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Ask Tool Hut Your Own Question
Tool Hut
Tool Hut, ASE Certified Technician
Category: Chevy
Satisfied Customers: 515
Experience:  Owner of a mobile diagnostics company assisting auto technicians with difficult vehicles
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Cooling fan does not work when air is on or when temp is up

Customer Question

cooling fan does not work when air is on or when temp is up fan does work when connected direct to 12v 2005 chevy cobalt 2.2 all fuses good and relays replaced
Submitted: 1 year ago.
Category: Chevy
Expert:  Tool Hut replied 1 year ago.

Hi, My Name is ***** ***** for posting your question to just answer. I am a ASE Certified Master Auto Technician with 20 years experience. I am confident we can resolve your problem together.Please remember I don't know your skill level. I can't see, smell, hear, or touch the vehicle. It may take a few back and forth replies to get to a satisfactory resolution.I also try to give all of the information you may need expecting a positive rating.

DO you have a test light? Can you check the cooling fan relay for power? See schematic attached

Customer: replied 1 year ago.
i have power on 30 and 85.
Expert:  Tool Hut replied 1 year ago.

Do you have ground at 86? Can you cross 30 and 87 and make fan work?

Customer: replied 1 year ago.
when i cross 30 and 87 fan does not work
Customer: replied 1 year ago.
i don't seem to have ground at 86
Expert:  Tool Hut replied 1 year ago.

The ECM controls ground. Have you checked both relays?

Customer: replied 1 year ago.
i have replaced both relays and checked both to try to start fan.. i also light my test light off of all three wires going to the fan? should that be?
Expert:  Tool Hut replied 1 year ago.

The black wire should be ground. and it is constant at the fan

Customer: replied 1 year ago.
should all wires light the light when i ground it to the frame
Expert:  Tool Hut replied 1 year ago.

2 should 1 should not

Customer: replied 1 year ago.
ok well they all do.including the black
Customer: replied 1 year ago.
with fan unplugged black lights light and the other two do not with fan plugged in they all light light.
Customer: replied 1 year ago.
thanks for your help. I'm sure your busy. no problem I guess we'll just take it to a garage thanks anyhow.. Brian
Customer: replied 1 year ago.
we got no father than where we were.
Expert:  Tool Hut replied 1 year ago.

The black wire should be grounded near the bottom of the radiator support. check it for a ground.