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Originally Posted by David N.
Does anyone know the exact conditions for the engine compartment cooling fan to activate? My car has a tendency to run a little warm (95 degrees Celcius according to engine coolant temp diagnostic), but I took it for a spirited run in the mountains today and it was hitting 105 and I noticed the cooling fan still wasn't turning on (this was driving between 30-60mph). The fan came on going home when I was at 94 degrees on the freeway at 80mph. If it uses the coolant temp as its condition, doesn't seem like it's being very consistent.
If it isn't activating consistently, is there a common sensor problem or something that would be to blame? Thanks guys, I tried searching the forum but wasn't having a lot of luck.
-David
Ocean Blue 2000 S
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Hi,
The Engine Compartment Purge Fan is triggered by the DME control module as a function of the engine temperature, engine compartment temperature and vehicle speed. There are several vaiables involved, so you may not find a discernible pattern for it's operation.
The issue may be a bad Engine Compartment Purge Fan Relay. It is #8 in the #2 Relay Panel (in the Trunk). The Relays are set in two rows - Top Row - #1-6 (L-R), 2nd Row #7-12(L-R).
A fault (
P1674) is detected and stored if the engine speed is greater than 80 rpm and the battery positive voltage lies between 7.5 Volt and 17 Volt.
You can check the relay with a multimeter (always a digital one) as follows:
- 1. Connect multimeter to fan relay (connection point 8 in the rear) terminal 30 and ground.
Display: approx. 12 V. If nothing is displayed, check fuse B4.
2. Connect multimeter to fan relay terminal 86 and ground.
Display: approx. 12 V. If nothing is displayed, check the DME relay.
3. Check the fan relay. On the relay base, jumper terminal 30 and terminal 87 with a test cable.
If Fan starts: Relay defective
Hope this helps...
Happy Motoring!... Jim'99