I've seen the problem posted online, but haven't seen anybody post an answer. There will be a slight amount of warm air on passenger side with the fan on high, otherwise nothing on the other settings. Problem only on passenger side, I have checked the coolant level, and it is a 2007. Looking to see how I can troubleshoot before, having to take it in. Blower motor? Thanks
Heater only blowing warm air on drivers side
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Have you recently changed out your radio or took off your dash for any reason?
I ask, because I'm in a similar situation. Only cold air blows out of the passenger side in my car.
When I changed out my radio a while back, I might have blocked or broken a blend door while putting my dash back together. Living in Chicago, it's too cold to take my dash apart again to try and diagnose the problem. Will have to wait a few more months.
I ask, because I'm in a similar situation. Only cold air blows out of the passenger side in my car.
When I changed out my radio a while back, I might have blocked or broken a blend door while putting my dash back together. Living in Chicago, it's too cold to take my dash apart again to try and diagnose the problem. Will have to wait a few more months.
Billynath1988
Senior Member
Same issue, pretty sure its the blend door actuator. its a fairly common issue. I havent fixed it yet but looking at the part price i think its about 50 bucks. I also have no idea how hard it is to get to.. By the time i get around to it, it will probably be spring and ill forget until next winter.
Powder_Hound
New member
I’m working out this exact issue now and completely baffled.
Confirmed Thermostat is good
Coolent level is good
Flushed Heater Core
Hot drivers left face and cooler moving to passenger
Cool air to rear vents
Cool air to passenger lower
Dealership is quoting $1650 to replace heater core due to being “clogged”. But, why would there be some “heat” if heater core is clogged?
I did add a new radio last summer, but I haven’t dug into it to check on alignment of vents. Has anyone ever figured out if it’s a blend door actuator or a savor or WTF else could it be?
Confirmed Thermostat is good
Coolent level is good
Flushed Heater Core
Hot drivers left face and cooler moving to passenger
Cool air to rear vents
Cool air to passenger lower
Dealership is quoting $1650 to replace heater core due to being “clogged”. But, why would there be some “heat” if heater core is clogged?
I did add a new radio last summer, but I haven’t dug into it to check on alignment of vents. Has anyone ever figured out if it’s a blend door actuator or a savor or WTF else could it be?
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jminz
New member
Had same issue recently. Did all the research and was convinced it was heater core or blend actuator. Turns out my radiator was low on coolant even though my reservoir was filled correctly. Topped it off and it blows hot heat on passenger side.
Sent from my SM-G935V using Tapatalk
Sent from my SM-G935V using Tapatalk
hi, with respect to people's concern about interior cab heat (blowing warm on one side cool on the other) I too need help with this too
T4R not getting same temp from passenger side and driver side on "heat" settings. A/C settings seem to be equal.
(my T4R is a 04 V-8 limited with auto-temp control) I am in Canada, it gets cold here so the heat needs to work.
-If I select "hi" temp (max hot setting on both drive and passenger side) and use the climate control manually, I select heat location and the fan speed, then I get good solid warm air everywhere.
-If I select select "hi" temp (max hot setting) and then select the "auto" setting, then I get good solid warm air everywhere.
-* If I select select a value such as "26" temp and then select the "auto" setting, this is where the problem happens. example the driver side will blow at 26 deg C (79F), but the passenger side only blows at 19 deg C (66F) or cooler.
-at this point if I adjust the passenger side tempt to about 31, then both sides will be similar
-in the summer I do hear some random "gurgling" noise (or it maybe like a stripped plastic gear noise) that seems to come from behind the radio or behind the glove box
I feel like this should be more of a blend door or temp sync/calibration issue?
has anyone actually fixed this issue?
(my coolant is relatively new, it is full, it has been "burped", a/c works fine)
T4R not getting same temp from passenger side and driver side on "heat" settings. A/C settings seem to be equal.
(my T4R is a 04 V-8 limited with auto-temp control) I am in Canada, it gets cold here so the heat needs to work.
-If I select "hi" temp (max hot setting on both drive and passenger side) and use the climate control manually, I select heat location and the fan speed, then I get good solid warm air everywhere.
-If I select select "hi" temp (max hot setting) and then select the "auto" setting, then I get good solid warm air everywhere.
-* If I select select a value such as "26" temp and then select the "auto" setting, this is where the problem happens. example the driver side will blow at 26 deg C (79F), but the passenger side only blows at 19 deg C (66F) or cooler.
-at this point if I adjust the passenger side tempt to about 31, then both sides will be similar
-in the summer I do hear some random "gurgling" noise (or it maybe like a stripped plastic gear noise) that seems to come from behind the radio or behind the glove box
I feel like this should be more of a blend door or temp sync/calibration issue?
has anyone actually fixed this issue?
(my coolant is relatively new, it is full, it has been "burped", a/c works fine)
I was having heating issues recently and I cleaned the sensor hole by your right knee and my heater started functioning as intended. A little bit of dust had clogged up the sensor and was making the heater not function properly. FWIW, I have the blend door noises as well, but it's working again. Good luck!
Sensor hole? On passenger side? Any further guidance on this would be appreciated. Maine. Winter. Help!
AuSeeker
Elite Member
Directly below the ignition switch are some little slots, mounted behind the slots on the trim panel is the cabin air temperature sensor, dust can clog the slots or the coat the surface of the sensor causing false temperature readings in the cabin, clean the slots and the sensor with a little compressed air or wiping it clean if you find it dirty or dusty.
Also sometimes the connector to the sensor can be a little loose, make sure it's clipped on properly.
AuSeeker
Elite Member
Probably not if it's only on one side of the vehicle, but if you're getting warm air on the driver's side but cold air on the passenger's side it sounds like you have a Limited model with "Dual Air" system, if so the passenger's air mix/blend door actuator/servo most likely needs replacing, because it's stuck and or not working and not moving the blend door to allow air from the heater core to enter that side.
There's HVAC actuators behind and to the left of the glove box, it's a pain to get to them and replace the bad one/s, if you listen closely you may hear either a clicking or buzzing sound of the bad actuator trying to work.
BlackWorksInc
New member
Likely your heater core is plugged up.
I just responded to a fellow member who cleaned theirs out and asked for an explanation as to why it blows hot on the driver's side but not the passenger's side.
The heater core on 4Runners looks something like this:
The inlet and outlet lines are routed on the driver's side of the HVAC box and are on the same side tank.
The reason for this is because the heater core is dual pass design which looks something like so:
What likely happens is that the flow of the coolant through the heater core is either partially or completely restricted preventing a proper fluid circuit. Now why does this translate into only the driver's side vents blowing hot and the passenger's side blowing cold? Mainly because the heater core is not a critical component of the cooling system and is piped in as a parallel circuit, so when it's clogged/restricted the heated coolant just sits at the inlet side (even though there might not be flow through the heater core the coolant itself will heat up because it's trying to reach a stable thermal equilibrium) and heats up that side tank. With little to no flowing coolant through the heater core, the other half of it just stays cool. The way the heater core is installed in the HVAC box, the inlet/outlet side of the heater core is located on the driver's half of the system (despite it being a normal HVAC system, the way the air flows through the chamber it basically acts as "driver's half and passenger's half" in the case of a dual climate system they have a individual blend air doors for the left and right half front vent outlets so you can take advantage of that quirk) so the air being pushed through the left side of the heater core heats up and the air flowing through the right half of the heater core stays relatively cool.
This is also why when the evaporator core of the air conditioning system is low on refrigerant, clogged, and/or restricted it blows cold on the passenger's side and warm on the driver's side. The evaporator core is mounted on the passenger's side of the HVAC assembly and it's inlet/outlet are on the right side of the evaporator core.
Post Note-
I will also recommend the same thing I said to the member that messaged me. You can try an flush the heater core and get it working again (which is what they did and were able to get it cleaned out) or replace it, but after you do that make sure you drain as much of the water out of the system as possible and use either Toyota SLLC (Super Long Life Coolant aka "Toyota Pink) or something similar to it (I want to say Valvoline has an Asian formula that's fairly similar?) You really want to make sure you use the correct coolant, Toyota's SLLC is a non-silicate, non-amine, non-nitrite and non-borate coolant with OAT (organic acid technology); so if you're going to substitute the Toyota stuff, make sure the coolant your using matches those requirements. I would then consider flushing your system again around your next oil change or the one after that (about 5-10k) as a conservative measure to get that crap out. After you've done all that change your coolant with the pink stuff (or equivalent) every 5yr/50k (Toyota's recommendation for SLLC systems is the first service is due 10yr/100k after that they recommend 5yr/50k intervals).
I just responded to a fellow member who cleaned theirs out and asked for an explanation as to why it blows hot on the driver's side but not the passenger's side.
The heater core on 4Runners looks something like this:
The inlet and outlet lines are routed on the driver's side of the HVAC box and are on the same side tank.
The reason for this is because the heater core is dual pass design which looks something like so:
What likely happens is that the flow of the coolant through the heater core is either partially or completely restricted preventing a proper fluid circuit. Now why does this translate into only the driver's side vents blowing hot and the passenger's side blowing cold? Mainly because the heater core is not a critical component of the cooling system and is piped in as a parallel circuit, so when it's clogged/restricted the heated coolant just sits at the inlet side (even though there might not be flow through the heater core the coolant itself will heat up because it's trying to reach a stable thermal equilibrium) and heats up that side tank. With little to no flowing coolant through the heater core, the other half of it just stays cool. The way the heater core is installed in the HVAC box, the inlet/outlet side of the heater core is located on the driver's half of the system (despite it being a normal HVAC system, the way the air flows through the chamber it basically acts as "driver's half and passenger's half" in the case of a dual climate system they have a individual blend air doors for the left and right half front vent outlets so you can take advantage of that quirk) so the air being pushed through the left side of the heater core heats up and the air flowing through the right half of the heater core stays relatively cool.
This is also why when the evaporator core of the air conditioning system is low on refrigerant, clogged, and/or restricted it blows cold on the passenger's side and warm on the driver's side. The evaporator core is mounted on the passenger's side of the HVAC assembly and it's inlet/outlet are on the right side of the evaporator core.
Post Note-
I will also recommend the same thing I said to the member that messaged me. You can try an flush the heater core and get it working again (which is what they did and were able to get it cleaned out) or replace it, but after you do that make sure you drain as much of the water out of the system as possible and use either Toyota SLLC (Super Long Life Coolant aka "Toyota Pink) or something similar to it (I want to say Valvoline has an Asian formula that's fairly similar?) You really want to make sure you use the correct coolant, Toyota's SLLC is a non-silicate, non-amine, non-nitrite and non-borate coolant with OAT (organic acid technology); so if you're going to substitute the Toyota stuff, make sure the coolant your using matches those requirements. I would then consider flushing your system again around your next oil change or the one after that (about 5-10k) as a conservative measure to get that crap out. After you've done all that change your coolant with the pink stuff (or equivalent) every 5yr/50k (Toyota's recommendation for SLLC systems is the first service is due 10yr/100k after that they recommend 5yr/50k intervals).
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That member was me 
Still having issues, but i think i might be dealing now with a blend door problem. I have posted this on another T4R forum too, so some of you might see it twice!
Getting ready for winter. Oil/filter change 2 days ago, yesterday back-flushed heater core. Was partly blocked (was minimal, if any, heat from the passenger side centre dash, windshield or floor vents and nothing by the time you reached the window) and I have lots of heat out of the passenger side vents again
... except for the window vents 
. They still blow ambient temperature. So I think I have/had 2 problems. One was the heater core. Second is perhaps a blend door stuck/broken? If my memory serves me, I think I read that the SR5 has 2 blend doors on a single "rod" operated by a single actuator? I don't have dual climate control, so should be just one actuator, yes? But 2 separate doors (?), and perhaps the one on the passenger side is stuck/broken, and not opening when I ask for an increase in temperature?
Everything on the driver's side works great. Passenger side I now have good heat from the centre dash (though doesn't seem quite as hot as the drivers side - will pull the meat thermometer out of the cupboard today and recheck), floor and windshield defrost. But no heat at the passenger window vents - either climate or defrost vents. And the windshield defrost is only hot near the centre of the windshield. Farther you go toward the side, the cooler the air gets.
Air flow is fine. Lots of air moving, but no heat. Whatever the ambient temperature is, that's what's coming out. NO heat at all. Not even warm. Could it be that I still have a partially clogged heater core? And that the passenger side of it isn't getting enough coolant circulating? Better than it was, but still clogged enough that I'm not getting anything toward the right?
Everything I can track down talks about a bad actuator, but that is if they have either no heat, or no a/c on both sides, or dual climate control and only one side affected. I don't hear anything clicking, and since everything works perfectly on the driver's side, I assume the servo is working properly. Today I will be crawling around on the passenger floor to check that actuator.
Any comments, information or suggestions would be greatly appreciated. BTW, I am mechanically inclined, and have the skinned knuckles to show for it, but not a mechanic, and in no position to start pulling apart the centre of the cabin!
Still having issues, but i think i might be dealing now with a blend door problem. I have posted this on another T4R forum too, so some of you might see it twice!
Getting ready for winter. Oil/filter change 2 days ago, yesterday back-flushed heater core. Was partly blocked (was minimal, if any, heat from the passenger side centre dash, windshield or floor vents and nothing by the time you reached the window) and I have lots of heat out of the passenger side vents again
... except for the window vents . They still blow ambient temperature. So I think I have/had 2 problems. One was the heater core. Second is perhaps a blend door stuck/broken? If my memory serves me, I think I read that the SR5 has 2 blend doors on a single "rod" operated by a single actuator? I don't have dual climate control, so should be just one actuator, yes? But 2 separate doors (?), and perhaps the one on the passenger side is stuck/broken, and not opening when I ask for an increase in temperature?Everything on the driver's side works great. Passenger side I now have good heat from the centre dash (though doesn't seem quite as hot as the drivers side - will pull the meat thermometer out of the cupboard today and recheck), floor and windshield defrost. But no heat at the passenger window vents - either climate or defrost vents. And the windshield defrost is only hot near the centre of the windshield. Farther you go toward the side, the cooler the air gets.
Air flow is fine. Lots of air moving, but no heat. Whatever the ambient temperature is, that's what's coming out. NO heat at all. Not even warm. Could it be that I still have a partially clogged heater core? And that the passenger side of it isn't getting enough coolant circulating? Better than it was, but still clogged enough that I'm not getting anything toward the right?
Everything I can track down talks about a bad actuator, but that is if they have either no heat, or no a/c on both sides, or dual climate control and only one side affected. I don't hear anything clicking, and since everything works perfectly on the driver's side, I assume the servo is working properly. Today I will be crawling around on the passenger floor to check that actuator.
Any comments, information or suggestions would be greatly appreciated. BTW, I am mechanically inclined, and have the skinned knuckles to show for it, but not a mechanic, and in no position to start pulling apart the centre of the cabin!
Just went out for a nice long drive. Could only get the coolant temp up to 186F as it is pretty cool out today. Full heat with fan on. (I got REALLY warm in there!!) Used the meat thermometer... Driver's side centre dash vent at 145F, passenger side 120F. Driver's window vent 130F, passenger window vent 80F.
Checked the heater hoses - incoming ~180F outgoing ~165F (which from what I read is about right with the heater on and the fan running). Just went out and checked with fan off, on hi heat. Engine had cooled down to 175F. I let it run for a few minutes to get everything circulating and both inlet and outlet hoses are 164F. Which is also what I believe I should expect with a good heater core. Or would I also see that with a partly blocked core, given the design of our heater cores?
I did find a wee bit of foam which blew into the driver side window vent, which likely worked it's way loose from one of the vents (thermometer probe pulled it loose?)
Haven't crawled around on the passenger floor to pull the glove box out and check the actuator yet. My back is bugging me from the contortions of trying to manipulate the heater hoses and clamps yesterday. Had to use a step stool to reach in there comfortably. Don't need to tweak it. I'll give it a couple of days to settle down before I abuse it again.
So, opinions? Heater core? or blend door? Still leaning toward heater core. Maybe wants another good flush or two. Can't afford to do a replacement - just did a head gasket last fall, and a trip across the country with the trailer so the big repair budget is blown for the year.
Checked the heater hoses - incoming ~180F outgoing ~165F (which from what I read is about right with the heater on and the fan running). Just went out and checked with fan off, on hi heat. Engine had cooled down to 175F. I let it run for a few minutes to get everything circulating and both inlet and outlet hoses are 164F. Which is also what I believe I should expect with a good heater core. Or would I also see that with a partly blocked core, given the design of our heater cores?
I did find a wee bit of foam which blew into the driver side window vent, which likely worked it's way loose from one of the vents (thermometer probe pulled it loose?)
Haven't crawled around on the passenger floor to pull the glove box out and check the actuator yet. My back is bugging me from the contortions of trying to manipulate the heater hoses and clamps yesterday. Had to use a step stool to reach in there comfortably. Don't need to tweak it. I'll give it a couple of days to settle down before I abuse it again.
So, opinions? Heater core? or blend door? Still leaning toward heater core. Maybe wants another good flush or two. Can't afford to do a replacement - just did a head gasket last fall, and a trip across the country with the trailer so the big repair budget is blown for the year.
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I just replaced the drivers side Air Mix Damper Servo in my Limited. In the Limited there are Left and Ride side Air Mix Damper Servos. The left side servo is easy to remove. The blend door can be worked manually which should direct heat to the drivers side. The right side servo is partially blocked by the blower motor housing. I think it is possible to see and feel the servo working with the HVAC control.
Did replacing the drivers side Air Mix Damper Servo on your limited fix this issue? Having this issue right now, what I’ve done so far:
- Flushed heater core twice both ways
- drained and filled coolant with pink stuff
I’m having the exact same issue where my drivers side blows perfect heat, scorching hot, passengers side is blowing ambient, no heat at all.
- Flushed heater core twice both ways
- drained and filled coolant with pink stuff
I’m having the exact same issue where my drivers side blows perfect heat, scorching hot, passengers side is blowing ambient, no heat at all.
