1997 Chevrolet Lumina Engine Cooling Fan/Overheating Issue

Tiny
KIRBYGRAYCA
  • MEMBER
  • 1997 CHEVROLET LUMINA
  • 3.1L
  • V6
  • 2WD
  • AUTOMATIC
  • 124,000 MILES
I have my girlfriends grandfathers 1997 Chevy Lumina LS that she got after he passed away last year that I'm having overheating/engine cooling fan issues with and I am stumped. This car sat in a garage for pretty much the past 10 years, so I immediately thought that the GM orange coolant had clogged the radiator, so the very first thing I did was replace the radiator. Long story short, I have since replaced the thermostat as well as the coolant temperature sensor and the cooling fans still won't respond. I disconnected the cooling sensor and completed the circuit with a paper clip, and then the fans came on, however they won't when it's connected to the sensor in the engine. I also, by trial and error, put a new relay in each of the 4 pronged relays in the boxes under the hood and tried turning on the AC to see if THAT would get the fans to engage, and they didn't. Am I missing something obvious or is this going to require a mechanic because I'm at the limit of what I can do at my home. ANY help would be greatly appreciated. Thank you.
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Friday, December 4th, 2015 AT 12:57 PM

3 Replies

Tiny
HMAC300
  • EXPERT
Check fuses pointed out in pic and fan relays there are 3 one is not pictured due to space everything is under the hood in that fuse box and should be marked. The pcm controls the fans. If relays are good and fuses then have a pro look at it. It may be a short in wiring from pcm to fuse box or wiggle relays and see if it starts if it does get some dielectric grease and put on prongs of all 3 relays.
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Friday, December 4th, 2015 AT 1:33 PM
Tiny
KIRBYGRAYCA
  • MEMBER
Ok. What is the PCM? Also, I've read on this site that the temperature gauge operates off of a separate sensor. Is that true?
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Friday, December 11th, 2015 AT 11:56 AM
Tiny
HMAC300
  • EXPERT
The pcm is the powertrain control module which controls the fan. The one is ect or engine coolant temp sensor. The power goes from the pcm to cooling fan relays if your fan works with a/c on relay 2 is good the other two are used for speeds one for low speed the other for higher speed. You can check the ect with an ohm meter to see if it is good or not at about 70 degrees it should have around 3520 ohms and at 212 which will be when engine is warm it should be around 177 ohms. If you get these readings then the ect is ok then it's one of the fore mentioned problems. There is no separate sensor for gauge that would be a switch which you do not have.
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Friday, December 11th, 2015 AT 12:07 PM

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