Cooling fan Problems

smartech · #1 (**permalink**) 10-05-2009, 10:37 PM

Hi there, I have an 1987 Jetta 1.8 8v and have a couple of questions about the cooling fan. I once drove the car pretty hard once and turned it off and parked it but noticed the fan was still running even though the car was off. Is this normal? At the time i didn't think it was normal because it was on for a good 2 minutes so I tried fiddling around with the Fan thermo switch ect, and the fan turned off. But now everytime I see the fan, it doesn't look like it works anymore. Is the fan supposed to come on as soon as you start the car? Or does it kick in later on once the temp increases? I drove it around for a bit but still the fan didn't come on. Maybe it wasn't lomg enough for the fan to kick in I don't know... So i replaced the fan thermo Switch which did nothing. Any help would be appreciated.

**its the rad fan, not the Ac fan as my car doesn't have AC.

perrib · #2 (**permalink**) 10-08-2009, 10:31 AM

That is how the system works. your engine gets hotter due to heat soak when you turn it off. The fan runs until the engine cools down.

smartech · #3 (**permalink**) 10-14-2009, 12:42 AM

Ok thanks! Yea I'm new to this car so I wasn't sure how the fan system opperated. I figured out that everything is working the way it should

Tigys599 · #4 (**permalink**) 10-17-2009, 12:15 PM

mine was doing the same thing, I thought it was messed up, so I added a toggle switch, that way my fan shuts off when I shut it off... although it was sort of pointless.

Ninja Please · #5 (**permalink**) 10-17-2009, 02:14 PM

Quote:

Originally Posted by Tigys599

mine was doing the same thing, I thought it was messed up, so I added a toggle switch, that way my fan shuts off when I shut it off... although it was sort of pointless.

You should remove that switch before you accidently hit it while you are stuck in stop and go traffic or something..

Tigys599 · #6 (**permalink**) 10-17-2009, 02:38 PM

yeah, I will do that. I actually did that once already, but i caught it before it over heated.

Quote:

Originally Posted by Ninja Please

You should remove that switch before you accidently hit it while you are stuck in stop and go traffic or something..

Ninja Please · #7 (**permalink**) 10-17-2009, 04:04 PM

Because your engine is a longitudinally mounted engine with 4 cyclinders the following is probably slightly less true than for a VR6 motor. but my Vr6 moter takes several, several hours to cool -Much longer than any car I have ever owned. I imagine the post engine shut off fan cooling is essential. but the VR6 cylinders share a single cylinder head and the Vee is only at 10 to 15 degrees -I think this probably contributes to why they stay hot so long after a drive.

perrib · #8 (**permalink**) 10-19-2009, 05:54 PM

Quote:

Originally Posted by Tigys599

mine was doing the same thing, I thought it was messed up, so I added a toggle switch, that way my fan shuts off when I shut it off... although it was sort of pointless.

Major bad idea, it is easy to recharge a battery. A head gassket takes a lot longer. Use that switch to turn on the fan in case of a thermo switch failure.

CafeRacer · #9 (**permalink**) 11-01-2009, 01:13 AM

On the note of thermo temp switches here. In my car unless Ive got air going into the rad I can watch the temp guage rise well past normal running temperature untill the high speed fan kicks in like when you shut off the motor. The secondary fan speed doesnt seem to kick in. Is this the temp sensor thats gone?

perrib · #10 (**permalink**) 11-01-2009, 07:01 PM

It could be. Bypass it to see if low speed works.

CafeRacer · #11 (**permalink**) 11-02-2009, 11:43 PM

how would one do that? I changed the sensor and it didnt turn on the fan at any point. Even after turning off the car.

Could the thermostat not be opening up and keeping the hot fluid from the rad?

perrib · #12 (**permalink**) 11-03-2009, 10:58 AM

If your thermostat did not open the engine overheats and pushes out coolant. A Thermostatic radiator fan switch for your Jetta is functioning properly has 12 volts from the battery fed to it and as the temperature rises 12 volts is connected to low speed fan feed and later as the engine temp rises power is transfered to the hi speed wire. Using a Jumper wire from the 12 volt supplied to the switch and connecting to the other two will actibvate the two speeds. A manual from robertbentley.com has the wiring diagram which you can trace open circuits. The most common besides a defective themo switch is corroded connections and worn out fans.