Got a 92 Formula firebird, 5.7L 350. Got it 2 years ago with 130k original miles, and it was running great. Recently started overheating and problems seem to be related to the second fan not coming on. My fan has a 2 fan setup. The primary, from what I gather, is connected to the computer, which switches it on based on temp. The secondary is supposed to come on when either the engine temp reaches a certain level (cooling fan switch) or if the AC is turned on.


The first fan works. When I let the car idle in the parking lot, it heats up to around the midway point on the temp guage (220 I think?, not sure bc the car isn't infront of me. exactly halfway on the guage). Then the first fan (drivers side) kicks on. So that mech seems to be ok. But the temp keeps going up. As it climbs, I expect the second fan to turn on, but it doesn't. If I turn on the AC, the second fan DOES NOT come on.


Today I decided to check the relays. I find 3 relays under the hood on the drivers side, next to the dash. The outermost relay, closest to the side of the car, seems to be the relay for the first fan. if I jump the connection, the first fan goes on. The second relay (in the middle) seems to be for the AC. When I jump this connection, I hear a sound that might be the compressor -- am I right?? When I do this jumping fan #2 DOES NOT turn on. The third relay (closest to the center of the car) I have not tested. I'm assuming this is for the fuel injection system--am I correct?


At this point, I'm thinking that the problem may not be in the relays. Possibly in the second fan, itself. So, I spent the afternoon taking the second fan out, and swapping the fan motor with a new one from autozone. I put the fan back in, wired it up, but it does not come on, even when I force the AC (by jumping the middle/2nd relay).


What's the next step? have I isolated the problem to something wrong with cables? Is there a fuse or something between the relay and 2nd fan? Thank you.

 

Find the switch that turns on the second fan . Take the wire off it. Attach it to ground. Turn car on. The second fan is mechanically operated. Path to ground through switch completes circuit. If fan comes on switch is bad.

 

http://austinthirdgen.org/mkportal/m...ine_wiring.gif

 

Thanks IROCZ,

By "switch" are you referring to the cooling fans witch attaced to the passenger-side head (around cylinder 6/8)? Is this the one to try grounding?

 

Yes, ground that wire and they should kick on. The wiring diagram I posted shows the power and grounds. You can use that to see where you have power or where you don't. Its really a simple setup.

 

Thanks TTOP,

will ground er tonite and let you know if it works.

 

Make sure the key is in the run position before you try it.

 

I tried looking for this wire today and couldn't find it. A few questions
1.) is it possible to find this switch from the top, or do I need to lift the car to get access to it?
2.) is it going to be on the passengers between 6/8 on the 5.7 firebird 1992 350, or could it be in a different position on this car?

Thanks,

 

If you cannot find it, there's a good chance it fell off or melted off. Sometimes the plastic shroud wont be there and have cracked off or melted off. Is the switch there in the head at least?