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AMEDEE
AMEDEE, CHEVY TECHNICIAN
Category: Chevy
Satisfied Customers: 26071
Experience:  ASE certified tech ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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1998 3.1 Cooling fans don't turn on when ac is switched on.

Customer Question

1998 Monte Carlo 3.1
Cooling fans don't turn on when ac is switched on. Compressor turns on, but not the fans.
The fans will turn on when engine temp gets high enough.
Submitted: 10 months ago.
Category: Chevy
Expert:  AMEDEE replied 10 months ago.

Hello and welcome!

My name isCustomerand I can assist you with your question.

Expert:  AMEDEE replied 10 months ago.

Can I start by getting your VIN and the codes in the computer? Thank you!

Customer: replied 10 months ago.
Check engine light is not on. I will get the vin and back in a minute
Customer: replied 10 months ago.
2G1WW12MOW9278872
Expert:  AMEDEE replied 10 months ago.

Sounds good

Expert:  AMEDEE replied 10 months ago.

Thank you for that information. One minute

Expert:  AMEDEE replied 10 months ago.

Ok, sorry for the delay!

Expert:  AMEDEE replied 10 months ago.

The first thing you are going to want to do is check the fuses and cooling fan relays and check to ensure that the cooling fans receive power when the relays are activated by the PCM.

Expert:  AMEDEE replied 10 months ago.

If the powers to the relays and fuses check out good, then chances are the PCM is not grounding or activating the cooling fan relays. This is either due to a bad engine coolant temp sensor or a cooling system issue (such as low coolant, air pocket in the system, bad radiator cap or blown head gasket). Sometimes the PCM itself may go bad causing this issue as well but that would be a last resort.

Expert:  AMEDEE replied 10 months ago.

Have you checked the relays and for power to the fan relays? Do you need a wiring diagram for this circuit?

Customer: replied 10 months ago.
a wiring diagram would be helpful.
Does the signal for "on ac" go through the temp sensor before the relay?
Expert:  AMEDEE replied 10 months ago.

It goes through the PCM.. which should allow the cooling fans to run (or at least one)

Expert:  AMEDEE replied 10 months ago.
Customer: replied 10 months ago.
Regardless of engine temp, correct?
Expert:  AMEDEE replied 10 months ago.

Thats correct!

Expert:  AMEDEE replied 10 months ago.

If this is the case, I suspect a power supply issue to the cooling fans or relays or simply a bad PCM.

I am glad I can help!

It has been a pleasure working with you. Please dont forget to honor your good faith deposit by rating my answer as "Excellent Service" for assisting you today.

Please let me know if you have any further questions.

Expert:  AMEDEE replied 10 months ago.

Hello! It'sCustomerfrom just answer.

I am just checking in to see if you need any further assistance?

Let me know!