Yeah this year for the first time that happened. It was a typical +100°f July day in Texas I'd had the A/C running also. The Kenlowe fans came on AFTER I'd turned the truck off and ran for about 5 minutes to cool it off. I had actually turned the A/C off before I turned off the truck and heard them stop when I did. They came on again about ~10 secs after the engine was shut off.

 

I have the same problem and am trying to find the auxiliary fan sensor. I get all kinds of help except what I need. I found a sensor on the left side of the block above a freeze plug and the engine mount. This sensor goes into engine water which should be the hottest. I think this is the sensor I need to change. I just want confirmation that this is a fan heat sensor. I cannot understand why all my source printed and on-line fail to discuss the location of this fan sensor.

 

I'm pretty sure that's the knock sensors.

Coolant sensors should both be on top. At least on the d1

Either way.. Your engine should not overheat, and the aux fans are not there to keep it from getting there idling. If your engine is overheating with The a/c on but not off it IS the fan clutch.

 

Coolant temp sensor for the D2 is a single unit, between the alternator and AC compressor, on top. It signals the ECU, the ECU drives fueling, dash gauge, electric fan relay, and other things from this single sensor. A scanner or ultra gauge can show you the digital temp the ECU is monitoring at any time.

Electric fans in a D1 come on with AC, and at other times. On a D2 they follow a slightly different set of rules:


If electric fan never comes on that is a problem. If electric fan blades don't spin freely, motor is siezed or almost. If keep blowing fuse the motor is siezing up.

If viscous fan clutch allows main fan to spin more than 1 revolution when hot or cold, when spun by hand and released, then it has lost internal fluid and needs to be replaced. Should feel like peanut butter inside, not penetrating oil.

Dash gauge is designed to be innacurate to avoid widespread panic. The engineer who designed it (Dr Goofus Bastid) has a brother (Robin Bastid) in the head gasket business. Anything above 50% is suspect. On a D2 it is a digital reading running an analog pointer (cool, OK, toast). On a D1, not much better.