Author Topic: Fan is not working. Where to start diagnosis?? (Read 5138 times)

mtnbob · « **on:** April 27, 2008, 06:46:58 pm »

86 Golf Diesel 1.6 N/A
My engine starting warming up quite a bit on uphills this weekend. I noticed that my fans never kicked on. Where do I start with diagnosing? I have never seen the fans on and I didn't have any probs on the flat highways in the winter, but I have to fix it before summer.

rallydiesel · « **Reply #1 on:** April 27, 2008, 07:25:18 pm »

First thing to do is pull off the electrical connector on the lower left-hand corner of the radiator. Then jumper the connections. The fan should turn on when the terminals are jumpered. If not, the fan is bad. If the fan turns on, it could be the radiator thermoswitch. Get a new one (they're cheap). If that doesn't work, there is a faulty connection somewhere.

mtnbob · « **Reply #2 on:** April 27, 2008, 09:14:18 pm »

Ty I'll start on it tomorrow night

burn_your_money · « **Reply #3 on:** April 28, 2008, 07:34:25 am »

I'd start by manually spinning the fan to make sure it isn't siezed. They rarely come on so it isn't uncommon.

if it does come on when you jump the thermo switch it's definitly the bad piece, or it is too hot for your application.

if it does not come on, it could be the relay. Pull that out and jump it. You can also remove the relay and thermo switch and jump one end of it and check for continuity. This will tell you if it is the primary or the secondary circuit.

If you have AC there are a lot more variables and the above does not fully apply.

mtnbob · « **Reply #4 on:** April 29, 2008, 11:39:05 pm »

dang, of course i have ac :shock:

Possum79 · « **Reply #5 on:** April 30, 2008, 09:54:02 am »

I have AC in my rabbit and could not get the fan to turn on. The fan is wired the an AC relay which makes it a little harder to troubleshoot. If i turned on my AC to a high setting the radiator fan would come on. My thermo switch was shot.

shegel · « **Reply #6 on:** April 30, 2008, 12:09:40 pm »

i had the same problem in my 86 golf w/ac what happened for me is the wiring loom that ran under the battery had coroded and acid had eaten through the wires. :roll: hope this helps

later

jtanguay · « **Reply #7 on:** April 30, 2008, 12:50:52 pm »

there is also a resistor for a/c equipped cars. it is for the 'low' fan speed

mattbondy · « **Reply #8 on:** May 03, 2008, 10:36:51 am »

The first thing to check is definitely the 20 year old wiring. If there is a break in the insulation the copper just oxidizes and falls apart. I found two or three breaks in these wires when I bought my Jetta. You can quickly check the motor by unplugging the connector and shoving a 9V battery in there. You may have to give the fan a little shove but it should turn at a slow-moderate speed. It should also turn pretty easy by hand but I would be careful. I doubt it could take your fingers of (mine is rather thick plastic). Another quick test is to jumper the relay on the top of the rad. This can also help test the wiring. There are two control circuits. The fan should always activate if the coolant temperature becomes too high. It should also activate if the AC is on. If these all check out then the thermoswitch is likely the culprit. You can check that too by pulling it out and putting it in a pot of boiling water using an ohmeter to see if it closes. The problem with this test is that the thermoswitch is located such that it constantly covered in coolant so you need to block the hole.