Hey guys,

My engine started to overheat when in traffic or running under 30mph. I changed the theromostat and still same thing. Lifted hood when running hot and elec fan isnt working. Where do i diagnose first? Fan motor (fan turns by hand freely) or is there a sensor that tells the fan to turn on, if so, where is it located and does the local auto parts store carry one? It is a 305 TBI engine. Thanks, MIKE.

I also have a 92 rs with a 305. I had the same problem with the fan, and a replace of the thermostat fixed it. its suppose to come on at 225 which is straight up in the middle on the temp gauge. I ruined an engine because of a faulty fan, so keep in mind the radiator itself wont keep the car cool. A toggle switch would be a good way to insure the fan is on. hope this helps

The TFS (thermal fan switch) is located in the passenger side cylinder head between the third and fourth spark plugs. They should be readily available at the local auto parts.
If the fan is good it will run when the A/C is on, there is also a relay for it's operation. The TFS or the A/C grounds the realy to turn on the fan, so if iti runs with the A/C is on the relay is good.

Jeff

The first test would be to check for 12 volts and a ground at the fan, after checking fuses of course. If you have A/C it should come on when the A/C is on and the head pressure comes up. If it comes on then you probably have a bad fan switch. You can ground the wire that plugs onto the fan switch and it should run also.

The first test would be to check for 12 volts and a ground at the fan, after checking fuses of course. If you have A/C it should come on when the A/C is on and the head pressure comes up. If it comes on then you probably have a bad fan switch. You can ground the wire that plugs onto the fan switch and it should run also.

The fan doesnt come on at all, reguardless of the A/C being on or the engine over 220 deg. I will check for power, if power is going to the fan then the fan is bad correct? If not, would it be the radiator temp switch in the head or a reay of some sort?

If you have 12 volts on one wire and a ground on the other, the fan motor is bad. If you don't have 12 volts, check the fuse and the relay.

Apply power and ground directly to the fan motor and see if it runs. Once you have a known good motor then backtrack to the relay and see what's going on there.

Jeff