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ASEMaster35yrs, Chevy Technician
Category: Chevy
Satisfied Customers: 2095
Experience:  ASE Certified since 1972,Master Auto tech,Heavy Truck Tech ,chev dealer tech
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Chevrolet Corvette: 1993 Corvette Coupe - LT1 Engine. Cooling

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1993 Corvette Coupe - LT1 Engine. Cooling fans do not come on, even when AC is turned on. Is this the ECT Sensor, or the Cooling Fan Temperature Sensor, or both?? What is best course of action?

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with the engine running and you unplug the 2 wire coolant temp sensor (CTS)will the fan turn on ?



Customer: replied 3 years ago.

Have not tried that yet. If I unplug and fan turns ON, then what?? If fan does NOT come on, then what?

if you unplug it and the fan runs either the connector you just unplugged is bad or more than likely the sensor is bad

if it will not run then we need to do some tests on the coolant relay with a multi meter or test light

Customer: replied 3 years ago.

Ok will try this when I get home. How do I reply from different computer?

just right back through this post

you can save the post link in your email and then get back in through that way

Customer: replied 3 years ago.

Got it! Will follow up when I get home. Thanks!

Customer: replied 3 years ago.

Gary....good news. I started car, and unpugged the aforementioned sensor. The fans kicked on immediately. I have a new sensor here at the house. What is involved in changing it out? Draining coolant, etc. Or can I just change it out. Car has been cold for 4 days (other than the 30 seconds I ran it to perform this test). Thanks....Tim

Customer: replied 3 years ago.
Relist: Answer came too late.

Hi, glad to be of help. AC and radiator cooling fan circuits are two separate circuits. If unplugging the ECT sensor and fans come on, all that means is you have a good ground circuit for both radiator & AC cooling fan circuits. You may have two problems. I don't know. The AC fan will not come on unless you have compressor clutch request at PCM. The cooling fan will not come on full until ECT reaches 225-230F. If you disconnect ECT both fans will come on full. The first thing I would do is first check fuses & swap out or replace the relays. Check with scanner for AC request. Check AC pressure readings. If you have AC request, AC fan should come on automatically. If AC pressure reading is low there will not be an AC request since low pressure switch will terminate request. I would however replace coolant sensor since it is cheap and easy to replace. A bad thermostat can cause the ECT sensor not to engage the fans so that is another item I would replace just for preventative maintenance. These are two separate circuits and must be diagnosed separately.

Cooling fan wiring

ASEMaster35yrs, Chevy Technician
Category: Chevy
Satisfied Customers: 2095
Experience: ASE Certified since 1972,Master Auto tech,Heavy Truck Tech ,chev dealer tech
ASEMaster35yrs and other Chevy Specialists are ready to help you

im sorry for the wait

to change that sensor with it cold just change it out you might loose a tiny bit of coolant so just make sure your radiator is topped just unplug it remove it install new one

keep in mind these are pipe threads so do NOT try to tighten it in flush just snug then turn it a pinch more and leave it alone

Customer: replied 3 years ago.

No worries, was hoping to do it tonight, but I have a buddy coming tomorrow. We'll tackle it then. I have all three parts already (ECT sensor, Cooling Fan Temp switch, and Thermostat). Will change out tomorrow in driveway and follow up.

no problem

let me know how it goes

Customer: replied 3 years ago.

Went well. Drained the coolant first, changed sensor, inspected coolant, refilled. Car runs great, fan comes on at exactly 228 F. Thanks for the help, I appreciate it!!

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