Tech questions please help
10-27-2007, 11:40 AM
#1
Rennlist Member
Thread Starter
Tech questions please help
How hot does the engine need to be before the ac cooling fan Kicks on?? I just replaced mine as the old one had seized. I ran the car with the ac on for about 10 min and nothing. Also when I selected the defrost mode the fans in the car cut out?? I have a new resistor an plugged it in but have not mounted it yet. Any suggestions btw it's a 90 c4 coupe
10-27-2007, 12:41 PM
#2
Three Wheelin'
AC fan has nothing to do with engine temperature. The condenser fan (in front left corner) comes on at slow speed immediately the a/c is switched on. Slow speed requires the ballast resistor in circuit.
I'm assuming you have the right resistor. The one for the condenser fan is mounted above the condenser in the front left wing. The oil cooler resistor is in the front right wing and the rear blower resistor is mounted in the blower plenum on the left side of the engine bay.
When you select "Defrost" all blowers should be running at fast speed and a/c should be on. If the blowers cut out you have a problem. Do ALL blowers cut out - or just the internal dash blowers??
Regards
Dave
I'm assuming you have the right resistor. The one for the condenser fan is mounted above the condenser in the front left wing. The oil cooler resistor is in the front right wing and the rear blower resistor is mounted in the blower plenum on the left side of the engine bay.
When you select "Defrost" all blowers should be running at fast speed and a/c should be on. If the blowers cut out you have a problem. Do ALL blowers cut out - or just the internal dash blowers??
Regards
Dave
10-27-2007, 12:59 PM
#3
Rennlist Member
Thread Starter
My fan (ac cooling) is not kicking on when I select ac and the ac is running. If I depress the defrost button the fans inside the car run a few seconds then cut out.
10-27-2007, 01:07 PM
#4
Three Wheelin'
I think you have a couple of different problems here.
If the internal fans cut out after a few seconds it's almost certainly because the rear blower is not running. The system relies on a pressure difference between the cabin and the air supply from the engine compartment. If the rear blower isn't running the CCU will shut down the internal blowers.
The a/c (condenser) fan not running could be a problem with the ballast resistor, a fuse, a relay or the CCU itself. The relay for all 3 blowers (rear, oil cooler and condenser) are all the same and you can swap them about to clarify the problem.
A common problem with the rear blower is that it can blow it's fuse. Check that you have a 30 amp fuse fitted - even if the label says it should be 25 amp. Porsche uprated the fuse to stop it blowing. You can check the operation of the rear blower by just turning the temperature **** off the blue dot towards the red dot with the ignition on and the rear blower should start up at slow speed.
There is always the possibility that you may have a problem with the CCU itself but I'd check all else first since the CCU is expensive - although they can be repaired.
Hope that helps.
Regards
Dave
If the internal fans cut out after a few seconds it's almost certainly because the rear blower is not running. The system relies on a pressure difference between the cabin and the air supply from the engine compartment. If the rear blower isn't running the CCU will shut down the internal blowers.
The a/c (condenser) fan not running could be a problem with the ballast resistor, a fuse, a relay or the CCU itself. The relay for all 3 blowers (rear, oil cooler and condenser) are all the same and you can swap them about to clarify the problem.
A common problem with the rear blower is that it can blow it's fuse. Check that you have a 30 amp fuse fitted - even if the label says it should be 25 amp. Porsche uprated the fuse to stop it blowing. You can check the operation of the rear blower by just turning the temperature **** off the blue dot towards the red dot with the ignition on and the rear blower should start up at slow speed.
There is always the possibility that you may have a problem with the CCU itself but I'd check all else first since the CCU is expensive - although they can be repaired.
Hope that helps.
Regards
Dave