Fans keep running after engine stop. Which temp?
06-07-2007, 04:20 AM
#1
Racer
Thread Starter
Join Date: Feb 2006
Location: Madrid, Spain
Posts: 320
Likes: 0
Received 0 Likes
on
0 Posts
Fans keep running after engine stop. Which temp?
I've read all post about this, and I think I know the theory (the temp sensor in top of the engine and so).
I noticed some weeks ago (as the weather gets warmer here) the fans didn't stop after engine stop. They stop after a while (5 minutes or so). I thought it was ok.
The question simple: Does it happen to you all the time above 30ºC external temp? How much time is it working after shutting the engine down?
The reason for my q's is that the battery is getting weaker (slower initial cranking) and I'm wondering if my sensor is a little too "cautious" and needs replacing. And also I would like to confirm that the fans cannot be triggered in by any other faulty sensor after engine is shut down. And finally if a faulty temp sensor will drain battery out or there is something like a time relay to bypass it 5 minutes later.
Thanks a lot!
EDIT: 87 S4 5spd
I noticed some weeks ago (as the weather gets warmer here) the fans didn't stop after engine stop. They stop after a while (5 minutes or so). I thought it was ok.
The question simple: Does it happen to you all the time above 30ºC external temp? How much time is it working after shutting the engine down?
The reason for my q's is that the battery is getting weaker (slower initial cranking) and I'm wondering if my sensor is a little too "cautious" and needs replacing. And also I would like to confirm that the fans cannot be triggered in by any other faulty sensor after engine is shut down. And finally if a faulty temp sensor will drain battery out or there is something like a time relay to bypass it 5 minutes later.
Thanks a lot!
EDIT: 87 S4 5spd
06-07-2007, 01:56 PM
#2
Rennlist Member
Rennlist Site Sponsor
The intake plenum air temp sensor is the only one that will run the fans with the ignition switch off - unless a relay is stuck!
Yep, it will drain the battery if it runs long enough - no timer in the circuit, just a temp switch.
Make sure that the alternator belt is TIGHT.
Yep, it will drain the battery if it runs long enough - no timer in the circuit, just a temp switch.
Make sure that the alternator belt is TIGHT.
06-07-2007, 01:58 PM
#3
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
Member
There are two sensors on the automatci cars, but since you have a 5-speed the only switch that will cause the fans to run after shutdown is the one on the top of the intake manifold. It's quite easy to replace with just the two wire connections, and there's nothing to leak out when you have it off.
I had a problem with fans running on like this. It started only after washed the engine and rinsed it with water. Some water found its way into the switch. I tried drying the switch but that didn't help, so a new switch was installed and the problem was cured.
The only times that the fans have run after engine shut-off in normal driving was after a long uphill drive at 80+ MPH in 35C heat, AC running, with little cool-down time before shutting the engine down. The temperature gauge was showing a little above the third mark, but still well below the red 100C mark, before I stopped the car.
I had a problem with fans running on like this. It started only after washed the engine and rinsed it with water. Some water found its way into the switch. I tried drying the switch but that didn't help, so a new switch was installed and the problem was cured.
The only times that the fans have run after engine shut-off in normal driving was after a long uphill drive at 80+ MPH in 35C heat, AC running, with little cool-down time before shutting the engine down. The temperature gauge was showing a little above the third mark, but still well below the red 100C mark, before I stopped the car.
