OH sorry stupid me...... I just looked at post directly above mine and there is the answer.

 

9297oldram over on cumminsforum sent me here. Great thread.

I'm with Jim on being addicted to relays. My hand fired wood boiler control set looks like past era pinball machine guts.

I'm going to try to configure it so the only power going through the ignition system is relay coil current. Best guess is it'll take 4 relays.

Bought some relays and sockets off'n eBay. Contact wires mic'd to 17 G, (32/32 tinned no less). I can use them for lighting in trailer wiring. I found some Tyco sockets and terminals for mini-ISO relays, and by back treading on the recommended terminals and finding the line spec sheet, I found some 10G terminals that should work. Parts are coming. I Also ordered sockets and relays for 70 amp maxi-ISO. Terminals are available up to 7G.

I'll post what I find out when I get the parts.

What's a good source for primary wire in 100' rolls.

 

First thanks for your post as it has shown me what was wrong with my blower high speed. Now on a second note does anyone know where I can buy new vent diverters? One of mine has no guts left in it and that big hole just drives me nuts to look at it on my vent.

 

hello all, I just did this and works GREAT!! However, have a small problem.....when I push the off button with it on high, it still stays on, ac compressor and all!. If I switch it down 1 notch on the fan, it will shut off and stay off. I "think" somehow its like getting a power surge somehow...any suggestions?

 

Rockauto has the part for that 75amp relay;

http://www.rockauto.com/dbphp/x,cata...332002150.html

 

So change to a 75 amp relay?

 

Anyone?...could really use some help.One of the relays is getting hot, to hot I think to soon....like after about 5 minutes of being on

 

This is one of the reason that I used the 75-amp power relay to switch full power the blower motor, I was afraid when the circuit breaks that they would arc excessively and cause the relay to possibly stick in the on position and cause a fire, the power relay has 2 contacts inside to help suppress the arc.
also my small relay got too hot to my liking after a few minuets of operation even though the motor runs below the rated capacity of the relay, when it first starts it can easily draw more than 40-amps for a brief time.
My 75-amp relay don't even get warm.

Note, the blower not turning off while on high speed is a known issue that I have to work out, it is due to the motor generating its own voltage and latching the relay coil on, you only need to drop it down 1 click and it will shut off normally, besides after you have done this modification you won't always have it on Hi speed because it will blow you out of the truck.

Jim

 

I don't think it's a motor auto generating issue. If you look closely at your diagrams, you'll find you are back feeding the control side through the resistor pack.

 

Ok Jim,so yours does that?Like it wont shut off onhigh?Thought I wired something up wrong.
So should I switch both relays to a 75 amp or just the one that is getting hot?Might as welldo both of them.
Also noticed my ground was getting warm,but havent upgraded the ground like you said do yet...

 

No, you only need to replace Relay K-2 with the larger 75-amp Power Relay, Relay K-1 is only to break the coil circuit and only has to switch milliamperes of current, replacing it would be a waste of money, you will need it for other projects.

You need to upgrade your ground wire for this to work properly or you could burn up your ground wire.

Give me a few days until I get my truck back from the transmission shop, I have some revisions but I have to try it on my truck first.

All of the extra airflow is nice to have especially at first but now when I run my A/C I will cool down the truck and the drop the blower down 1 notch to MED because after awhile the sound of the air blasting away at you is exhausting like hanging your head out of the window, my passengers sometimes start to drool.

Jim

 

sorry if this question might have been asked already but has anyone though about running a wire from the blower motor resister, through firewall, straight to the blower motor similar to the relay idea? i figure it could cut down on the power loss though the 8 feet of wire and couple connectors that is has to travel though to get to its destination.

 

Jim hope you got your tranny fixed !Any more progress on revisions? I started to install but have a ????
In the very begining of the write up you replaced the green wire to the selector switch(fan high speed)with a 12 ga. piece apprx. 5 feet long then drilled a hole by vacumn lines on engine side of fire wall and ran wire to engine bay.I got lost here ,you started talking about where to mount relays. and I could not find where you mention to connect the 12 ga. wire you passed through the fire wall.If I understood relays better this is probably evident where to connect but i dont so please help.
I have read entire post several times and see refrences to several wire sizes and connections to relays but I dont see the 12 ga. wire. Iam thinking you splice this to the fan with lead from #87 on K-2 but not 100% sure a

 

Just realised you can zoom the wire diagrams understand now the new wire from fan switch to K-1 #30 is a 12 ga.wire you originally installed in the begining of the post that went through fire wall by vacumn lines.
Unless Iam wrong aout this ! Where i got confused is later in the post where you get specific on relay connections K-1 #30 calls for 14 ga. wire,is this a typo or is 14 ga. sufficient? Or am I still not getting this? Like I said earlier probably wouldnt be so difficult if I understood relays better I just want to be sure on this before i button everything up.

build it like the picture
sometimes a picture is worth a 1000 words

 

I was looking at my blower motor the other day, there is two wires that drive it, a positive and a ground. Why not just splice that and hook a relay to that? As my understanding a relay is to take a small amount of power and stabilizes it.

In theory if you get a 75amp five prong relay(or double), power the 86 and 85 prongs (only can go one way) and from 30 to 87 out to the blower motor.

Would that be a simple solution?