Hvac headunit wont turn off

[Skolman91]

Just finished my swap, once you turn the key on the hvac powers up and the temp hot/cold slider stays lit when key off. If i hit a action button (vent,a/c,defrost) you can hear it start the action then the head unit goes off like it should.
Ive deleted a bunch of wiring during the swap, im kinda curious if maybe it doesnt have enough resistance or load on it after deleting almost everything that it doesnt shut off.
Anyone on here have some in depth experience with something like this or something similar, that wont just say these things go weird replace it..?

As im writing this i rem i should prob check the wiring diagram, but everything works correct, it just wont shut off..

 

[Orpedcrow]

What year? What swap? Factory a/c?

If I remember correctly, in my 97 there’s a harness on the passenger side coming from the HVAC box into the engine bay.

It’s possible that you’ve got a relay sticking/latching, sometimes that happens when they are going out and sometimes if they have more than their rated current running through them. (The thin metal tabs inside that do the switching will sort of weld together)

Just stuff to look at…

 

[Skolman91]

What year? What swap? Factory a/c?

If I remember correctly, in my 97 there’s a harness on the passenger side coming from the HVAC box into the engine bay.

It’s possible that you’ve got a relay sticking/latching, sometimes that happens when they are going out and sometimes if they have more than their rated current running through them. (The thin metal tabs inside that do the switching will sort of weld together)

Just stuff to look at…

90, ls swap, no ac at all anymore.
I will check but i dont rem seeing a relay for the hvac headunit

 

[Erik the Awful]

I will check but i dont rem seeing a relay for the hvac headunit

I don't know if it's the same on the later trucks, but on the early trucks there are three relays on a bracket on top of the HVAC assembly. You can likely access them through the glovebox.

 

[Skolman91]

I don't know if it's the same on the later trucks, but on the early trucks there are three relays on a bracket on top of the HVAC assembly. You can likely access them through the glovebox.

Those are blower relays and ac compressor relay iirc

 

[Orpedcrow]

Did you pull the unused wires out at the plugs? Or cut and tucked them taped? I’ve seen cut wires touch each other at the ends, the insulation will shrink sometimes or if two wire got cut at the same time with dull cutters the copper from both wires will squish together.

If the older hvac controllers are like the newer ones than it could be dry rotted and the case falling apart and there could be metal touching or a random wire touching the circuit board in the dash. (I’ve got my entire controller wrapped in electrical tape because I’m too cheap to replace something that works lol)

 

[Skolman91]

Up top,
also started thinking and the interior lights dont work, would a door switch have any effect on turning off the hvac?