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Discussion Starter #1
1991 B150 Van, 5.2L V8

My heater system Had a burnt switch and wire terminal. I guess it happens when ran on high a lot. Once I saw it had 5 vacuum lines, 3 vacuum devices, 12 wires, and A/C buttons I can't use I felt a case of OCD. I just need to turn it on/off! I don't need cold. For cold, we'll open a window. Just on/off.

I fully removed all the vacuum lines and removed the old panel. So, I'm basically starting from scratch. New blower, Wheel, Switch, Heater Resistor. and a panel I made to mount switches and things.

I'll burn up a plain old switch since it will run at max speed. So, I need a blower resistor. I can't find a pin-out for one (mine). How do I do this?

Thanks.
 

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If you want on/off control with no regard to speed, you don't need a resistor, but you will need a relay.
 

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Is that so the switch can move a little current to the relay so that relay can move a lot to the blower?

Can you help recommend a relay that can handle the high current for prolonged periods?

I've read Conflicting posts about whether the resistor is or isn't used when on high. I'm worried if power totally bypasses the resistor, the blower may burn up.
 

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Yes, exactly.

You need a relay rated for the same load as the original blower motor fuse. My guess is 25 or 30 amps. The 4 or 5 pin relays commonly found on the shelves of most parts stores will work fine.

A resistor is only used for lower speeds. A relay is used and the resistor is bypassed for wide open operation.
 

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Yes, exactly.

You need a relay rated for the same load as the original blower motor fuse. My guess is 25 or 30 amps. The 4 or 5 pin relays commonly found on the shelves of most parts stores will work fine.

A resistor is only used for lower speeds. A relay is used and the resistor is bypassed for wide open operation.
I bought a 30 amp relay and switch. I see how to hookup the relay, but am curious how much current will pass between battery/switch/relay as there's no resistor.
 
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