Heat Isn't Working

Hello everyone. I have been all over multiple forums and cannot seem to find a solution. I have a 99 4Runner SR5. My a/c works perfect. The servo motor works and switches air where it needs to go. Issue is on heat its still cold. The wire that controls opening the heater valve under the hood is shot and doesn't work. However I can manually open the valve. Before the bottom hose was cold. After opening the valve the bottom hose was hot like it was circulating. However still no heat inside. Not sure exactly the issue. No coolant leaks inside or out. Any help would be appreciated.

 

Often, the heater core clogs up with dust, etc, on it's external fins. Clogged core, no air flow through it, it just flows around it. No heat.

Another possibility, as well, is that the downtubes inside the core are clogged with corrosion. Thus, the water can't flow through the core. No heat.

Feel the hose that comes out of the control valve, and goes into (known as gozinta, in electronics parlance) the fire wall. When you have the valve turned to heat, and are you sure that's what it's set to, does the hose get hot? Try both ways, justin case. You never know...
Anywho, if the hose going into the firewall is hot, is the return hose, the one that comes back out of the firewall, hot? If it's not, the heater core is clogged internally. You'll have to replace the core.

If the return hose IS nice and hot, chances are the heater core is clogged with dust, dirt, leaves, whatever, externally. Take the casing off of it, and blow air through it in the reverse direction than the blower does. Beware, you'll get a facefull of whatever is clogging it. I always wear a good dust/mist mask, and safety glasses. You'll be glad you did!
If it's been clogged for a while, it sometimes turns into a cement-like block in the heater cores fins. If it has, either a new heater core is in order, or you'll need to pull it out, and soak it in soapy water to get it to soften and break up.

Hope this is some help...
Pat☺

 

Ok so went hunting under to dash to try and clean everything. All of my controls are manual so I started moving everything to see what it did. This was the only cable that didn't move. With the vehicle on and ac blowing cold I manually pushed the cable in the photo and the heat came on working perfect. Pulled it back and the ac worked again. Easy to access for now but what does it hook up to before I start pulling the dash apart. Also the water valve in the engine bay is stuck open. Ac still works amazing though so not too concerned, it doesn't leak.

 

Nice! Don’t forget to unhook battery to disable the air-bag. When you tear into it.

 

I suspect the cable is for the direction of the air flow. Does it flow onto the windshield, your face, feet and face, etc etc. I would say trace the cable back to it's control on the control panel. You can move the bell crank, and see which control knob moves. It may also be the cable that controls whether the air blows through the heater core, or the AC core. If it's the latter, I think it goes on the dial that controls where the air is directed. It may not move until the knob is in the "fresh air" settings area, as opposed to the recirc section of the knobs throw. Again, move the cable, and see what control knob moves. It could also be the recirc/fresh air slider.

I would also replace the cable to the water control. Do you want to be manually adjusting the water valve all winter? BTW: Are you sure the cable actually broke, or did it just come off the control knob? It goes on the knob that has the red, white, and blue markings. Easy enough to check. Move the end that goes on the water control valve, and see if the end that goes on the knob moves.

Be careful, also, of the water control valve. Mine disintegrated in my mechanic's hands when he went to remove it to work on something else. Being plastic, and having hot water flowing through it, the plastic gets brittle. Since he broke it, he replaced it free for me. I suspect he didn't align the cable correctly, though. I need to check that. I have hot air all the time, and shouldn't. Not hard to align correctly, though.

Did you pull open the heater core casing, and see if it needs cleaning?

And last, yes be VERY careful about the air bags. Remember, they have a 90 second backup power supply. Don't touch anything about them until the 90 seconds, at LEAST, has expired.

I wish you all the best!
Pat☺

 

I need to pull the center console out anyway to do the shifter bushings so I will just pull everything. Have seen a lot with the all manual controls. I have tried finding dash removal videos to see where the cables were going before removing mine with no luck.

When I move the cable manually that controls the heat nothing on the control panel moves. The knob to direct the air to feet, face, etc works perfectly whether the ac is on or I have manually moved the cable to heat. Probably is the one that controls the air going through the heater core or AC because there is an audible sound change in the air blowing when going back and forth to heat and AC.

Have not checked the fresh air vs inside air slider because it did not seem to do anything and I didn't think that would affect whether it is heat or AC. Will look into that too maybe it is disconnected.

When I disconnected the cable to the water valve and moved it with the dial inside the sheath around the firewall moves but not the cable. The cable is also rubbed through where it holds to the water valve like it has been misaligned a long time. Definitely going to be replacing the valve they just think very highly of them lol. cables only $14.

 

Aight. Finally got around to pulling everything out.

Side note: the 4 shifter bushings are a MUST. My shifter moved like a manual would. In drive you could push it forward and it would show neutral while in drive. Did the bushings all play was gone.

So the cable in the picture is attached to the bottom side of the AC controls and is moved by the blue/red temperature dial. I assume this is the blend door that is electronic in some models. My control brackets holding the cables are bent and broken for the blend door and to the water control valve under the hood. Checked parts and pricing. Including the major PITA of pulling everything I am leaving it. I just leave the valve open under the hood. If I want heat I reach around under the passenger side and push the cable. For the A/C I pull it back. A/C works perfect as well as heat.

Thanks everyone.

 

This thread isn't too old so I thought I'd share my experience via video. I just fixed mine yesterday. Works great now. After reading through this and not finding any vids on how to fix it, I recorded my work. Hope this helps! https://youtu.be/VCylds8_1d4