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-   -   Test if Fan Works? (http://www.318ti.org/forum/showthread.php?t=19307)

bmw318tiChic 11-14-2007 03:54 AM

Test if Fan Works?
 
I am in the process of rebuilding my car since my accident, and I started my car for the first time in months :D My radiator fan worked the first day that I turned it on. Two days later, I started my car again and just let it idle, and the fan wouldn't work. My car was actually overheating some, and the fan still didn't work.

Is there a way I can test if the fan works or not? It just seems weird that it would work one day, and not the next. Is there a way I can test if there is some sensor or switch or something that's causing this problem?

Thank you :)

cooljess76 11-14-2007 04:08 AM

Turn the A/C on and see if the fan comes on. You may have a bad temp switch if it only comes on when the A/C is on. You might also have air in your system which won't allow the coolant to contact the sensor and register the correct temp. I'd start by checking the fan with the A/C turned on and then bleed the air out of the radiator. Make sure it has cooled down before you remove the radiator cap and bleed screw! While bleeding, turn the heater on full blast and add coolant until a steady stream of coolant flows out of the bleeder next to the radiator cap. It helps if you park the car on a hill with the nose elevated. It also helps if you massage the hoses, to push the air trapped in the system to escape. Watch your hands and hair around the belts! Hope this helps, Good Luck.

bmw318tiChic 11-14-2007 04:11 AM

Thanks. That might be it, I'll look into it!

thesk8nmidget 11-14-2007 07:15 PM

Quote:

Originally Posted by cooljess76 (Post 141905)
Turn the A/C on and see if the fan comes on. You may have a bad temp switch if it only comes on when the A/C is on. You might also have air in your system which won't allow the coolant to contact the sensor and register the correct temp. I'd start by checking the fan with the A/C turned on and then bleed the air out of the radiator. Make sure it has cooled down before you remove the radiator cap and bleed screw! While bleeding, turn the heater on full blast and add coolant until a steady stream of coolant flows out of the bleeder next to the radiator cap. It helps if you park the car on a hill with the nose elevated. It also helps if you massage the hoses, to push the air trapped in the system to escape. Watch your hands and hair around the belts! Hope this helps, Good Luck.

good info on bleeding the radiator and checking the fan i gotta remember that one

campaiar 11-14-2007 08:08 PM

One of the fan sensors is in the passenger side of the radiator.

Pull the plug off the sensor and put a paperclip in the bottom hole and one of the top holes of the plug. This will be either the slow or fast fan speed.

Putting the paperclip in the bottom and the other top hole will be the other fan speed.

This is the most reliable way to check if the fan is operable at both speeds.

bmw318tiChic 11-14-2007 10:29 PM

I tested the sensor with the paper clip and the fan only works when the paper clip is in one place, and only at the high speed, so would that mean that the sensor in the radiator is bad? Also, the fan doesn't work with the AC on.

cooljess76 11-15-2007 02:34 AM

http://i135.photobucket.com/albums/q...6/Cimg1568.jpg
When you turned on your air conditioner, did you here it hiss and kick on? Did it blow cold air?

Open up your fuse box. Locate the two yellow relays next to the purple relay. The purple relay is your stage2 fan relay. The yellow relay in the middle is your A/C compressor relay. The yellow relay on the right is your stage1 fan relay. Switch the two yellow relays and see if the fan comes on when you turn the A/C on. They're the same part number so don't worry about messing anything up. Just make sure the car isn't running and the key is out of the ignition when you swap the relays. If your fan comes on after switching the relays and turning the A/C on, you'll know where the problem is.

bmw318tiChic 11-15-2007 04:20 AM

Okay, I'll check that. Thanks.

gimp 02-06-2008 06:53 PM

Old thread, but no one can say I didn't search!!!

I've having a similar problem.

When I did the paper-clip check, only the high-speed fan came on.
With the car running, turning on the A/C DID make the low-speed fan come on.

Right now I'm chalking this up to the fact that I had to rewire the fan (connector was bad, so I removed it and soldered the connections). It worked well for a while, but the low-speed wiring may have failed. I'll have to wait until I get home to check it.

I've got a new coolant temp sensor on the way, and I'll re-bleed when I install it.

Any other ideas?

L84THSKY 02-07-2008 06:38 PM

I'm having the same problem, just checked. The fan works with a jumper in pin 2 and GND, but not pin 3 and GND. Turned on the A/C, and the fan works. Can't be sure what speed the fan works with the jumper, or the speed it works with the A/C on.

What's next, replace the radiator sensor?

Quote:

Originally Posted by gimp (Post 154747)
Old thread, but no one can say I didn't search!!!

I've having a similar problem.

When I did the paper-clip check, only the high-speed fan came on.
With the car running, turning on the A/C DID make the low-speed fan come on.

Right now I'm chalking this up to the fact that I had to rewire the fan (connector was bad, so I removed it and soldered the connections). It worked well for a while, but the low-speed wiring may have failed. I'll have to wait until I get home to check it.

I've got a new coolant temp sensor on the way, and I'll re-bleed when I install it.

Any other ideas?


JNCoulombe 03-02-2008 07:16 AM

If you tried swaping the low speed relay and the low speed still didn't work when you used a paper clip to jumper around the fan switch (as described by campaiar) the fan switch (temperature sensor) is probably not the problem. The next obvious thing to check is the continuity of the fan low speed resister mounted on the back of the fan.

cooljess76 03-02-2008 01:20 PM

Quote:

Originally Posted by JNCoulombe (Post 158237)
If you tried swaping the low speed relay and the low speed still didn't work when you used a paper clip to jumper around the fan switch (as described by campaiar) the fan switch (temperature sensor) is probably not the problem. The next obvious thing to check is the continuity of the fan low speed resister mounted on the back of the fan.

Excellent first post! You're definitely going to be an asset to the community. Thanks for joining and welcome to the forum!

BTW, I just finished drinking a bottle of tequila and smoking a fat ass stogie, sorry if I sound impaired.

tiFreak 03-02-2008 04:14 PM

Quote:

Originally Posted by cooljess76 (Post 158242)
BTW, I just finished drinking a bottle of tequila and smoking a fat ass stogie, sorry if I sound impaired.

still sounds better than some of the stuff I say :rolleyes:

L84THSKY 03-14-2008 04:13 PM

Is there a part # for the fan resistor/connector? I troubleshot my system, and all the voltages are coming from the circuits/fuses. It's either the relays, or the resistor. I know someone said to swap relays, which I did, but that is not 100% conclusive. First off, what speed does the AC kick the fan on, low or high. I think it uses the high speed, which seems to be working. I can't seem to get the low speed working.

JNCoulombe 03-14-2008 06:36 PM

The AC fan should come on at high speed. Perhaps someone else can help with the resistor part number. What I understand is the resistor is located on the back of the fan housing close to the fan motor. It is about 4 inches long and 1/2 inch wide cylinder with two wires coming out the top. The wires run alongside another lead coming from the fan motor to a connector on the bottom corner of the radiator. I'd guess that from underneath the car you could disconnect the connector and measure the continuity of the resistor as well as determine whether voltage is coming to the resistor when the low speed fan should be on.


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