicle in limp mode. All the fuses are good. With a multimeter I had someone hit the ac button and the battery reading was around 14.7 it should have gone down not up? 2005 Chevy Tahoe 4.8 V8 Mechanic's Assistant: Have you checked the Freon level? Yes its good Mechanic's Assistant: Are you fixing your Tahoe yourself? What have you tried so far? Yes fixing my self. When I bought the vehicle the HVAC wasn't working correctly. I replaced the resistor because two wires had been melted on to the plug. The fan speed was not working properly either so I replaced the controller knob. It's all works just when I put the AC on or defrost it immediately puts it in limp mode. Mechanic's Assistant: Anything else you want the Mechanic to know before I connect you? I have an obll scan tool but it's not helpful.

Automotive Expert
Good Morning Is the check [engine](/topics-engine-chevy/) light coming on ? What is it doing ?

Only when I turn on the AC.
Automotive Expert
You will need to have someone check the code with a professional scan tool to get the code and then you will be able to check it . Without that we will be guessing , i am assuming the compressor doesn't come on ? SO it could be a bad compressor .

Compressor comes on but put vehicle in limp mode. Code reads lost communication with throttle control module. I have already replaced the controller module.
Automotive Expert
do you have that code number ?

U0107
Automotive Expert
Here is the test for that code , when replacing the part doesn't work , you just have to start checking the wires

Ok on more thing when I turn on the vehicle the voltage is 14.4 when I turn on the Ac it jumps to 14.8 shouldn't it go down. Could all this be alternator related. Because other than that the vehicle runs fine with no codes
Automotive Expert
Is that with it running ?
Automotive Expert
Yes it should , it may be raising it because it expects the compressor to come on but it doesnt come on and bring the voltage down .

more likely the alternator has gone bad?
Automotive Expert
No i think it working properly , just it doesn't know the compressor isnt coming on

The compressor is coming on. The Ac blows cold it just puts in limp mode. I clear the code and it runs fine turn the ac back on and immediately back to limp mode with the ac blowing cold and the voltage above 14.4
Automotive Expert
you need to check that code , there is a communication problem

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