Overheating on idle, fan not working, 90 celica ST

[bafoon]

I have a 1.6L, 4cyl, 1990 Celica with the 4AFE.

The car wasn't getting up to temp (though the fan was always running!), so I changed the thermostat. Now the car gets up to temp but the fan doesn't turn on. It overheats if left to idle for 5-10 mins without having the heat on. The heat is hot, as it should be.

The car does not overheat while moving or if the heat is on while idling. I do not believe there is any air left in the system, and there is no apparent leaking except for when the car gets too warm and coolant begins to overflow from the overflow reservoir.

I changed the coolant temp sensor - still no fan. The water pump is working fine. I began reading forums and a lot of people discuss a cooling fan switch usually located on the passenger side of the radiator, though my vehicle doesn't appear to have this. Can I just not see it or something?


Any ideas concerning why my fan would have stopped working when I changed the thermostat - and now that the car actually gets up to temp? The fan doesn't turn on when the car is overheating either. If I turn the AC on, I hear another fan (one that I cannot see) turn on, but the main radiator fan still does not turn on. I'm thinking maybe I spilled some antifreeze onto the fan during a flush when changing my thermostat, could that be a problem? Any ideas on things to replace?


I'd like to get this fixed before I'm sitting in traffic with the heat on this summer. Please, any ideas will be appreciated. Thanks

[Pineapple]

Probably you need a new fan. Check your fuse first. Unplug the fan. Check for power on the plug. The fan switch is on the rad. Find it unplug it. Fan is constant on when the switch is unplugged so you'll have 12V on the fan plug with key at On. Don't need to start engine. If you you don't have 12V at the fan plug, its fuse or broken wire. If you got 12V and fan still not turning, you need new fan.

[cwayne]

unplug the fan, splice wires and tap it to the car battery (watch polarity). If it doesn't turn = fan dead.

[bafoon]

I installed a new fan motor. It solved the problem of the fan not turning on, but now the problem, once again, is that the fan doesn't shut off. It runs no matter what the temp is. At least my car doesn't overheat anymore.

My particular 4AFE does not have a radiator fan switch plugged into the radiator, I believe it gets the signal to turn on from the coolant temp sensor, which I just replaced. I doubt it has much to do with it, but I'll add that I believe the car is running rich. High HC and a slight hesitation on acceleration at low RPMs. New cap, wires, rotor, plugs. The temperature gauge does indicate normal temp now - once the car warms up.

any ideas why the fan is staying on?

Thanks for the help so far

[73GTV]

thermostat switch is usually how a radiator cooling fan switch operates. If the fan is operating when the coolant is cold, then that switch is shorted. Remove the wire and see if you have 12 volts coming to the fan. Find the thermostat switch and replace it. The internal Bi-Metal contacts only connect when the metals heat up, one at a faster rate than the other which completes the circuit to ground for the fan to run. Thats an old school tip, If I'm incorrect, someone please let me know.

[bafoon]

Thanks for the help!

The thermostat that I already replaced is located inside of the water inlet housing. There is no electricity going to that part, it simply opens and closes according to temperature.

When I search autozone.com for parts, I also find something called an electric fan thermostat though I can't find this in the service manual that I found online. I do find something called a water temp switch in the manual, but it appears to be the same as the coolant temp sensor (see image). I know there are three things on the drivers side of the block: coolant temp sensor, cold start injector switch, and another part that resembles these 2 and sort of just pulls off instead of screwing in (I'm guessing not related to coolant system because the pressure would probably blow the part off, but I'm not sure about that). Could this be the water temp switch?





The service manual says there is a water temp switch on the block in this image for the 4afe, but also shows this switch on the passenger side of the radiator of other similar engines. I don't any sensor/switch-like parts located on the radiator of my car, but haven't taken off the under cover to look at the front/side of the radiator. Maybe I'll check to make sure the coolant temp sensor wire is not shorting out. First, let me ask an important question:

Driver's side of block, 2 parts (coolant temp sensor switch and cold start injector switch)... the one with the green adaptor is the CTS and the brown adaptor is the cold start injector switch, is this correct?

[Pineapple]

With key at On and fan running, unplug the "Temp Switch". Fan will stop if you got the right one.

[bafoon]

Actually, from what I read I think the fan is supposed to turn on if you unplug the "fan switch."