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Pete, Auto Service Technician
Category: Chevy
Satisfied Customers: 28251
Experience:  14 years GM dealer Technician.
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I have a 2007 avalanche ltz 5.3 and when I turn the a/c on

Customer Question

hi! i have a 2007 avalanche ltz 5.3 and when I turn the a/c on just blinks then light but dosen't work
JA: Sometimes things that you think will be really complicated end up being easy to fix with a Chevy. The Chevy Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best.
Customer: I have a 2007 chevy avalanche the air conditioner does not work properly. the a/c light on the control knob blinks about three times and goes off and does not turn the compressor on
JA: Are you hoping to fix this yourself?
Customer: yes
JA: Great! What have you tried so far?
Customer: nothing
JA: Is there anything else important you think the Chevy Mechanic should know about your Chevy?
Customer: nop
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Chevy Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Chevy
Expert:  Pete replied 1 year ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

If the outside air temp is colder then what the ac compressor is designed to run at ( to prevent ac evaporator freeze up) the ac light flashes 3 times then shuts off and no ac will occur.Usually this is a temp of around 50 degrees or less.If your outside temp is warmer then this and your ambient temp display (outside temp display) is reading the correct outside temp this indicates that the heater/ac controller has detected a fault with one of the heater/ac components and is causing the light to flash and disabling the ac like this here.

What needs to be done from here is to have a scan tool plugged into your vehicle that can read all computers in your vehicle (as some are designed to only read engine codes which will not work here) to see what codes are set for the heater/ac controls.Usually this would be a code that starts with the letter B.

Once this is done the codes are then diagnosed to locate and repair the fault here.I have seen actuators on the heater box at fault as well as inside temp sensors fail and cause this here and having the codes checked will help pinpoint which is the cause here.

Also one other thing is make sure that the temp knob is at the coolest setting and either vent or floor/vent is selected for the ac to operate as the wrong settings on the controls can cause this here.

If these are all o.k. with the outside temp being warm enough and the outside temp sensor reading correctly and all settings correct then a code is set that needs diagnosed and repaired to correct this fault here.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

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