Hayden fan relay with Mark 8 fan

281pony

Active Member
Aug 31, 2003
2,681
2
46
Oly, WA
i just purchased an adjustable hayden fan relay from cut rate today. my mark 8 fan is currently wired so its always running. im doing some research on this controller, and im seeing an issue.

i stumbled upon someone saying the mark 8 fan, draws 90 amps at initial start up. this thing has an inline 25 amp fuse. is anyone running this combo? so do i just need to buy and splice in a larger inline fuse? :shrug: it is doing fine now on my 30 amp hvac control fuse now.

actually, is there a better suited controller i can get at cut rate? p/n on the controller is 4003647-01. it uses a probe into the radiator fins, i have transmission cooler provisions on my radiator, i was hoping to use one of them if it helps accuracy.
 
I don't know how you've been running high speed off the HVAC circuit/fuse.

If you do not already have one, you should be running a 75 amp relay for that fan.

You could use a tapped t-stat housing for a threaded sender if you decide to go that route. You cannot use the trans's heat exchanger fittings.
 
I don't know how you've been running high speed off the HVAC circuit/fuse.

If you do not already have one, you should be running a 75 amp relay for that fan.

You could use a tapped t-stat housing for a threaded sender if you decide to go that route. You cannot use the trans's heat exchanger fittings.

Yeah the Hayden controller will not work, it will smoke the relay as soon as the power goes through it. The fans pull 55+ amps, I also install the 75amp relay and that set-up works very well, make sure you use the proper size wire also.
 
i got the car this way. its just wired to ignition power i guess. there is no relay at all right now.

so your saying to wire in the hayden and get a 75 amp inline fuse inplace of the 25 it has now correct? or get a whole new controller all together?
 
i got the car this way. its just wired to ignition power i guess. there is no relay at all right now.

so your saying to wire in the hayden and get a 75 amp inline fuse inplace of the 25 it has now correct? or get a whole new controller all together?

You would not want to replace any fuses on the controller - the controller, wiring gauge and fuse are all chosen to work together.

You could use the controller as it comes. But instead of running the output wire from the controller to the fan's + motor lead, you would use that as an input to your Bosch 75 amp relay. Basically the controller's relay would become a slave relay to the Bosch relay (kinda like how your fender starter solenoid becomes a slave to a piggyback solenoid when you install a newer starter in an early aero fox).
 
gotcha.. i hate electrical as you know. so im going to look for a better controller to just drop in. i think i saw a hayden part number listed by jrichker for a "recommended" one. ill just go in with that and see where it gets me.
 
If you can wait, get a Delta Controller. It's the best out there and easiest to wire up. It just takes awhile from when you order it to when you receive it.

If you want to do a conventional controller, make a price list to see what it will cost with every little part. It might be pretty close to the cost of the Delta unit.