92 voyager 3.3L cooling fans won,t turn on

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I have a 92 plymouth voyager. The cooling fans won't turn on. I,ve checked the fans they both work directly connected to the battery. I've unplugeed the sensor (near the thermostat) and they still did not kick on. Does this mean the relay is shot? any input would help alot . I,m pulling what little hair I have left.

posted by  fishn4dabig1

simply unplugging the sensor most likely would not engage the relay. If it works similar to most systems then the sensor's resistance will decrease with the temp of the engine until it reaches near 0-ohms. which will ground the relay completing the circuit and engage the fan(s).

Ok in simple terms. if the sensor is a one wire sensor, when you unplug it connect the wire to a good ground, then listen for the relay to click. If it does then the sensor is bad, if not then the relay is most likely to blame. Due to the low cost of each and troubleshooting it is giving you a headache, just replace both.

If you do want to continue with the troubleshooting let me know and I can walk you through a few checks.

Here are a few more things to check:

the relay should have a constance 12V on on of the terminals, if not it may just be a fuse
is the coolant level correct, if not the sensor may not be in the water and will not read correctly
one of the fans is sometimes connected to the A/C switch, does one of the fans come on with the A/C?

posted by  corbett_auto

The sensor is a 2 wire plug and I,m not even sure it,s the right sensor, but its
the only one that seems to attach to the thermostat housing. and I don't know which relay it is ther is 4 on the drivers side fender and 2 on the passangers side. does anybody know where to get the prints for this, without having to buy a chiltons.but I definetly will take your advise and just replace all the probabilities of cause. Thankyou for your help.

posted by  fishn4dabig1

I forgot to mention that the fans do not work when A/C turned on. and even stranger is that the dash guage reads normal operating temp, while the van is overheating. Ive been reading around to find out which relay I need to check but there seems to be some kind of confusion on the amount of relays on the driver side fender. I only have 4 relays some people seem to have 5.?

posted by  fishn4dabig1

Have you recently had to add a large quantity of coolant to the system?

I suspect the problem may be a vapor lock condition.This happens when the coolant level drops and more coolant is added and the engine is not vented and air is trapped in the top of the engine. The sensors will not read correctly if they are not submerged in coolant.

If this is the problem the cure is very simple. Try to find a sensor on the top of the engine (but not located in the thermostat housing). Remove it and add coolant until the level reaches the threads, then reinstall the sensor and finish filling the radiator. If you can not find a sensor (or plug) to remove you can always just remove the thermostat housing and follow the same steps.... and while you are at it go ahead and replace the thermostat (remember to bu a new gasket).

posted by  corbett_auto

just by chance if this is not the problem, can I tie into the ignition directly and have the fans on as soon as I turn the car on. (just as a temp fix until I get my new car) and if I can do this should I tie a inline fuse in?

posted by  fishn4dabig1

That would be fine to tie in with the ignition switch, and yes use a fuse. 20amps should be a good size. Just be sure to tie into a wire that is only hot with the key on....

Also, most parts places have a thermostatic switch you can mount under the hood to control the fans.

posted by  corbett_auto

Thank you very much for your help, I really appreciated all of your input. Also nice pictures. Dave...

posted by  fishn4dabig1

Use this site, with access number 123456789.


Just in case you have problems:

The power to the radiator fan is via a fuseable link from the battery. The interposing relay is controlled by the powertrain control module.

The wire from the fusable link to the relay is grey. From the relay to the plug, it is light green. From the plug to the fan it is light green, or black, or black & white.

The +12V to the relay coil is dark blue. The other side of the coil is dark blue with pink trace, finally connected to pin 31 of the powertrain module (cooling fan relay).

posted by  Wally

Thanks for the specifics Wally. He should be able to trace down the problem with this info.

BTW: after you enter in the access ID the link does not take you to the info. Is there a specific branch to search? Just in case he needs more info...

posted by  corbett_auto

I found it it in the third Uni dropdown choice

posted by  Wally

Totally awsome information!!! I needed something like that. Thanks Wally!!:thumbs:

posted by  dvdrose18

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