Coolant fans behavior 4th Gen Camaro -RESOLVED
 

My turbo Z28, using a 5.3, has been amazing these last 3 years. Most impressive to me is that the coolant temp at fully warm leaves the gauge halfway between the first two marks. But 2 days ago, I noticed it crept up to just under the 1/4 mark unless I was cruising. Past experience with a failed fan (and these are the Derailes) made me suspect a fan had failed. So I pulled up to the shop, leaving her running, popped the hood and sure enough, one fan (fan 2) was not spinning. Fan 1 was getting the full 12v and was singing.

I went back into the cab of the car, opened up my HPTuners software, connected the logger/scanner and clicked on special functions. Navigating to the 'Fans' tab, I clicked the button on Fan 2 (ON button), then got out and looked at the fans. To my relief, both fans were turning fine. I turned the key off to kill the engine, disconnected my HPTuners, let the car cool awhile, then went and started the engine. Curiously (to me anyway), when the engine warms up enough to turn on the fans, both start up fine, with what I've read is 6volts(so half speed). After it reaches a certain temperature, 12v is applied. But on my setup now, only Fan1 gets 12v while fan 2 stops spinning altogether.

Is that normal? I've never had to analyze the fans behavior before.

I've made sure the coolant in the radiator and overflow bottle are perfect.

After putting some jumper wires in the slots of two of the relays to makes sure both fans could be turned on. I went back to my old Haynes manual and looked that 'coolant fans' section. Hmm... only two fans but 3 relays. Two of the 3 relays came with the car when I bought it brand new in Nov of 95. So I figured, "what the heck?" and replaced all 3 with brand new relays. Viola! Coolant temp at fully hot is back to being between the first mark and the first quarter mark. I opened the hood while she was running at full hot and both fans were doing their job.