i searched many posts and found some info but not enough. my prim. fan consantly runs with ignition on. relays are good for sure. trying to locate themostatic switch that EVERYONE says is on the pass. side head which i have no sensors or switches on any of the pass. side heads of my camaros. the only thing i found is in the BLOCK above the starter. is that what im looking for? also if the switch is not my problem, how can i figure why they run constantly? fan does not work when i unplug the fuse or relays.

 

i beleive that mine was on the intake. two wires went to it. might check there next to the thermostat housing.

 

I'm having the same problem on my '88. I turn the ignition on and after a minute or two, the primary (left) fan will start to run. I know the car is not hot because it hasnt run in 5 years ( I tried to start it today after getting the motor back together) ALL cooling system relays and all the switches in both the heads and intake are new GM parts, except for the new Jet fan switch in the pass head.

any help would be greatly appreciated.

 

Seems like this is the same problem I'm having.
1988 IROC-Z 305 TPI Automatic
Change prom for a Street Performance Chip
Changed thermostat to 160 with new 160 fan switch
Now I have primary fan running, but not when ignition is first turned on (cold) only when engine is started does it run constantly.
Is there a test procedure to check this problem? Manual refers to hot running and fan not working procedure.
Not sure if this is part of problem, Engine light comes on after engine has run and restarted indicating MAF problem. This doesn't always happen it's intermitent, I can count to 20 sometime and restart without light comming on. This has happened since new.

 

The one on the block (ONE WIRE = TEMP SWITCH)The one on the block, take it out and if coolant poors on to your head then ya it's the TEMP SWITCH> That's what happened to me! LOL! and the obvious one on top/Intake (TWO WIRES = COOLANT SENSOR).....

 

i had this problem ever since i removed my AC, then i realized theres a sensor in the AC lines that needs to be kept in place. once i reinstalled it, everything worked the way it should have.

 

You have a switch (it's not a sensor) on the pass side for sure, I have a 87 5.7 too. It's right next to the dipstick. it's a 1 blade switch, it grounds the wire to gnd @ switching temp

The fan is running all the time because there is a short to ground on the switch side, either by a disconnected wire lying against a metal part or by a burnt or bare wire touching something, if you have headers this is very common.

With your description of a sensor in the block above the starter, that must be it. it's however in the head not the block but it's right above the starter area. There is no port in the block above the starter. The only one is for the knock sensor, it's above the pan rail dead smack in the middle. The other threaded hole is for the starter brace (if so equipped)

It could also be the AC switch that turns the fan on. If you short out the pressure switch in the large hard line, the fan will start running regardless of temperature. If you disconnect the hi pressure ac switch, which is located in the small hard line the fan will also start running.

Check this pic, see the sensor between cyl. # 6 & 8? That's it. This is a later style weatherpack one yours should have a connector style like the knock sensor has (if original)