86 v6 overheating with aftermarket fan

[Mikevs3]

I own an 86 fiero v6 with a/c and I'm having issues with overheating. I have an aftermarket electric fan and I know it works because whenever I turn my a/c on it turns the fan on aswell, but the fan doesn't turn on when the engine gets hot therefore causing overheating. I have replaced my fuse and the relay but that did not help. I do not know what to do next, what do you think the issue is?

[The Dark Side of Will]

Got DVM?

Backprobe the ECM pin to see if the ECM is turning the fan on. If the A/C turns the fan on, then everything else is tested.

Do you have a scan tool to look at what temp the ECM thinks the car is running?

Do you only have overheating problems when the car's sitting still?

[Shaun41178(2)]

Might be as simple as a bad fan temp sensor which is located in the lower intake manifold by the thermostat. We need more info though.

Assuming your coolant temp gauge is accurate, what temp is it getting up to? Will it actually get into the red?

You have enough foolant in the system and it was properly bled correct?

[Mikevs3]

I'm going to try and get a new sensor today, and my coolant was properly bled before if overheated and now it is running low. The temp gauge goes all the way into red when it overheats, but it's only ever overheated when it is parked not moving.

[Mikevs3]

Also I'm not very mechanically inclined so I do not know what a dvm is or how to back probe

[Series8217]

DVM stands for digital volt meter. Like one of these: http://www.northerntool.com/shop/tools/ ... Qgod5Q4ASg

Backprobing is simply sticking the probe into the back of the connector while it's plugged in.

It sounds like a faulty temp sensor or problem with the ECM wiring. It would be easy to diagnose with a volt meter, because you could trace the circuit and see what part isn't functioning.

[Mikevs3]

I don't have a dvm so should I swing by a parts store and pick up a new coolant temp sensor?

[Series8217]

I hate to suggest throwing parts at a problem without a thorough diagnosis. A DVM is probably even cheaper than a new sensor and you will get a lot of use out of it.

If you put a new coolant temp sensor in and the problem isn't fixed, you will need a DVM to diagnose further.

[The Dark Side of Will]

I'll never suggest to throw parts at a problem The DVM will be cheaper in the long run.

[Series8217]

Backprobe the ECM pin to see if the ECM is turning the fan on. If the A/C turns the fan on, then everything else is tested.

I've never owned a Fiero with a 2.8, but I saw there's a listing for a fan switch on Fiero Store. Does that switch work in parallel with the ECM?

[jelly2m81]

Backprobe the ECM pin to see if the ECM is turning the fan on. If the A/C turns the fan on, then everything else is tested.

I've never owned a Fiero with a 2.8, but I saw there's a listing for a fan switch on Fiero Store. Does that switch work in parallel with the ECM?

The Fiero fan switch is the ground path for the fan relay . It is not tied the the ECM in anyway.

Easy and fast way to diagnose the fan switch and everything forward to the fan is to turn the ignition on, remove the fan switch connector and ground it, if the switch is at fault and the rest is good the radiator fan will run.

The fan switch connector is at the front of the engine closer to bank 2. Single wire squeeze connector with a green / white tracer wire.