Heater not working

[gimmea250swb]

The heat is moderate at the driver's side and goes to cold on the right. When I switch from vent to defrost you can feel the a short rush of luke warm air and then it goes cold. I checked the actuators behind the glove box and it seems to work freely. I checked the thermostat - the heat comes on the radiator hose quickly after some time.

I suppose the last thing is the heater core?

 

[MikeinNH67]

I just flushed the heater core on my son's S10 today as there was no heat. It wasn't letting any water through. You can tell by feeling the heater hoses near the firewall. If they are not hot when the car is up to temp then the heater core needs to be flushed. Also make sure your coolant is not low.

 

[gimmea250swb]

well, I did a flush on my heater core. Flow is good, no issues there. Any other guesses?

 

[Drcoffee]

If air flow is going to the correct vents, there must be air in the heater core. Either you didnt purge all the air out after flushing coolant. Or you have a coolant leak and the coolant level is too low to reach the heater. Check the radiator and water pump from below for pink crusty leaking. If no leaks, while engine is cold at start up, loosen and gently remove the heater hose from one of the heater core ports on the firewall and let the air out. There should always be coolant flowing as there is no flow valve on the heater circuit.

 

[MikeinNH67]

well, I did a flush on my heater core. Flow is good, no issues there. Any other guesses?

Ok but are the hoses going to and from the heater core hot to touch on the firewall end when the car is up to normal temps? If so then something under the dash is probably the cause, blend door or such. If hot close to the engine but not close to the firewall then there is a flow issue. You could use a laser thermometer to see if there's a huge difference in temp on each end of those hoses.

You mentioned flushing the core, was it plugged at first? Any junk come out?

 

[gimmea250swb]

Ok but are the hoses going to and from the heater core hot to touch on the firewall end when the car is up to normal temps? If so then something under the dash is probably the cause, blend door or such. If hot close to the engine but not close to the firewall then there is a flow issue. You could use a laser thermometer to see if there's a huge difference in temp on each end of those hoses.

You mentioned flushing the core, was it plugged at first? Any junk come out?

Thank you both for your replies. I'll check the temp tomorrow to be more definitive. I'd say the flow was definitely better, but it was by no means plugged. The directional actuator (foot, defrost, vents) works fine. The AC works. I can see the actuator and lever moving when I change the temperature. Is there any chance the actual internal mechanism is broken?

 

[gimmea250swb]

I found this discussion about a broken heater door. My car is dual zone. Maybe I've been checking incorrectly. I'll have to check to see if one zone works and not the other. I assume the driver actuator is on the driver side. I only checked the passenger side.

2005 Toyota 4Runner, Heater Box Repair - YouTube

 

[MikeinNH67]

Thank you both for your replies. I'll check the temp tomorrow to be more definitive. I'd say the flow was definitely better, but it was by no means plugged. The directional actuator (foot, defrost, vents) works fine. The AC works. I can see the actuator and lever moving when I change the temperature. Is there any chance the actual internal mechanism is broken?

Could be but I've never had to go into mine so not sure. I do know the recirc/fresh air function is interesting to watch. I believe you can see that with the cabin filter removed.

Interesting video, doesn't look like fun to pull that dash all apart.

 

[gimmea250swb]

Okay, good news. I confirmed it the heater core now. Had flow when I flushed it, but maybe there is air in there. I touched the aluminum tubes coming off the core by the accelerator pedal. One is hot the other absolutely is not. It was easy for me to check there because I checked the driver's side actuator there which was working fine. So now, I need to burp and/or confirm again I've got decent flow.

If no leaks, while engine is cold at start up, loosen and gently remove the heater hose from one of the heater core ports on the firewall and let the air out. There should always be coolant flowing as there is no flow valve on the heater circuit.

Just to confirm on this, I should remove the exhaust hose on the heater core, correct?

Will there be any flow at all before the thermostat pops? My guess is no, but would like to check.

Also, when the thermostat pops how much fluid will come out? Should I have someone on the key ready to turn the car off or just walk over there and pull it off myself?

Thanks!!

 

[gimmea250swb]

Okay, good news. I confirmed it the heater core now. Had flow when I flushed it, but maybe there is air in there. I touched the aluminum tubes coming off the core by the accelerator pedal. One is hot the other absolutely is not. It was easy for me to check there because I checked the driver's side actuator there which was working fine. So now, I need to burp and/or confirm again I've got decent flow.

If no leaks, while engine is cold at start up, loosen and gently remove the heater hose from one of the heater core ports on the firewall and let the air out. There should always be coolant flowing as there is no flow valve on the heater circuit.

Just to confirm on this, I should remove the exhaust hose on the heater core, correct?

Will there be any flow at all before the thermostat pops? My guess is no, but would like to check.

Also, when the thermostat pops how much fluid will come out? Should I have someone on the key ready to turn the car off or just walk over there and pull it off myself?

Thanks!!

 

[rdruss]

The engine block and heads will be pressurized by the water pump regardless if stat open or not, just recirculates coolant before stat opens, so I would say yes, you will have coolant flow in/out of heater core when engine running. Although I would guess there may be a valve that allows flow into the heater core as you demand heat in the cab.

 

[Drcoffee]

Probably not a good plan while the engine is running. So its hot on one hose but not the other. With the engine cold, disconnect both hoses from the heater core in the engine bay. If you have an air compressor, set it at 5 psi and try blowing air thru it. If air can flow, use a garden hose and try to flush out the core. Normally there is a plastic reducer inside one of the heater hoses to control water flow, so dont force a lot of pressure in the hose.

How to Flush a Heater Core Safely (with a garden hose) - YouTube

 

[MikeinNH67]

I wouldn't worry about air in the lines honestly, it should purge itself but you can park the car on a hill with the nose up to help. Even if the thermostat is closed it lets some coolant through as there is usually a little hole in it on one side.

This is my process for flushing. I think you said you've already done this once so maybe unneeded info.

-move the hose clamps and get the rubber hoses broken free so they spin (this is usually the hardest part)
-pinch off the hoses a few inches from the firewall with needle nose vice-grips but be gentle then pull the hoses off the metal core barbs.
-put some clear hoses on each of the metal heater core hoses you just disconnected from.
-with a hose run water through in both directions until clear, I dump it into a 5 gallon bucket. you'd be amazed at the junk that comes out.
-if it still seems weak you can put some CLR in there and let it sit for a couple mins before flushing out but some folks are afraid of putting their old core through that. I've never seen a leak after.

Doing this way you only loose a cup or 2 of coolant if that. I do like to blow through it with my mouth to see how different the change is. Best with clean hoses of course. :-D

 

[gimmea250swb]

Okay, I’m a bit confused now. I bought better fitting hose (black) and clamped them on. I bought a fish tank pump and got great flow going both ways. Since I was already there I used a flush chemical from Advance Auto. I used hot water for the recirculating flush. I touched both heater core tubes and they were hot. Yay, right? I also checked the black heater hoses and they were hot as expected. I flushed with water, blew it out, filled with coolant and re attached the engine hoses thinking I was good to go. Idled the car to temperature and nothing. No temp at the hoses or tubes. There’s a dripping leak at the hoses but nothing significant.

I did this at night so maybe the small leak is more than I could tell. I’ll adjust the clamps tomorrow.

I’ll also pull the hoses again and check for flow. Not sure why I had a hot tube the other day and not now.

Any thoughts?

 

[gimmea250swb]

Good news, call off the dogs. I adjusted the hose to eliminate leaks and tapped off the radiator. Let it run and I’m good to go! Thanks for all the help.

 

[MikeinNH67]

Good to hear and thanks for the update.

 

[dirkviggler]

Heater issue

So if I'm having a similar issue, what would be the next logical part to check? Engine reaches operating temperature and the Thermostat is opens. Both pipes (under the steering wheel) at the heater core get hot, but there is no warm air blowing. A couple years ago, the A/C blower motor went bad so I replaced it. I do occasionally get a buzzing sound from within the glove box area which from the videos that I've seen on youtube seems to be the air mix servo motor / blend door actuator. Upon inspection, I can see things are moving in there when I switch from heat to cool and back again. But I never get any hot air. Is the correct next step to just go ahead and replace the blend door actuator and its associated parts?

 

[AuSeeker]

So if I'm having a similar issue, what would be the next logical part to check? Engine reaches operating temperature and the Thermostat is opens. Both pipes (under the steering wheel) at the heater core get hot, but there is no warm air blowing. A couple years ago, the A/C blower motor went bad so I replaced it. I do occasionally get a buzzing sound from within the glove box area which from the videos that I've seen on youtube seems to be the air mix servo motor / blend door actuator. Upon inspection, I can see things are moving in there when I switch from heat to cool and back again. But I never get any hot air. Is the correct next step to just go ahead and replace the blend door actuator and its associated parts?

What model T4R do you have...SR5, Limited, Sport Edition?

I ask because the Limited has a dual zone system, driver's side and then passenger's side, all other models have a single zone system, if you have a Limited is there no heat on both the driver's side and the passenger side?

That all being asked, I think your issue is the blend door actuator, only one for a single zone, two for the dual zone but both may not be bad.

 

[dirkviggler]

What model T4R do you have...SR5, Limited, Sport Edition?

I ask because the Limited has a dual zone system, driver's side and then passenger's side, all other models have a single zone system, if you have a Limited is there no heat on both the driver's side and the passenger side?

That all being asked, I think your issue is the blend door actuator, only one for a single zone, two for the dual zone but both may not be bad.

SR5

Thanks for the response!

 

[McLoven1t562]

Probably not a good plan while the engine is running. So its hot on one hose but not the other. With the engine cold, disconnect both hoses from the heater core in the engine bay. If you have an air compressor, set it at 5 psi and try blowing air thru it. If air can flow, use a garden hose and try to flush out the core. Normally there is a plastic reducer inside one of the heater hoses to control water flow, so dont force a lot of pressure in the hose.

How to Flush a Heater Core Safely (with a garden hose) - YouTube

that's what I did and even though I saw almost zero debris come out, I was lucky enough to hook it all back up and sure enough I got my heat back =]