Need Advice on Heating/Cooling Wiring

Hey guys...been a minute since I've been on here. Took a break from the Texas heat but now that it's cooled down I've started working on the truck again. I think it has been determined from the last pics I posted that the truck came with just stock heat & then dealer air was added after the fact.

My issue is I am getting air to blow when the switch is on A/C, Heat, & Defrost & fan speeds work so that seems to be OK but I am not getting any hot air...just blows cold. I noticed that the cool/warm slider has no resistance so that cable to the door must not be hooked up. I am getting ready to pull the switch to see if there is a cable is there but just disconnected.

My other issue is I'm really wondering about some of this wiring. In this pic I am not understanding why this plug is not hooked up to anything, any suggestions on what this actually goes to?



Here I am assuming the red & orange wires hook together and the black goes to the ground on the blower switch terminal.



Next thing I am not understanding is why one of the blue wires is cut on this fuse block.



And lastly...these two black & gray wires were just disconnected, do you think they just connect to each other? Not sure what they are for.




Any help would be greatly appreciated. Sucks not having heat in this colder weather & I really need the defroster to blow hot to keep my windshield from fogging up or to de-ice.

There could be several reasons for not getting hot air, and a biggee is if there's no cable of if it isn't connected.  Others would include a plugged heater core, a valve in the heater hose, or if you don't have a thermostat.

On the questions about wiring, if the heater seems to function properly the way it is then I wouldn't think those connections go to the heater or blower.  Perhaps to the A/C system?

Can you tell where the wires from the 5-terminal connector go?

On the red, orange, and black wires, did you disconnect them from the blower switch?  I'm not sure how the switch could work if it is supposed to have those wires.

As for the blue wire that is cut, w/o knowing what that fuse goes to it is really hard to tell.  Can you trace the wire back to something?

And the two-wire connectors appear to be made for each other, but I wouldn't go plugging things together just because it looks like they should be connected.  Perhaps they were disconnected for a reason?  What doesn't work?

emunder wrote

....any suggestions on what this actually goes to?

That looks like the plug for the Multifunction Warning Buzzer that lives above the glovebox (Or used to live above the glovebox). I don't know what happens if you disconnect it...probably nothing other than the buzzer doesn't work. Is there a buzzer that goes off in your truck while the Fasten Seatbelt light is on (When you first get in and turn the ignition on).

emunder wrote

Yeah the cable that goes to the back of the cool/warm lever switch was not connected and it's broken. Doesn't have the metal lead coming out of the plastic cable shield to hook up to the switch so I'm going to have to replace that cable that opens & closes the heater core door.

I hear ya on the red/orange black wires. The black wire was plugged into the blower as a ground if I remember correctly & orange & red plugged together. I am getting air blowing when I plug all that back together.

Have no idea on that fuse block, guess I'm going to do what you said & see if I can trace it back to see where it's going.

Thx for the help Gary.

Thanks sir...I will go and see if there is a plug up there to attach that to. Maybe someone unplugged it so the warning buzzer would not go off.

emunder wrote

Thanks sir...I will go and see if there is a plug up there to attach that to. Maybe someone unplugged it so the warning buzzer would not go off.

I'm going by memory here, but mine is mounted above the glove box. If you have AC, it would be mounted between the two vents on the passenger side. Mine is a white plastic module...maybe 3" long by 1.5" x 1.5" or so. I haven't been in there in a little while, but that is what I have in my memory...lol. I did take a picture of it, but I can't find it now. Perhaps it was disconnected when the dealer AC was installed.

Thanks I appreciate it. I looked but could not find anything that resembles this. I will take a look again & see if I missed something.

On another note...I put everything back together & manually opened the door for the heater core inside the engine bay & bam...heat is hot as hell lol. Wish I would have done that to begin with but at least I know the cable is broken so at some point I can replace it. It'll work for now though now that it's cold out.  

Good work!  Now you know the problem, and have a temporary solution.  Well done!

Yesssir!