Radiator Fan Constantly Running

[sectorz]

I guess the title pretty much sums up my problem...any ideas guys and gals?

It's starting to get colder, and my heater barely pumps any heat. I'm thinking it might be related to the problem above.

Thanks in advance!

[Tercel GTS]

Could be a stuck fan relay, bad sensor or wired like that by a shadetree.

[sectorz]

Thanks for the help!

Is there any way to test the relay?

My engine temp guage appears to be behaving normally so I think I'd elect to check the relay first.

Where is it located? I have a '95 tercel DX

Cheers!

[Tercel GTS]

I'd begin by locating the temp sensor, most likely near the thermostat or water outlet(near the hoses). Unplug it and see if the fan stops. If not then move on to the relay, most likely in underhood fusebox. If unplugging that stops the fan then you'll have to get a wiring schematic and figure out what wires should be powered/grounded and when. Good luck, take pics and tell us what you find.

[sectorz]

I should be able to find some time to look into this over the weekend..

I'll report back!

Thanks again for all your help.

Cheers

[sectorz]

Well, since I've been so busy, I yanked out the relay and sure enough, the fan stopped.

I think I'll try just replacing the relay.

If the temp sensor was failing, the fan wouldn't come on at all, would it?

[Tercel GTS]

The temp sensor could be stuck 'on' also. That's the next test, unplug the sensor. I've heard our sensors run on an open circuit, so when you unplug the sensor with the relay plugged up make sure you jump the 2 wires together that go to the sensor.
If nothing changes with the sensor tests then try replacing the relay.
A few tests = no money wasted on parts not needed.

[Donald]

Originally Posted by Tercel GTS

I'd begin by locating the temp sensor, most likely near the thermostat or water outlet(near the hoses). Unplug it and see if the fan stops.

No, no, no. The system is "fail safe to run". If the thermo switch wire or the wire to the A/C pressure switch comes loose or breaks or either of these switches fails the fan will run constantly. I had this problem when I did my engine swap because I hadn't hooked up the A/C wiring. I solved my problem by putting a jumper wire to bypass the A/C pressure switch.

Test the thermo switch first by disconnecting the wire and putting it to ground. If the fan stops, then you know that it is that switch. If it doesn't then find (up under the dash) and ground the A/C pressure switch. If that doecn't do it then do a continuity check on the respective switch wires. You will need a manual, and be able to read a wiring diagram.

Good luck.

[Tercel GTS]

^ty for clearing that up.

[Donald]

No Prob.