Blower Motor Relay

Blower Motor Relay - 08/05/08 07:11 PM

Has anybody wired a relay into their blower motor circuit to get more voltage from the high fan position of the switch?

I'm thinking a relay mounted near the fan, pulling voltage directly from the alternator, with the normally closed position feeding the voltage from the resistor to the switch and the normally open position feeding alternator output directly to the fan would work. I think I'd just have to route a wire from the switch to the relay trigger wire to do this.

See drawing (sorry for it being so crude).

Any comments?

Attached File

4599916-Blower.bmp (109 downloads)

Posted By: 1_WILD_RT

Re: Blower Motor Relay - 08/05/08 07:15 PM

I've done quite a few blower relay upgrades on mopars, helps more than you would think..I typically grab power from the battery stud on the starter...

Posted By: NotEnufGarage

Re: Blower Motor Relay - 08/05/08 09:04 PM

Quote:

I've done quite a few blower relay upgrades on mopars, helps more than you would think..I typically grab power from the battery stud on the starter...

Is my drawing similar to the way you did it, or did I miss soething?

Posted By: Anonymous

Re: Blower Motor Relay - 08/05/08 09:34 PM

I added them for my blower because the wire that feeds it that runs up the steering column got very hot as well as melted the fuse holder. This was in my 76 Duster. Works well.

Posted By: 1_WILD_RT

Re: Blower Motor Relay - 08/05/08 09:38 PM

Same idea, I just don't like using the alt stud, not that threres anything wrong with it I just find the starter stud is more inconspicuous & is directly connected to the battery with a really big wire...

Posted By: Anonymous

Re: Blower Motor Relay - 08/05/08 11:13 PM

Quote:

Same idea, I just don't like using the alt stud, not that threres anything wrong with it I just find the starter stud is more inconspicuous & is directly connected to the battery with a really big wire...

The thing about using the alternator stud is, the alternator wire isn't all that big, usually, and your relay connection would be fine IF you only ran the fan with the engine running. However, with the key off, all that current has to come through from the battery end, down the alternator wire, through the fuse link, etc. If you start adding other junk at this same point, it won't be long before it's overloaded.

I say, hook it to a "main" battery connection.

Posted By: NotEnufGarage

Re: Blower Motor Relay - 08/06/08 02:56 PM

I forgot to mention, I've upgraded the alternator to battery circuit to 8 gauge wire. Also, this is in a diesel truck, so the starter lug is huge. Not sure I could find a connector to fit it.

Posted By: NotEnufGarage

Re: Blower Motor Relay - 08/07/08 04:19 AM

Well, it won't work the way I thought it would.

I think I'll have to wire in a separate switch to trigger the relay, kind of a "turbo blower" option... With the switch off, the voltage from the regular switch will pass through, with it on, direct battery voltage, without the losses from the ignition switch, resistor and fan switch.

Posted By: NachoRT74

Re: Blower Motor Relay - 08/07/08 06:51 AM

I used 4 relays, three of them one for each speed, just before the resistor... the 4th one, at the MAX speed output from control