rwstegne

So, having a problem with my 1989 iroc heating up in traffic. It is a true iroc with dual stock electric fans, but some modified it so the drive side fan turns on as soon as the engine is running. The second fan only kicks on when the AC is turned on. The car does have a custom chip from a local performance shop and it is set for 185F.

Shouldn’t the second fan kick on once the coolant temperature sensor hits the temp programmed in the ECM?

• I have tested the relay by grounding the green wire, but it is obviously good since the AC kicks the fan on.
• Fan is good
• I check that the coolant temperature sensor is getting voltage when the car is running.
• I have replaced the coolant temperature sensor twice

What am I missing?

How do I figure out if the ECM is sending the voltage out to the relay? Where could it be broken?

abray1

Its working just not at the temp that is good for you. Ground the green wire through a switch in the dash and turn it on when you need it. I have several switches in the ashtray in my car so I can close the lid and hid (cover) them.

Ozz1967

iTrader: (4)

The first fan, turns on with the ECM, the second fan turns on with the fan sensor in the passenger side of the block. Since it's coming on with the AC, as it's supposed to, that means the relay is working. You have two sensors in the block. One on the drivers side, this is the engine temp sensor that feeds your temp gauge in the car. The second is the fan switch, located below the #4 cylinder on the passenger side. There is one wire going to it. There is aother sensor much further down toward the bottom, this is knock sensor. I would guess that either your sensor in the block is bad, or the wire is bad.

b_the_j

at what speeds are you talking?

Ozz1967

iTrader: (4)

He said in traffic, so I"m assuming under 35mph. If it's over 35, then the second fan not coming on is only part of the problem.

Also, how hot is it getting in traffic? You didn't mention.

rwstegne

Thanks guys! Finally figured it out. I trouble shooted it to a bad fan switch. Replaced the stock fan switch with a hypertech and it solved the issue. Obviously, the car was heating up in traffic because the second fans was not kicking on. I hope there are no other issues contributing to it!!!! Just have to keep an eye on it.

Reid Fleming

iTrader: (2)

Fan on/off temps are in my sig.

Ozz1967

iTrader: (4)

Glad to have been able to help!