No heat

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LoneRanger

LoneRanger

Joined
Mar 15, 2005
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www.barryhause.com
1989 4runner has no heat. search didnt really produce results for me.

I replaced the tstat with a toyota part from the dealer. still no heat. winters coming. I will replace the heater core if need be.
Any suggestions here? What could some other causes be?
The hoses going into the fire wall are hot. The valve appears to be opening when I pull the lever.

stumped in Pearl, MS
 
When you say "no heat", do you really mean no heat at all? Or just not very warm?

Are you sure the valve is opening? Are both hoses hot?

Is there air coming out the vents/outlets when the blower is on High? You might want to pull the fan out, reach inside and feel for a mouse nest or other blockage.

Do you have AC? Still hooked up?
 
KLF said:
When you say "no heat", do you really mean no heat at all? Or just not very warm?

Are you sure the valve is opening? Are both hoses hot?

Is there air coming out the vents/outlets when the blower is on High? You might want to pull the fan out, reach inside and feel for a mouse nest or other blockage.

Do you have AC? Still hooked up?
Click to expand...

in reverse: AC blows cold. I replaced the compressor in August.
Blower and vents are fine. Switch works in all 3 positions.
Both hoses are hot.
the air, if anything could be described as barely noticably warmer. Or not at all.

What does the Dr. say?
 
Hmmm... well I'm trying to think of anything else it could be before you start the awful job of pulling the heater core.

Having AC means you can't easily pull the section of ductwork behind the glove box, and look directly at the heater core for blockage.

I have read about folks "cleaning" a heater core out with Muriatic acid. I tried it once with an old radiator and I think it helped, but only for awhile. Might be worth a try, but it's a messy job.
 
KLF said:
Hmmm... well I'm trying to think of anything else it could be before you start the awful job of pulling the heater core.

Having AC means you can't easily pull the section of ductwork behind the glove box, and look directly at the heater core for blockage.

I have read about folks "cleaning" a heater core out with Muriatic acid. I tried it once with an old radiator and I think it helped, but only for awhile. Might be worth a try, but it's a messy job.
Click to expand...

thanks.
i read about the muriatic acid. I may try that before I try to replace the core.
 
Something I just remembered when I R&R'd the heater box for my truck. There is a damper in this box that directs how much air gets sent through the heater coil, and how much bypasses it. It's on the upstream side of the HVAC system. The lever on the dash that controls temp actually does 2 things: it controls the valve on the firewall, but it also has another cable to controls this damper. If this 2nd cable has somehow gotten detached, maybe the damper is stuck in the position to send all the air past the core instead of through it.

Does this make sense?

The cable is attached to a lever on the bottom of the heater box, middle of the dash, right behind the heater outlet for the passenger feet. Check that out, move the lever back and forth, try to hear the damper flopping back and forth inside the heater box.
 
Last edited:
KLF said:
Something I just remembered when I R&R'd the heater box for my truck. There is a damper in this box that directs how much air gets sent through the heater coil, and how much bypasses it. It's on the upstream side of the HVAC system. The lever on the dash that controls temp actually does 2 things: it controls the valve on the firewall, but it also has another cable to controls this damper. If this 2nd cable has somehow gotten detached, maybe the damper is stuck in the position to send all the air past the core instead of through it.

Does this make sense?

The cable is attached to a lever on the bottom of the heater box, middle of the dash, right behind the heater outlet for the passenger feet. Check that out, move the lever back and forth, try to hear the damper flopping back and forth inside the heater box.
Click to expand...

I think that makes sense. I will take a look at it.
 
Not my Toyota, but on a car I have the heat stopped. I isolated the hose circuit for the heater core and hooked up an air compressor pushing through it in reverse. All kinds of crap came out and I have heat again. Apparently, someone had mixed green coolant with G12.
 
KLF said:
Something I just remembered when I R&R'd the heater box for my truck. There is a damper in this box that directs how much air gets sent through the heater coil, and how much bypasses it. It's on the upstream side of the HVAC system. The lever on the dash that controls temp actually does 2 things: it controls the valve on the firewall, but it also has another cable to controls this damper. If this 2nd cable has somehow gotten detached, maybe the damper is stuck in the position to send all the air past the core instead of through it.

Does this make sense?

The cable is attached to a lever on the bottom of the heater box, middle of the dash, right behind the heater outlet for the passenger feet. Check that out, move the lever back and forth, try to hear the damper flopping back and forth inside the heater box.
Click to expand...

That was it! :clap::bounce2:
the flapdoodle inside the ductwork was not attached to the cable. I flipped it by hand and out pours all the hot air I need.
thanks. I love ih8mud.
 
Whats missing?

I took off the glove box door and shined a flashlight up behind the heater controls and disovered the problem. Cable, which opens the damper is not being held in place by the little mount which hangs down from the dash. It looks as if there was a clip of some sort there that is either broken or lost.

Any suggestions for holding this in place? When I hold it by hand and move the lever, it works just fine.
 
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