The heat only seems to work on the defrost and heat setting which is floorboard heat. And even then it barely does anything. Only cold air comes out on vent setting. What should i Check?

 

If you are trying to get heat out of the vents on each side of the dash, that will never happen. The vents on each side of the dash are ONLY connected to outside air. If you are not getting hot air, check the heater valve on the firewall to see if the cable is opening it fully, your heater core could also be stopped up. I have a 1980 4X4 and I just had to clean my heater core out recently. You can do that by removing the heater hoses from the valve and connecting a garden hose to one side of the valve and running tap water through the core.

 

It's also pretty easy to replace the heater core on these trucks.

But yeah, check the valve first. Just on the engine side of the firewall, right around the middle.

 

I know the outside vents are connected to outside air. I was talking about the vents below the radio and what not. Its weird because i can feel heat when its on defrost and heat setting but not on vent at all. Although the defrost puts out good heat it barely blows hard enough to defrost the windshield at all. But i will check the valve and ill flush the heater core and see what happens

 

You might want to check the doors that direct the flow of air to see if they are shutting/opening all the way. Unlike most vehicles where those doors are vaccum operated, yours are cable operated. The fresh air vents could also have allowed leaves or other debris into the system that is blocking the air flow.

 

Alright ill check that also

 

The heat in these trucks is not good. I had it down at one point...by sold my 83 a few years ago now and so it's fading.

I think I only remember getting heat on two different settings. I know some people block off those lower, middle vents and put their stereo there, if that tells you how useful they thought it was for heat...

It sounds like your issue is more likely a dying or somehow restricted fan or ducting, not actual heat.

 

So your heat never worked on the vent setting?

 

I don't really think it did...

But I'm fairly sure heat only came out of those center vents on one setting, if any...But like I said, I don't really remember now.

What I do remember is that my heat worked, and I could get my cab warm, and windshield defrosted. So you've definitely got something going on.

But about once or twice a year someone who bought a 79-83 truck for the first time comes here and posts wondering why their heat doesn't work, and about half the time, it works fine. Just not like they expected it to.

I'm thinking it's a little of both with you. You expected more out of it than it ever had to offer, but it's also not working quite right.

 

The "vent" position that directs airflow to the facevents (those on the sides of the dash, and those right under the radio) bypasses the heatercore altogether; they never blow hot air unless that's what's outside. Toyota called this "Flo-Thru" climate control, or something like that. As far as I can tell, it was an 80's fad to allow heat to your feet and cold air to your face to keep you awake. A worthless gimmick if you ask me, but your only solution is to modify the HVAC manifold. I'm working on an easily replicated way to modify it like that, albeit "on the back burner". It might be as simple as gluing in a plastic plate perpendicular to the heater core, forcing all air through it.

It's hard to quantify, but to me, the heater output of my '81 feels more than enough to heat what is one of the world's smallest truck cabs. If yours is weak, then either there's not enough hot coolant flowing through the heatercore (either clogged core itself, or a malfunctioning heater valve), or there's debris blocking airflow through the heatercore, or you're at McMurdo station down in Antarctica and need to adjust your expectations accordingly

 

Quite possible truck this old dirt blocking the outside of the heater core so little heat gets out of the core into the truck.

The heater core can be blocked inside from not changing coolant when needed.

Blockages from what ever in the duct work not allowing air to get where it needs to go.

In any of my Toyota`s I only use the defrost setting in the winter.

Also to get the best heat the control should be set to fresh air.

Check the easy first that the heater control valve is working like it should.

 

McMurdo!