Ok, I got my fans sorted out today for the most part so the car is drivable. I have a few tech questions though, for those who know.

I've done a lot of searching, that's how I found the part numbers for the different temperature switches, schematics, and how to papers from here to California. In the end, I printed out the schematics from my 88 Firebird service manual VIN F and just wired it that way. It works but.....

The primary fan comes on as soon as the engine is running and stays on all the time. This relay is controlled by the ECM according to the Firebird schematic, and it seems that it probably is since the fan doesn't run when the key is ON, just after the engine is running it immediately fires up and then does not shut off unless the engine is off. Cycling the key after shutting the engine off does not turn the fan on, but as soon as you start up its on again. I'm thinking CTS, but I don't have any datalogging software yet to see what the ECM sees. I'm searching the forums for that right now.

Next, I'd like to know what goes in the front of the intake right next to the CTS. A previous owner installed a manual temp gauge there and I'd like to take it out, but I'm not sure what goes there. I am thinking of putting the Grand National water temp sensor there to control the primary fan since the ECM seems to not be able to handle the job at the moment. For now I'm leaving it while I test everything else out, but when I'm done that gauge is leaving and I'm not sure if something is SUPPOSED to go there or just plug it.

Thanks for the help/opinions.

 

Just a quick mention.....When you start the car, the fan will come on everytime for about 20 seconds or so. This is normal. Even during a cold start.

If your A/C is on (I see you live in FL), that driver side fan will stay on all the time. Try starting and waiting a minute with a cold start with the A/C off.

 

The AC is inop at this time. The condenser is MIA, so there is no pressure in the system to set it off. Is it possible that maybe the dash controls are telling the ECM that the AC is on, or does it only work off of the pressure switch telling the ECM?

I honestly don't know. Thanks for letting me know about that cold start situation. That has me looking more closely now.

 

not to bring up a old thread, but this same problem has been with my 89 iroc also.
As soon as the engine is started the primary fan starts to run. Only way to cut it off is either turn the engine off or pull the relay. It doesnt do it with the key in the ON position just once the engine starts.
Wiring is all stock and not hacked anywhere. I have read and searched all over for pointers and this electrical stuff has me stumped.
The ecm does show a code 14 which is related to the CTS, but the CTS is new.

 

Anytime the ECM sets code 14, the ECM commands the fan to stay on constantly. You must fix the problem making code 14 to go on to the next step.

Bottom line, you have to run down the wires to the CTS and verify all the connections. If you replaced the sensor you should be able to rule that out, but aftermarket chinese stuff is not 100% dependable. New ones go bad or intermittently flake out just like old ones do.

My car had broken connections at the connector to the CTS. This is one of the many reasons that the ECM was flipping out and causing the fan to run constantly.

 

Well I would have bet the farm against it but turns out it was a bad sensor. The one for the fan just below the thermostat housing. I had changed it back when i first got this car. ( this has been almost a 4 year resto project) I think i got the sensor at carquest or somewhere. Anyhow i went this morning and picked up a AC Delco sensor, put it in and no SES light and fan stays off as it should lol.
So once again, even a new out of the box part can be bad.