So I've had this truck for 3 years. 1987 shortbed. Carbed 22R 4x4. As long as I've had it the heat has not worked. The air blows fine, but never warm at all. I just moved to the Chicago area and with the winters out here being what they are, I want heat!

There are no coolant leaks. Everything seems tight there. I'm fairly certain the heater core isn't leaking. I thought the controls on the inside might be the problem because they never seem to adjust right, so I manually moved the heater control valve under the hood all the way open and shut and everywhere in between. Still no heat.

Both of the hoses going into the heater core get nice and toasty. Is this indicating that it's flow through?

Any ideas on what to try next?

 

That makes me think the core is clogged or blocked maybe? I've never done it so I don't know how hard it would be but you might want to pull the core and take a look at it.

 

Flush the core out and see if that helps. You have two hoses coming from the heater core just flush it with water and when you fill the radiator back up to test it out open the hose up on the passenger side of the valve under the hood and let the air out.

 

Thanks for the advice. I just hooked up the garden hose to it and flushed it both ways. No blockage in there. It flows just fine.

Can I get a little more detail on letting the air out? While I was researching this I saw a few mentions for burping the lines. Where exactly should I open the hose? And at what point should I seal everything up?

 

make sure the air flow director in the dash is moving and directing the airflow correctly over the heater core. It could be stuck in the "vent" or cold position. You should hear it moving when you move the hot/cold slider.

 

That was my original thought. The sliders are shot. They move but I can only feel it actually move anything in about the last half inch. My thought was that moving the lever on the heater control valve would solve that problem and do the same thing manually. Was my assumption incorrect?

 

open the hose on the passenger side of the valve that is mounted to the fire wall. When all the air is out and just water comes out close the hose up. I kept the hose running inside the radiator. Some people say you can run it with the radiator cap off on a incline and the air will "burp" itself out of the system. Give it some time to warm up and you should be good to go.

 

that valve inside in engine bay only starts and stops coolant flow through the heater core, in no way does it direct heat over the core itself inside the cab.

if your sliders are shot then they are not moving that flapper under the dash.

 

All air in the climate control system first goes through the AC evaporator, and then the blend door controls how much of that air is then directed through the heater core before it goes into the mode door system (vent, floor, etc.). If the blend door is stuck closed, your AC should work fine and you should get no flow over your heater core. Our blend doors have mechanical armature linking them to the knob. Carefully remove the blend controls from the dash and trace the armature back to the blend door. There is usually an adjuster on mechanical linkage like that, but I've never seen our 4runner's in person. That's one of the parts that a layman will often bend or break when trying to remove part of their dashboard.

As far as the burping of the radiator goes, yes. You absolutely do need to burp your system if, especially if you worked on your heater core. You don't even need an incline for our particular vehicle. The FSM states that 'no special procedures are required', just leave the radiator cap off and run the engine for 5-10 minutes until the air bubbles top coming out. If you don't burp it and fix the blend door, the air in the system will make it ineffective and the air will prevent the system from properly pressurizing keeping the boiling point of your coolant too low.

 

Not sure if you are having the same problem but my tacoma heat adjuster on the dash was stuck. when I tried to change to heat all I would hear was a click, click. I replaced the wole unit and in the process found that the cable going to heat door on firewall was caked with dirt/gunk. $11 dollar cable and problem was solved. Not sure if its the same system on the different trucks but might be something to check.

 

If all else fails, heatercore time. I just did mine it wasn't that bad of a job and now my truck has tones of heat