Cooling Fan Woes - How to test to see if any good.

Tim Groth

SCCoA Member
I've come to conclude today that my Radiator fan has taken a dump on me, for it failed to engage while driving causing my car to over heat. I pulled the CTS which should cause it to engage and nothing happened. Turned the A/C on which I thought also caused the fan to kick on and all it did was turn the pusher fan on.

Is there any other know ways to test the fan itself to see if it's in fact dead. I mean seems pretty enclusive to me at this point however I don't want to rule anything out prior to changing.

Also I have an 89-93 style fan, I know the connectors are different - out side of this anything else needing to be changed to make it work on a 94?

Thanks!

-Tim
 
You can disconnect the power lead to the fan an use some insulated wire to jumper the connections to the battery. You might have a blown fusible link between the fan and the main power buss (big fuse box under the hood).
 
I had the same issue one night, and it turned out to be the fusible link, like LJ said. Check from the fusebox all the way to the fan motor for any burned up connectors. That was my issue.
 
The first indicator that the system knows there is a problem is the fact that the front pusher fan is running. That fan hardly ever runs, but will run if there is a problem with the puller fan. First off, this is for a '94? right? Other than what has already been stated, there are several things to check:

1) Does the puller fan run at all when you turn on the AC? If not, is there voltage at the wiring pigtail at the fan motor? Disconnect the plug from the motor and test to see if there is voltage with a volt meter.

2) If there is voltage at the volt meter, then that is just about a dead give away that the problem is with the fan motor. Will the fan motor turn at all? (try turning the fan blades with your hand. Sometimes the motor will lock up tight.) If it is locked up, then you definitely need to buy a new motor. NOTE that if you buy a new motor (for the '94 - '95), you will need the 2 speed puller radiator fan, not the single speed pusher fan. The motor is kinda hard to find. NAPA can get it, but the cheapest and quickest place that I found was Autozone. You have to special order it, but they're pretty quick at getting it shipped. You might want to also remove the fan shroud from the car and plug 12 volts directly up to the fan to see if it works.

3) The second thing to check is the 60 amp fuse in the power distribution box under the hood. The fan pulls alot of current, and tends to cause the fuse to get really hot and sometimes melt the wiring and start charring one side of the fuse. The 60 amp fuse is the yellow ones. Check your owners manual for the specific one for the fan.

4) The third thing to check (if you don't have power to the wiring pigtail) is the PCM relay module (sometimes called the IRCM) which is a small metal black box that is mounted just in front of the air filter box. This box contains multiple relays that control different things...with the fan motor being one of them.

5) The last thing to check is the coolant temperature sensor that is mounted on the pipe on the right side of the intake manifold. There are two coolant temp. sensors. The one mentioned above sends its info to the computer and the temp is used for engine management. The other temp. sensor is mounted next to the thermostat and is only for the gauge on the instrument panel. Anyway, you can check the resistance across the sensor with an ohm meter (or multimeter), to see if it's reading correctly. If you unplug this temp sensor with the car running, the computer should turn on the radiator fan motor on high speed because the signal from the sensor has been lost.

Of all of this, I would definitely suspect the motor first. I've replaced 2 of these motors for my '95. The last time was just last week. In my case, the motor would run for about 5 minutes, and then shutdown. You could shutdown the engine and let sit for 10 - 15 minutes, and then the motor would run again for 5 minute and shutdown again. I checked all of the other stuff, and then figured out that I still had 12 volts at the wiring pigtail even when the motor stopped at the 5 minute mark. I replaced the motor and everything is fine. There must be some type of thermal switch in the motor that was shutting it down because it was overheating for some reason. Check the 60 amp fuse in the power distribution box (under the hood) also. I ended up replacing the fuse in mine. The fuse wasn't blown, but one leg of the fuse had gotten really hot at some point in time that it had turned brown. If you do a search, you will see lots of people saying they have problems with the IRCM. I have not had any problems with mine, and it is now 12 years old. Others say they had problems with the coolant temp sensor, but you can check that one quickly to see if it's reading correctly. I found a table of resistance conversions for the sensor on Auto Zone's website for that sensor. Mine was reading fine. If you do need to replace it, it's really cheap.... ~$10.00 - $15.00

Good luck.

David
 
Well guys I got lucky on this one to say the least - I figured it would be the easiest to check the easiest things to do so first, and well come to find out the fuse looked like it caught fire.


100_0788.jpg


Replaced with a new Fuse and now we have a fan that works again.

-Tim
 
Well guys I got lucky on this one to say the least - I figured it would be the easiest to check the easiest things to do so first, and well come to find out the fuse looked like it caught fire.


100_0788.jpg


Replaced with a new Fuse and now we have a fan that works again.

-Tim

Man, I'd be hunting down whats causing that in the first place..... before you end up with something worse :eek:
 
I would concur. That fuse didn't get burned up just for the heck of it. Likely the fan is on it's way out and causing a lot of current draw or is really hard to start.

you can buy a replacement motor for them.
 
Yeah I agree completely with you guys, however I'm saying that when i got off work at 9pm last night it was nice to see a blown fuse and not something more time consuming at that point in the night.

I have Thursday off work where I plan to just do car related projects so this will def. be looked into since its not something I want to cause further problems down the road.

-Tim
 
lol i had a fuse that looked just like it in my 94, only after replacing it the fans still dont work :(...well they do when i turn the ac on...
 
Back
Top