fan question
Thread Starter
Teching In
Joined: Aug 2004
Posts: 42
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From: Drums, Pa.
fan question Did some searching and found no similar question, so excuse me if this sounds
stupid.
I'm using a single fan and single relay.
What would happen if I joined the hi fan and low fan wires from the pcm, together, at the fan plug ?
I know guys are using just the low speed fan without any problems but in
the summer with the a/c on, will I need the hi speed ?
Jack
stupid.
I'm using a single fan and single relay.
What would happen if I joined the hi fan and low fan wires from the pcm, together, at the fan plug ?
I know guys are using just the low speed fan without any problems but in
the summer with the a/c on, will I need the hi speed ?
Jack
The way the fbody setup works is that then the low speed signal is sent to the fan relays it closes that one relay. When the high speed condition is met, the high speed relays are thrown on in conjunction with the low speed relay. If you wire it up to the low speed signal on the PCM you won't have a problem.
What he said.
When the slow speed relay is energized, the fans run in series and each fan gets 6v running them in slow speed.
When all three relays are energized, the fans run in parallel and each fan gets 12v running them in fast speed.
This setup will only work with two fans and three relays. This is the way the factory did it. If you only have one fan. Just wire it up to the slow speed output on the PCM. If you want two speeds, you will need another relay and some serious resistors to knock the voltage down.
When the slow speed relay is energized, the fans run in series and each fan gets 6v running them in slow speed.
When all three relays are energized, the fans run in parallel and each fan gets 12v running them in fast speed.
This setup will only work with two fans and three relays. This is the way the factory did it. If you only have one fan. Just wire it up to the slow speed output on the PCM. If you want two speeds, you will need another relay and some serious resistors to knock the voltage down.
On The Tree
Joined: Oct 2004
Posts: 100
Likes: 0
From: St.louis
So, what would you need to do to make one fan stay on high, and have it on a switch (when the car is turned off).
and is the primary reason to do this for wieght? I do know those fans wiegh a lot.
thanks
and is the primary reason to do this for wieght? I do know those fans wiegh a lot.
thanks
If you only have one fan, wire the ground terminal of the relay to the PCM. If you want it to run all the time, wire it to the "engine cooling fan relay 1 control" pin on the PCM. If you want the fan to cycle on and off depending upon temperature, then wire it to the "engine cooling fan relay 2 and 3 control" pin on the PCM.
To have a switch, tap off of the wire running to the PCM to a switch under the dash then to ground under the dash. This will allow you to manually ground the relay turning on the fan.
Make sure the relays have 12V hot, not ignition hot. That way you can turn on the fan even if the car is off.
To have a switch, tap off of the wire running to the PCM to a switch under the dash then to ground under the dash. This will allow you to manually ground the relay turning on the fan.
Make sure the relays have 12V hot, not ignition hot. That way you can turn on the fan even if the car is off.
