Hi!
I have a small issue with my primary cooling fan.
The car is a Camaro 1988 with 305 TPI and TH700

My fan primary fan starts to run when I start my engine.
I have changed the fan relay, temprature sender ( the one in the fron of the manifold) but it still runs.
The green wire from the relay that goes to the ECU is fine and not damaged, and I cant see that anyone have done a mod or so to the fan wiring.
The ECU is set to 86 degree celcius as start value.
Have anyone some ideas where to look next.

Thanks

 

Is the fan switch for a/c set correct?

 

The primary fan is only triggered by the ECU.

The secondary fan have the high preassure sensor hocked up to the ac system, but the system is low on R134.
The temp switch for the secondary fan is broken and hooked up to a manual switch. It I jump the ac high preassure switch the secondary fan starts.
I dont think the primary fan will start with ac senders

 

So if c1 of the ecm is grounding the relay the ecm is faulty since it’s not commanded.

 

Okay. So you think it is time to change the ECU itself.
is it a common problem?

 

I’m pretty sure the fan switch in the tune would command the primary. But if all that’s fine and the ecm is grounded the relay not commanded then the ecm is bad. Or it has a cold solder joint.i had a customer recently firmly press down on the memcal flexing the pcb it stopped the fan request. He reflowed the ecm joints but no success.

 

Okay. Thanks.
I’ll better look for a replacement ECU then.
I guess there are all the same 1988 tpi models, so I just move over the memcal

 

1227165 or superseded number, yes just swap the memcal

 

Thanks for the ECU number.
I have a local dealer in sweden that might have a ecu on stock, I will try that out as a next step.

cheers

 

Could ask this Facebook group the 165 was used 86-89 tpi

 

thanks.
Cool that you found my post on that side

 

Does the fan continue to run if you disconnect the AC high pressure switch? If you remove the relay?

 

The fan runs when i remove the highpreassure switch from the ac line.
When i remove the relay, the fan stops.

 

And also, the green/white cable at the relay socket that goes to the ecu are only grounded when the car runs. When stoped it is not grounded, so maby the ecu works

 

Have you swapped the relay for a known good one? I've had them stick closed

 

iirc it’s the same as the fp relay or blower relay.

 

yes, i have swaped them and it is still the same.

 

Did you check the wires going to the cooling fan relay connector? Mine were all deteriorated. I added some electrical tape and found that the fan then worked properly as the wire insulation had decayed and was grounding out the wires

 

I bought a hose adapter with a 95 degree switch and connected it to the fan relay. All good and works fine. I will see if I can find a new ecu in the future