Mrflip99

My radiator fan is not coming on when the engine is hot. I have jumped the fan switch with a paper clip and found out the fan only comes on SOMETIMES when being jumped. Fuses under dash and underwood have been checked and radiator fan relay is ok - I hear clicking when plugging/unplugging. Also the fan only comes on sometimes after turning off the engine (when above normal temps) which I believe is the ECT thermoswitch B . I originally thought it was the fan switch (ECT switch A) by the T-STAT housing which I have already replaced but after finding out the fan only sometimes works after jumping, that has been ruled out. I have also noticed, the fan spins normally, but not excessively - shouldn't it be high speed and quite loud?

I think the thermostat is ok bc the car only overheats at idle. It is my understanding that if the thermostat was bad (not opening) the car should overheat really fast. Turning on the heat in the car starts to cool the engine as a quick fix.

Ideas? Fan going bad? Electrical wiring bad? Radiator Fan module? I have yet to jump the fan directly with the battery....

holmesnmanny

Sounds like the fan motor itself is possibly bad. If the ac fan comes on but not the radiator fan that would point to the motor probably being bad. They should both be coming on when the ignition is ever on. Only the radiator fan will come on when the ignition is turned to off but only in hot weather.

Mrflip99

holmesnmanny - so with the ignition to ON, when i short the fan switch, both fans should run?

i'm not sure if the AC fan turns on, i'll check again. I've only seen the radiator fan turn on.

At one instance, I shorted it with engine on -- fan didnt turn on. Left paper clip inserted/shorted. Turned off ignition. Hit the fan with a tool a couple times. Turned on ignition and it was running. So I don't know if it was maybe a loose connection with fan motor, was bc of the short being left in pre-ignition.

holmesnmanny

Yes, with the ignition on and you short the fan switch connector the fans should both turn on. See what happens when you do that.

Mrflip99

I shorted it and like before neither fans turn on. If I bang on it, the driver's side will turn on and spin but not as fast as I would think it should be. Its not loud like other cars i've seen in videos. As for the passenger side fan, it won't turn on even after banging. Only if I manually turn the fan initially, will it spin. Same speed as the other, not very fast.

Turning on the A/C in the car will turn one fan, no problems, but again not too fast. I find it out that when jumping the switch, I have to intervene to get it going for either fan, but with the A/C on, one fan turns on normally.

I did get into a fender bender back in January (maybe going 10mph, dented the front in a bit and had to pull it out with some ratchet straps) - radiator was fine no cracks, so I figured everything was ok - maybe it damaged the fan motors?

tim73

I would check the grounds to the fans. With the temp switch jumped(key off). Disconnect the harnesses from the switches. One pin on the engine side harnesses should read 12v to the negative battery lug. The other pin you should be able to have continuity .1ohm, to the negative battery lug. If continuity is over 5 ohms, then you have a loose/bad/missing ground.

jollyhonda

Check to make sure the electrical connector to the fan is not melted and that the contacts are doing their thing. Unplug the connector and give it a thorough inspection. And then it may just come down to a bad fan motor. If the brushes are wore out, you could get an intermittent/poor performing fan.

Mrflip99

thanks again for all the replies. I have replaced both fan motors and now both turn on consistently when jumped with switch A (near t-stat housing). However, when not jumped and the temp gauge starts to go up, fans don't turn on... is it the thermostat or fan ECT switch B?

how do i know if the coolant pump and thermostat is working? if either wasn't would the car overheat quickly?

rockycat

If jumping the switch turns the fans on then replace the switch.

Mrflip99

Fan switch was already replaced. Is this to say the new fan switch could be bad?

holmesnmanny

Crack open the bleeder bolt at the top of the thermostat housing and see if any air comes out. It's a 12mm head bolt. Close it after about 5 seconds when only coolant comes out. That should do the trick.

Then check if the fans come on after the car warms up.

Mrflip99

Well guys it seems like I can't get a break... I let the air out and retightened the bleeder bolt and as I was retightening, the top portion of the bleeder housing broke off.

I see that there is still some threading on the main housing. The original bleeder bolt won't fit because it is already touching the end of the female housing.

Perhaps I can just get a bolt the same size as the original and close it off?

Bleeder bolt on top portion of housing that broke off.

R

holmesnmanny

You need to head down to the nearest pick-n-pull junkyard and pick up another housing.

Mrflip99

Can I just buy a bolt the same size from home depot and plug it? Pros and cons of this?

holmesnmanny

Didn't the housing itself crack ?

Mrflip99

Yes but only the top portion (connected to the screw). Instead of the valve opening sticking up, now its just flush with the rest of the t-stat housing. I don't plan on keeping this car for long and probably just for the 5 min commute to the train station. Would it be ok to just plug it with a bolt?

holmesnmanny

Ideally it needs a way to vent out of that bolt. It's possible you can make do without it but you will need to monitor if the car overheats upon the first start up. The issue was that an air pocket was lodged in there and wasn't allowing hot coolant to touch the fan switch which is why the fans weren't turning on.

I would really suggest just picking up another housing. It won't cost much at all.

It really sounds like trying to plug that hole with a bolt will be more work than just picking up another housing.

Mrflip99

Thanks again for the quick reply. I will try out the bolt in the interim until I get the new housing from a junkyard

holmesnmanny

You would be best to just jb weld it if you can't get to a junkyard soon.

Mrflip99

Are u referring to welding the bleeder screw to the valve?

holmesnmanny

Take the bolt off and then jb weld the part that cracked off the housing back on. Let it cure for a few hours and then put the bleeder back on and reinstall the coolant with it cracked open and the front of the car jacked up as high as possible. When coolant streams out of the bolt, close it. Keep filling up the radiator until it's full. Close it. Start it up and see if the fans come on after the car has completely warmed up.