No Heat!!

[slugboat]

Hey there guys, I recently bought a 85 nissan pickup 4x4. The truck runs great except I have no heat. When I am driving , only cold air ( since it is the winter ) comes through the vents. I thought this might be a sign of something. Shouldnt I at least get warm air through the vents once the engine warms up? I cant get the blower fan to turn on either, but I thought I should feel SOME heat. Any advice would be greatly appreciated. Thanks folks!

[PapaSmurf2k3]

You should start by making sure no one bypassed the heater core for some reason. On the firewall under the engine bay, there should be 2 hoses going from the engine to some ports on the firewall. If they just loop back to the engine, it has been bypassed.
The other option is that the heater control valve itself is broken. Basically it regulates flow through the heater core. I don't know what the ones on your vehicle look like, but you can try getting someone to operate the "cold to hot" thing inside the car to see if the valve moves. If not, then there might be a cable broken.
Then you can flip it by hand, like I do!!

[slugboat]

I will try that and let you know! I should just be able to take off the housing for the switches to see the cable, am I correct?

[PapaSmurf2k3]

I'd try and locate the actual heater control valve first. It might be in the manual or factory service manual if we have one uploaded (check through my signature). Then have someone move it back and forth inside the cab and see if you can see the valve opening/closing under the hood.

[slugboat]

You have no idea how much help you have been. I will try this soon as possible. The hoses that run to the heater core have not been bypassed, but it is possible somebody threw some bolts in there and clamped them off. I will try to figure this out by the end of the day.Thanks again papasmurf!

[PapaSmurf2k3]

No problem! It wouldn't hurt to remove the hoses and say,put a garden hose through one on the firewall to make sure you have flow through the heater core (clear water should come out of the other port).

[slugboat]

I think I have narrowed it down the either the fuse port, or a faulty fan. I took out the blower fan , it didn't have anything in it. I also checked all the visible connections. There is a fuse missing where I think it would control the fan, but that same port seems to be broken. Is there an easy way to bypass that? I am not 100% positive, but I am pretty sure I found the temperature control valve. It was under the dash on the passenger side, pretty close to the control station ( about as far left of the passenger side as it could be ). Also when I open up the vent and touch the heater core, it is warm, but I feel like it should be almost too hot to touch. The hoses running to it inside the cab get almost to hot to touch, so I don't think they are blocked off under the hood.
If I were to run water through the hose, were exactly would it come out, and would it harm anything? Is there anything I should remove before I do this? These are all my questions for now. Thanks again, I feel like I am pretty close to fixing it, but I couldn't have done it without you. Hope to hear back from you soon!

[PapaSmurf2k3]

Ah ok, so it sounds like you ARE getting coolant flow through the heater core, and now you just need airflow?

If your fan is broken, you should be able to flip the intake method from "recirculate" to "fresh air" on the dash and force air through it while driving at higher speeds (like 50+).

[slugboat]

Ok, When I get the engine warm enough I can flip it to " Bi- Level " to open up the vent near the floor. When I do this I get heat out of that port, but that is it. Even if i close that and get up to 50 + , I still only get cold air out of the vents on the dash. I get nothing out of the defrost vents. Does this mean something is clogged, or is there another vent I need to open or close?

[PapaSmurf2k3]

It almost sounds like your diverter isn't functioning. Basically it is what sends air to the different zones of the cabin (you know, change from defrost, to feet, to chest). Could be clogged, or it could be something in there actually broken. I'm not familiar enough with your vehicle platform to tell you for sure though. Either way it sounds like you're going to have to dig a bit!