I was talking with a alarm installer and asked him if they sold 70 or 90 amp relays so that I could wire up my electric fan on the "high" side with a manual switch. He said he never heard of anything that big and that they sold a 40A/60A relay. He then said why don't I use a starter solenoid? I never thought of using one and I know it definately would be able to handle the amps that the fan would draw. My concern would be I'm not sure of the duty cycle of starter solenoids. I know they draw a lot of amps for a short period of time, but the way I would wire it would draw a small amount of amps (30 or 40 vs 600 or so when starting the truck) but would be on for a longer period of time (10-15 minutes vs a couple seconds). I will only be using the "High" speed mode when I tow going up mountains in my area, so if additional cooling is needed for some reason. So basically the "high" speed side is used a couple times a year. The "low" speed side is wired to temp probe in the radiator which is the main cooling control.

Let me know what you think.

 

DQ05, Why do you think you need a relay beyond a std 40? This is interesting. How large is this fan and where is it going? Well anyway, if push comes to shove, wire two 40s in parallel and if you can't find a riding lawn tractor starter-noid. Then you'll need a relay to keep it energized.

 

I've bypassed p/w heater fan and stereo due to wiring problems. just power from ignition switch to activate it and power straight from the battery to power the stuff. It is activated when the truck is started an stays on until I turn it off and have had no problems in the last 8months

 

std 40 fuse will work just fine all others are overkill if something happens to the fan you will never no with the 70's

 

dodgequad here is a link to where I ordered the 75 amp relay I used http://order.waytekwire.com/productd...POWER%20RELAY/

 

Depending on what fan you use. The high speed Ford Taurus and Mark VIII fans draw over 42 amps on high. Make sure your wiring is large enough as well.

 

Yes, I want to wire up the "high" side of my taurus fan which would destroy that 40Amp fuse. So I need something a little beefier to ensure it won't blow. I checked that link and how do you know the Amp rating on the Relay?

 

I know it's a 75 amp b/c I was looking for a bosch 75 amp relay by part number and it cross referenced that relay. I think they stopped making the bosch one, you can look for yourself in the catalog for that site to verify it's a 75 amp http://www.nxtbook.com/nxtbooks/waytek/catalog/ just search for relay and then match the part #'s. I've been running my taurus fan on high w/ it for awhile now using the wiring shown here http://www.fordmuscle.com/archives/2...cfan/index.php

 

Napa part number or reference number ST-35. Don't know the amperage rating but its used for glow plugs or a starter relay in something and is a continuous duty relay with bolt on terminals. I use it for the manual switch on the high speed setting of my E-fan. I also use one for the power supply on ALL of my ignition switched accessories. Its a beast and is about the size of half a redbull can.

Looks kinda like this one pictured but is rated for continuous duty and cost like $60.00.
http://www.napaonline.com/MasterPage...olenoid+Switch