Alright everyone, here is the problem. The fan still only clicks on with the AC turned on, this is after changing every possible sensor and switch that would be involved. Its a 1992 TBI 305 that is baffling me. Is it still possible to be the RELAY, a cut wire somewhere, what anything any help anyone can provide would be awesome. :hail: Im stumped.

 

so is the car overheating? if the fans come on when the a\c is on then its not the relays. what is the temp it usualy gets to?

 

The car only overheats if i dont catch it and turn the ac on to activate the fan. The problem is the fan isnt turning on automatically like it should. ONLY with the AC does it turn on. So its not the relay? and i changed the fan switch, coolant tem sensor and temperature switch. NO CHANCE ITS THE RELAY? I dont want to screw anything else up while trying to fix this problem. Is it time to call it quites and have a mechanic look into this? Or do i take the time and check the wires for problems, anyone else have this problem. I can drive the car just have to remember to turn the ac on and cool the thing down. ANy more information is great folks, i apprciate it. 305TBI 92

 

Do you have dual or single fan? If dual, the ac turns on the secondary, not the primary fan, in which case it could be the relay for the primary that is bad. If it is single fan, then the fact that it comes on at all says that the relay is fine. Either way you could always wire in a manual switch into the circuit instead of using the ac to turn on the fan.

 

Alright so iv ruled out relay and just about all the sensors. The only thing i can think of is that the its a bad wire somewhere. Im thinking it the wire off of the Fan Switch thats bad. The thing i have to do is test it. Which consists of touching the wire off th FAN SWITCH to a good ground? If i do thiswith the key on, the fan should kick on correct? Even if its not at operating temperature? Any more information would be awesome guys.

 

If the ac turns the fan on, everything between the relay and the fan should be in working order. The wire to check is the dark green / white wire between the relay and the temp switch, and make sure the temp switch works. If it is stock, and the fan comes on with the ac, it has got to be one of those two things (the wire or the switch)

 

Alright i did the simple ground the green wire and guess what fan turned on. So my assumption is that the harness is a little worn out as well as the new sensor so, we ordered the JET replacement for 180 degrees. When i get done installing it ill let eveyone know how it goes. Thanks for all the help folks keep the information rolling in and before to long we will all be Fbody certified mechanics. lol.

 

what's up everyone!
I need help fellow GM enthusiasts!!! I bought an 86' IROC 305 TPI Vin # F that was a semi-basket case and the wiring harness was cut in a few places, the wires I have to IDENTIFY are in the TPI harness, they are: Green with white stripes and Tan with white stripes,they are located just before the TPS,IAC,MAF,coolant temp switch and cold start switch, the chiltons manual says they go to the fan relay, but guess what.....that was removed from the car as well, can anyone tell me how these two wires connect to the system? or can anyone send me a few pics of the harness showing me the relationship of these two wires to the relay? I also need to see what the wire harness looks like for the relay itself (wire colors and where the leads attach) any help would be greatly appreciated! I want to bring this Lady back to her former glory!
Thanks,
Ben Smith

 

I have a 85 TA with the same options as yours so it should be the same setup. What ill do is bust out the digital camara and take pics of the harness relay and the up by the fan. Give me a day and ill get it for you if youd like. Firebird9420@aol.com if you think you may need anything ese.

 

Snipe> I have the same car as you, so hopefully I can help some here. Unfortunately, when it comes to the fans and lights, I have rewired those circuits. The tan wire should be switched hot thru the ignition and the green wire is switched ground thru the ECM (controlled by the coolant temp switch).
This picture is from an aftermarket relay, but the idea is the same. Your green wire is #85, your tan wire is #86. #30 is a heavy red or orange wire that comes from the battery, and #87 is another heavy red or orange wire that runs to the plus(+) side of the fan, and the gnd(-) side of the fan is grounded to the chassis. The relay is mounted on the radiator support above/behind the battery,

 

i finally found the problem the first sensor tha t u ought from auto zone was defective and wasnt workin i ordered the jet fan switch from smmit racing that has a new connector and every thing now my fa works when its supposed to