Workhouse Radiator Thermo Switch

[flash1942]

Two years ago,there was a discussion here about wiring a switch to make the radiator cooling fans run. It said the thermo switch on the radiator provides a path to ground, so a switch wired to ground would make the fans run.This is easier than wiring a switch,fuse and relay from a 12v source. However, I have looked high and low and I cannot find the thermo switch on my 2002 w22 Workhorse. Can anyone give me a good description of where it is located? Thanks,Lloyd

[Full-Timers]

It’s not that simple. The PCM provides ground for the Aux Fan Relay, which provides power to the Aux Fans through its contacts. The relay is in the fuse box under the hood along with Fuse #29 (relay power (lables Stop/Haz)) and Fuse #33 (Aux fan power).

[DriVer]

Quote:

Originally Posted by flash1942 Two years ago,there was a discussion here about wiring a switch to make the radiator cooling fans run.

Lloyd, Is there a great reason why you need to manually turn on the auxiliary fans?

[flash1942]

No,not really.I guess I have too much time on my hands. Every time I read an improvement on this site, I want to do it.I am now going from Houston to Seattle and I thought this might be useful in the mountains. I believe my fan clutch is working properly, coolant has been changed, new radiator cap, and air dam is now repaired. From Houston to Las Cruces,NM, the Scangauge shows radiator temp to be OK. So I really don't have a problem. However,2 years ago Max49 added a switch and had pictures on this forum. The pictures are no longer available. Thanks, Lloyd

[BellaBo]

Quote "Lloyd, Is there a great reason why you need to manually turn on the auxiliary fans?"

I could see where it would help cool down the system and engine after shutdown a little faster. I would think you would want a timer though in case you forgot to turn them off.

It also may help keep the big aux fan from coming on too soon, if they were turned on approaching a hill, saving a little horsepower for the climb.

[max49]

It's very simple. I just tied into another 12 volt source and ran it to the switch and tapped into the power wire for the fan. It still comes on automaticaly but I can turn it on in advance of a long mountain pull or if I'm sitting in a traffic jam before the temp. rises to activate it automaticaly. I've had it for a couple of years now and it has not given me any negative affects and if I don't want to or forget to use it, every thing works the way WH designed it to. I can't find the pic of where I tied into the power but it's over by the engine fuse box. I also put an inline 20 amp fuse in.

The green indicator light comes on when I turn the switch on, or if it comes on automaticaly so it's easy to monitor if it is working and on.

[oemtech]

Add the Oemy's Fan Switch Mod

[max49]

As we have come to expect from you Dale, another good and helpful addition to your site, for us.
I've never really understood how relays work but I haven't had any trouble with my fan switch yet.
I had the shop install the ignition switch relay mod, per your instructions while they were fixing my tail/ clearance light issue. Turned out to be a bad ICC switch.