Radiator fan wont come on

[Kainnen]

I have a 91 plymouth laser N/T 2.0L, and my radiator fan refuses to come on for the last few weeks now, just put in new tstat, coolant, rad cap. I also switched 2 relays around to see if the rad one wasnt working but the relay seems fine. So my guess is a sensor, there seems to be 3 sensors, one for the gauge which i was told wouldnt effect my radiator fan, then one next to it then one directly in the radiator. Do you guys think it would be the one in the radiator and if so anyone have a picture or model number for it cause my local shop didnt seen to have one.

 

[versatilx1]

Please check to see if its your 20amp fuse in for radiator low or high in your fuse box in the engine bay that might help bro

 

[Kainnen]

I dont see a rad fuse labelled on the box just a rad relay i believe, the bigger fuse type thing with the black tops. Is there a fuse as well in there?

 

[steve]

Main fuse 2 on the battery post feeds the radiator fan via the radiator fan relay. The control side is powered from the ignition switch to the relay coil and grounded by the thermosensor in the bottom of the radiator. Checking the fuse and sensor would be tops on my diagnostic list.

Steve

 

[RobertETHT2]

Had the same issue - looked at everything and finally applied 12 volts to the motor - it was dead. Took it out and apart, cleaned all the gunk out of it and reassembled it. It worked!! BUT - I sure didn't want it dying in the middle of stop & go traffic, so I picked up a new motor at Oreilly Auto Parts for about $40 - Been going strong since!!! Good Luck in tracing your problem down!!!

 

[Kainnen]

Hooked the fan up directly to a 12v power source and it comes on. I swapped the relays from headlights and fan and the lights work with either but still no fan. I noticed each relay seems to have a different number i believe it was like D1, D2, D3 or maybe it was an R but something like that. Is that like a different power rating? So back to the 3 sensors, if one of those sensors don't work will the fan not come on? One of the guys at a garage told me the temp gage sensor should have nothing to do with the fan turning on but I've read differently on this forum.

 

[ColdAudio]

the fan turns on based on the coolant temp sensor telling it to, which is located at the bottom of the rad, a 2 wire plug goes into it. that is all that turns the fan on.

 

[steve]

I guess that easier to understand than what I posted above. It's hard to transpose wiring diagrams into words sometimes.

Steve

 

[ColdAudio]

I guess that easier to understand than what I posted above. It's hard to transpose wiring diagrams into words sometimes.

Steve

its the wiseman talk that confuses the newbies ! is there any way to check if the sensor is bad besides swapping in a new one? i dont have time to go to the shop/junkyard, whenever i get home from work its way too late

 

[steve]

You can try unplugging the connector and grounding green/black wire with the ignition on. If your fan comes on you know that the power, relay, and fan are good. Check that the black wire has continuity to ground. That pretty much leaves the switch. You can check it by getting the coolant temp above 185F and making sure the two pins have continuity.

You may find once you check the temp sensor at the bottom of the radiator that the connector is disconnected or corroded.

Steve

 

[ColdAudio]

alright coool thanks for the info man, so helpful! i remember at one point i tried using just the power that went into the rad fan without the temp sensor, the line read 12v but the fan wasnt moving, but that fan also died so who knows the real cause, once i find the cause of that mpi fuse always blowing ill work on this... sigh damn dsm takin all my free time

 

[Kainnen]

Wow do i feel stupid, the solution to my problem turned out to be something really dumb. My overflow bottle was empty for some reason that prevented the fan from coming on i never knew that would happen i thought the overflow was just if you over filled the rad. So soon as i had some coolant/water in the overflow bottle the rad fan came on after a couple minutes idle.

 

[ColdAudio]

nice, glad to see you find your fix
as for me, i found that the rad fan fuse in the main box near the battery is blown so i rewired the fan back to stock, will replace the fuse tomorrow and hope for the best! my question is this: how do you get that fuse out? since just tugging on it didn't move it at all....

 

[Kainnen]

On my car the only fuse for the Rad that ive seen is the big 4 prong ones with the black tops under the hood in the black fuse box which i believe are relays, mine just pulls right out although some took a bit of force. I swapped mine with the headlights just to make sure it was working, there was a different number on each one but they did work swapped.

 

[ColdAudio]

nah its a big one in the fuse box right next to the battery with the 4 fuses, is there a screw or anything that holds it in place? i see 2 positive lines that run into the box, are these what is holding the fuse down?

 

[Kainnen]

No screws were in mine but i had to wiggle them back and forth to get most of them out, they were in there good.