I have a 1988 Firebird with a 305 TBI.

It has a single electric rad fan. The fan will not turn on, no matter how hot the engine gets.

I know the fan works because I pulled the single sensor wire off the temp sensor in the passengers side head and grounded it. The fan came on and stayed on. I replaced the sensor thinking it was the problem. I reconnected the wire and ran the engine to the point of overheating but the fan still wouldn't turn on.

What else is on the circuit that controls the fan?
Anyone have any idea what else could be the problem? Any help would be greatly appreciated.

 

If you have A/C, just switch the A/C on because the fan automatically comes on with the A/C. It still might be a bad fan switch.

 

I don't have A/C...

Anyway to test the temp sensor? I agree I could have bought a dud but I'd like to know if this is the problem before I go thru the hassle of changing another one.

 

Here's a picture of the Jet Fan Switch I bought from Summit. It was $38.69 from Summit part #JET-60600. Works fine.

 

Anyone else know anything about the fan circuit? I talked to the dealer in my area but they want me to bring it in -big bucks I don't have. I really need to fix this myself if at all possible...

Were is the relay located? Could it be bad? How do I test it and the block sensor to see if one is bad?

 

Just a thought, Did you put any kind of sealant on the sensor before you installed it that might be keeping the sensor from being grounded right? It seems if the sensor isn't getting a good ground it wouldnt work. Other than that it would have to be a bad sensor if the fan comes on when wire is grounded..

 

i think i shold make these diagrams and pictures sticky.....

 

I had the same problem take off the teflon tape on the sensor it prevents in from grounding. or install the $10 kit from kragen. it has a new sensor and thing with a dial ( sorry can't think of what they call it) that you can adjust the temp. EZ to install.

 

If he had A/C he would have 2 fans but he only has one

 

I'm still hung up on your first post. You said that if you pull the wire off the sensor and ground it the fan kicks on and works. If that is still the case, the rest of the wiring/circuits must be working correctly--the temp sensor isn't gounding at the proper temp(probably around 220) or the engine isn't at that temp yet. Maybe the temp guage isn't working accurately and you aren't overheating yet.