cooling fans won't run on high

**occamaroz** · 01-10-2008, 05:33 PM

I've had them programmed for a while with a predator to run cooler and all the sudden they wont run on high, only low. What should I check?

**SSTODD** · 01-11-2008, 07:56 AM

There is no HI/LO, only on or off. One fan was set to turn on first and then if the temp. was not dropping the second would turn on at it's set point. I would verify your program settings and then maybe verify each fan.

**2001NBMZ28** · 01-11-2008, 08:15 AM

On mine both fans operate simultaneously on either low or high speed at the on/off temps programmed.

Responded to your other post in stereo/electronics because I saw that one first.

**Bobby97SS** · 01-11-2008, 03:14 PM

The cooling fans work off of three relays configured to supply power to the fans in series for low speed (6 v. each) and in paralell for high (12 v.) This is how all the LTand LS powered f bodies and vettes that Ive seen work. I think the OBD1 LT motors were wired different. If you have 3 fan relays then thats how yours works too. Relay failure could cause the loss of one or both fans and one fan motor failing could cause the loss of both on low.