Logic/Assumptions correct?

[Lt46]

A little background; I've added a 12v fan in front of my tranny cooler, controled by a lighted, 12v switch installed on my dash. Reason was to have the ability to switch on the fan when in heavy traffic or other low airflow situations, adding to the cooling effect on the tranny fluid.

The problem; I've had to replace the lighted, dash switch twice in 6 months due to the light burning out.

The common denominator to these burnouts is that I was testing the fan operation while parked, hooked up to 110v.

My assumption is and a guess at this point; during each event, my PD 9245 converter was in boost mode (14.7v), with the extra voltage, my Trik-l-Start ramped up charging the chassis battery. Since my 12v fan switch is wired hot to the battery, this extra voltage fried the bulb when I turned the fan on while testing.

Does this logic make sense to anyone? I'm open to suggestions for curing this reoccuring problem. Thanks.

[Fossilhog]

Quote:

Originally Posted by Lt46 A little background; I've added a 12v fan in front of my tranny cooler, controled by a lighted, 12v switch installed on my dash. Reason was to have the ability to switch on the fan when in heavy traffic or other low airflow situations, adding to the cooling effect on the tranny fluid. The problem; I've had to replace the lighted, dash switch twice in 6 months due to the light burning out. The common denominator to these burnouts is that I was testing the fan operation while parked, hooked up to 110v. My assumption is and a guess at this point; during each event, my PD 9245 converter was in boost mode (14.7v), with the extra voltage, my Trik-l-Start ramped up charging the chassis battery. Since my 12v fan switch is wired hot to the battery, this extra voltage fried the bulb when I turned the fan on while testing. Does this logic make sense to anyone? I'm open to suggestions for curing this reoccuring problem. Thanks.

Not really, if your engine was running wouldn't your alternator be putting out 14.7 volts?

[Lt46]

Fossil,
Yup, you're right! OK, that shoots down my previous assumption. Maybe these cheap, made in china, switches are the problem. Like I said, I'm guessing as to why these lighted switches are blowing. Hmmm, time to rethink this whole thing.

[Gary RVRoamer]

I've had numerous failures of those crappy lighted switches too. Went back to good old chrome plated, unlighted toggle switches. I put a separate indicator light on them (any Radio Shack has 12v lamps or LEDs) if I need a light.

[Fossilhog]

Quote:

Originally Posted by Lt46 Fossil, Yup, you're right! OK, that shoots down my previous assumption. Maybe these cheap, made in china, switches are the problem. Like I said, I'm guessing as to why these lighted switches are blowing. Hmmm, time to rethink this whole thing.

Is this switch an inline feed to the fan motor or do you have a relay? I have a mini lighted switch that energizes a relay for my fog lights. If it was an inline feed there would be too much amperage for the filimant, maybe, ya thiinK?

[Lt46]

Quote:

Originally Posted by Fossilhog Is this switch an inline feed to the fan motor or do you have a relay? I have a mini lighted switch that energizes a relay for my fog lights. If it was an inline feed there would be too much amperage for the filimant, maybe, ya thiinK?

This is an inline feed to the fan motor, no relay in play. From battery to switch with a 20 amp fuse in between. If I knew how to wire in a relay, I'd do that, but I'm not good at this type of work. Thanks.

[Mothership]

You might need to install a relay between the fan and the lighted switch. Fans, because being motor driven pull a lot of amps. As the motors get older and dirtier around the armature they will also pull more amps. You can install a 20 or 30 amp relay so most of the power is going through the relay and not through the switch. I hope this helps!

[Mothership]

Sorry...I just re-read Fossilhog and your last posts. You are on the right track with the relay.

[Clay L]

You can get a small Bosch 20 amp relay at most auto stores.
Just wire the switch to activate the relay instead of the fan and wire the relay to turn on the fan. The relay contacts are wired like the switch was.

One side of the relay coil goes to the dash switch, the other side goes to ground.
The armature (movable contact) of the relay goes to 12 volts and the normally open contact goes to the fan.

[Lt46]

Quote:

Originally Posted by Clay L You can get a small Bosch 20 amp relay at most auto stores. Just wire the switch to activate the relay instead of the fan and wire the relay to turn on the fan. The relay contacts are wired like the switch was. One side of the relay coil goes to the dash switch, the other side goes to ground. The armature (movable contact) of the relay goes to 12 volts and the normally open contact goes to the fan.

Perfect! Thanks for that info Clay L.

[porscheracer]

20A relay?? You can get an old Ford starter solenoid that's good for about 125A for less than $15 . . . might not be rated for constant duty, though.

[J Walker]

Your Progressive Dynamics has a max voltage of 14.4V. Is the light on the switch on only when the fan is on. It seems that when the converter is running the fan is off and the light it off. Alternators put out a little over 14V usually. Could just be a cheap light in the rocker switch.