2nd Gen heater

[LaOutbackTrail]

Hey guys,

I know a couple of us have had this issue, has anyone found the reason why their trucks are not getting any heat in the cabin?

My guesses are heater core or the mixing flaps for the heat.

At this point I have zero heat, winter is coming up and we still have some adventuring to do.

 

[eurosonic]

Well I realized why mine wasn't working.
Kind of embarrassing to admit it. When my mechanic was doing the timing belt job, coolant flush etc. he noticed that my heater core was leaking. It was a hot summer, so he bypassed it completely by connecting the in-line back to the engine. And kind of forgot to tell me. :]
I find out on accident by browsing under the hood when running the wiring for the spot lights.

So yeah, have to connected back bc it's getting chilly here at night.

 

[scrubber3]

I've still not figured mine out. It works halfway on the driver side, but nil on the passenger side. Install a 12v aux heater to make up the difference. Works well enough. I'm sure the heater core is corroded internally and a flush only works for a day or two because of it. It works good enough for me as I don't mind the cold all that much.

 

[off-roader]

What position are your fresh/recirc vent controls in? Iirc when in the wrong position one side will have cold air.
EDIT Sorry 'bout any confussion but I was finally able to check it this morning and it's the passenger side that gets cold when the center dash slider is in the wrong side.

 

[Justice R]

Same issue with my 99. Weak heat on drivers side only. Going to try reverse flushing the heater core and see if that helps.

 

[scrubber3]

What position are your fresh/recirc vent controls in? Iirc when in the wrong position one side will have cold air.
EDIT Sorry 'bout any confussion but I was finally able to check it this morning and it's the passenger side that gets cold when the center dash slider is in the wrong side.

Wish it was that easy...

 

[LaOutbackTrail]

Pulled the dash apart to see that the mechanisms moving the mixing flap works, and there is a definite sound of the flap moving. Checked the hoses to the heater core. Kinked. straightened them out as best I could.... but still no heat.

Apparently there is an electric switch/motor on the heater core that I need to check, if I can find it. Can anyone confirm its location?

 

[94monster]

I had the whole dash apart to have my heater core repaired due to a leak and i never saw any kind of switch on or near the core.... If your core has a leak it may be one of the little hoses that connects the core to the tubes that go through the fire wall

 

[RU55ELL]

Im not sure if he will reply before he leaves to go to Big Bend, but he did a coolant flush, fixed the kinks and all is working in good order now.

 

[scrubber3]

The coolant flush will help for a bit. A month or two. Then it'll probably get cold again. Mine spits out warm air as long as it isn't too frigid outside. I'm guessing the heater cores are prone to scaling. Hence the reason they make warm air for a bit, then get cold again. I've flushed my heater core out at least 4 times. Same thing every time. Warm for a bit, then back to cold. I just dress warm when I take the Monty out.

 

[off-roader]

Are you using distiller water or tap water when you refill it?

 

[LaOutbackTrail]

I'm also suspecting that the water passages on the engine side of the hoses might have been causing an issue, I recall lots of scaling and build up in those. I hand cleaned all of them... almost to a polish.

The heater core actually flowed nicely from the beginning. Not sure what was up. Not positive there is anything wrong with the heater core....

 

[SD95MontySR]

I had weak heat in my 95 Montero as well. I flushed the old brass/copper heater core with CLR and that worked for a bit. I eventually had to replace the old heater core with a new aluminum unit. My heat works fine now, except for the passenger side vent on the center console, for some reason it always blows cold air.

 

[LaOutbackTrail]

Where'd you get the core?


UPDATE: I Have good heat at 40* or warmer temperatures... Below that and the temps inside the cab are probably only about a few degrees warmer than outside ambient temps....

 

[Justice R]

Messed around with mine today. I took off the hoses going to the core, then used a plastic tube I got from Home Depot to force CLR through it (used good ol' lung power). I used half of a small bottle of CLR going through one direction then the other half going the opposite direction. it seemed quite restricted but did improve as I put more CLR through. Never got an all out flow, but a good improvement. Then I flushed it out with clean water for a while using the garden hose. I also hooked my heater hoses from the engine up on the opposite sides of the core nipples that come through the fire wall, my theory being that if I leave it that way for a while it will reverse flush any gunk out and I'll flush the cooling system for good measure later. It blows nice and warm now, not super hot, but on the upper side of warm, enough to get it nice and toasty inside.

Another thing I noticed after I buttoned it back up and refilled is that if you have any air in the system it will manifest itself up in the core since those hoses go up higher than the rad cap, so park on an incline and or use ramps under the front wheels when filling and squeeze upper rad hose to get bubbles out. Check and top off after thermostat opens. Mine would not heat up until I got most of the air out.

In a nutshell I did 3 things
1. Flush with CLR
2. Hooked up heater hoses in reverse
3. Burped all air out of cooling system that I could