Electric Radiator Fan will only work with the A/C on

[stevethecat]

I recently purchased a 2003 V6 LS and the electric fan wouldn't work at all. After replacing it again with a used one off of a V8 car the fan works again. I did have to swap the plug on the fan to match the dual plugs my car uses. I used the plugs off of a Dorman oem replacement fan that ended up being a dud.
Its been hot lately so ive had the A/C on and its been cooling fine. The car with cool down at a stop and i haven't seen the temps rise above 208 since. But I drove it with the A/C off the other day and the temperatures kept running hot and it would keep heating up at a stop and I shut it down at 220 degrees before it overheated. If i turn the A/C on the fan kicks in and the car cools fine but even at extreme temps the car wont turn the fan on without the A/C running.
Im at a loss does anybody have a suggestion

 

[stevethecat]

Would this be a computer issue or a sensor. I know the car reads temps from a set of sensors not in the coolant lines.
Also my temp readings are from a Bluetooth OBD2 plug and the tourqe app on my phone. So im not sure how accurate the water temps are.

 

[Blueberryyum02]

My first thought would be to check the relays, second I would check to see if it's wired to the A/C clutch and the coolant temp.

Cause judging by what your explaining, it was hooked up to run only wit the ac on. Which means the previous owner left the system running constantly.

And you might need to replace or add a temp sensor on the radiator itself to trigger it on when the a/c is off.

 

[stevethecat]

Thanks ill get started on that right away. How do i test the relays?

 

[joegr]

There are no relays related to the cooling fan on the LS.
(The gen II fan has an electronic speed controller built-in. The PCM sends it a PWM signal indicating how fast it wants it to go. If the signal line gets disconnected or shorted, the fan failsafes to full speed operation while the key is on.)


I wonder if the problem is in the programming of the PCM. Getting it "flashed" at a dealer might resolve this (no promises on that). The PCM has to actively tell the fan not to run. Of course, it may be doing so due to a bad temperature sensor, but I would think that would trigger some fault codes (if it is thinking that the engine never gets to temperature).

 

[MIdsm]

I wouldn't be surprised if your fan didn't come on till at least 225. I was towing last year and the temps were over 220 according to the obd2 reader. I let the car cool down and took it nice and easy. Temps would rise between 225 to 228 and then drop to 219. That evening I checked here and found out that the high temps are normal (at least for v8s). According to the online manual (V8) the thermostat should start opening at 219 so the temps will go over that. My temp needle was still at the mid mark at 225 but it doesn't show the actual water temp. Also, the manufacturers keep rising coolant pressures and temps in order to get more complete combustion - more power and better fuel mileage; at least with naturally aspirated cars. Good luck.

 

[Telco]

It is possible for a temp sending unit to break in a way that it will register up to a point, then no further. It's rare, but it happens. Temp sending units are cheap enough to try throwing one at the problem to see if it solves it. However...

I recently purchased a 2003 V6 LS and the electric fan wouldn't work at all. After replacing it again with a used one off of a V8 car the fan works again.

(The gen II fan has an electronic speed controller built-in. The PCM sends it a PWM signal indicating how fast it wants it to go. If the signal line gets disconnected or shorted, the fan failsafes to full speed operation while the key is on.)

Connection, perhaps?