Electric fan override for a/c

[Todd]

I have a electric fan powered by the factory wiring. Some folks chimed in saying the factory electric fan is a pulse width modulated signal and would eventually damage my aftermarket electric fan so I want to put the thermostat controller on that came with the fan and wire it directly to the battery......

I need to find the instructions to see if it mentions where, on the car, to tap in to auto kick on the fan when the a/c is turned on. But I wanted to ask here just in case it doesnt mention it or cant find them.


I search a little and didnt find it. If someone knows of a post please link to it here.

Thanks all.

[larryo340]

You might be able to tap into the A/C clutch turn-on and wire it to trigger a relay. It should have only a little draw on the A/C clutch.
Anybody else know?

[Breadfan]

You might be able to tap into the A/C clutch turn-on and wire it to trigger a relay. It should have only a little draw on the A/C clutch.
Anybody else know?

That's what I was thinking, unless there's another signal wire you can use.

An alternative is to put in a manual override switch and you can turn it on manually when you put the A/C on and also have manual override for hot days, track days, or traffic days or any time you want the fan on.

[Pops]

Todd I put in a over ride switch to the stock one using a relay on the GM.

[larryo340]

That's what I was thinking, unless there's another signal wire you can use.

An alternative is to put in a manual override switch and you can turn it on manually when you put the A/C on and also have manual override for hot days, track days, or traffic days or any time you want the fan on.

I like the addition of having a manual overide :)

[Tom Doan]

I have used the stock Bosch controller to run a Derel duel fan set up with no problems before. Now I am running a single Cobra fan with one relay coming off the AC clutch wire and one relay running off a dash switch. This has proved to be problematic, the Cobra fan draws lots of current and I have had to heavy up the ground to a braided wire then the main has been upped to 10 gauge and I carry spare relays at all times, they last 6 months. Tom

[Todd]

I like the manual override as well. As long as it isnt manual only.

I still havent looked for the instructions that came with the fan but will be doing that today.

[Breadfan]

Sounds like Tom has a good solution but may need to find a higher amp relay, what are the specs on the one you're using?

[Tom Doan]

I'm using the standard little black Bosch 30/40 amp relays with 5 male plugs on the bottom.

[Pops]

Thats what I used. No problems.