getting the heater back to working

[colonel mustard]

oh man, I could write a book on all the electrical crap the previous owner rigged up. I have been since then trying to sort them out one by one. so I'm ready to tackle the heating.

I have so many questions.

the truck originally came with AC. it is missing the compressor and some plumbing and I have zero desire to get it working again. that being said...does the AC NEED to work for the heat to work?

when I got the truck the heater was stuck on defrost and would not turn on. the lever on the control selector switch was broken so I replaced the whole temp control selector.

upon further inspection I noticed the previous owner used a jumper wire (which he used speaker wire wtf) at the blower motor terminal straight to a 12v source. it doesn't appear he bypassed anything....just added a hot wire. so one of the questions I have is why? what would that jumper wire be bypassing in order to make the blower motor stay on.

since I removed that makeshift wire 2 years ago (and have been living with out heat) I can not remember what 12v source it was hooked to. but I know it was an ignition source

 

[bucket]

The AC does not need to operate to have heat.

Usually when air only blows out the defogger vents, there's no vacuum supply to the HVAC vacuum switch.

If there was 12 volts run directly to the blower motor, that means everything was bypassed. The speed switch, the blower resistor, the high speed relay... All of it.

 

[Craig 85]

I'm currently working the HVAC on my '85. The PO had severed the vacuum line going through the firewall that operates all the vacuum pods for the blend doors. Here's a couple diagrams that may help you. The first one is for a TBI set up. Just focus on the bottom left for the under the hood portion. IIRC the '81 switch may operate a little different than mine, but I think the second diagram is for an '83 which should be the same as yours for under the dash.

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