Little heat from front vents (1 Viewer)

[Grumvee]

Hi Mud!

I’m having a problem with the heating system in the front of the vehicle. It began today on our drive up to the Sierras for a ski weekend. <sigh>

Symptom: very little heat coming out of the front vents, regardless of which vents I have it set to. It is blowing a SOME hot air… but not much. And unfortunately barely enough to keep the windshield free of fog.

The rear heating system is working fine.

Coolant level is normal.

Vehicle is a 2011 LX with 135k miles. Water pump and themostat were replaced at 120k, and radiator at 90k.

I think the heater core may have failed. This article (Toyota Land Cruiser: Heater Not Working Diagnosis | Drivetrain Resource - https://www.700r4transmissionhq.com/toyota-land-cruiser-no-heat/) says that heater cores can leak when they fail, and in fact the passenger floor mat is damp. Is there a separate heater core for the front and the rear systems? If so, that would explain why one system is working and the other not.

Thoughts? Suggestions?

Any concerns with using the system in this condition? We're ~150 miles from home. I will keep an eye on the coolant level, obviously, but it doesn’t seem like it is leaking quickly, if it is indeed leaking.

Thx!

 

[Grumvee]

I don't have my shop manuals available where I am. If anyone has a reference for where the heater core(s) are located, that would be helpful. Then I can check whether the hoses are getting hot and perhaps be able to diagnose what's going on. Thx!

 

[bloc]

Heater core is in the center of the dash. The two ~1” hoses that split off the passenger side of the engine and go through the firewall are the relevant ones.

If the floorboard is damp it isn’t coming from the heat core because your coolant would be low. The water must be coming from something else.. sunroof drain or maybe the infamous cowl leak into the recirculate vent.

That could be getting the floor harness wet leading to other electrical issues.

Pull up the door sill trim on the side with the water and see whether any is in the cavity the harness sits in.

 

[Grumvee]

Miraculously, the heater issue seems to have resolved itself. Strange.

Regarding the damp carpet on the passenger side... it is slight, and I'm still investigating. Could be caused by our weekend in the snow. I'll dry it out and assess.

Thx.

 

[mahoolaha]

Miraculously, the heater issue seems to have resolved itself. Strange.

Regarding the damp carpet on the passenger side... it is slight, and I'm still investigating. Could be caused by our weekend in the snow. I'll dry it out and assess.

Thx.

Might want to check to see if cabin air filter is wet if it happens again. Whole other thread on that.

 

[CharlieS]

Might want to check to see if cabin air filter is wet if it happens again. Whole other thread on that.

I like this line of thinking. If you had water intrusion, say from the common cowl leak, that got the cabin air filter wet, then it froze, it would impact heating at the front of the cabin (restrict air flow, maybe even cool any air that makes it past as it blows over the ice), and as the water in the cabin air filter melts from having hot air on it, water drips onto the floor (typically after saturating the sound padding of the dash under tray). It all adds up.

 

[Sandroad]

Hi Mud!

I’m having a problem with the heating system in the front of the vehicle. It began today on our drive up to the Sierras for a ski weekend. <sigh>

Symptom: very little heat coming out of the front vents, regardless of which vents I have it set to. It is blowing a SOME hot air… but not much. And unfortunately barely enough to keep the windshield free of fog.

The rear heating system is working fine.

Coolant level is normal.

Vehicle is a 2011 LX with 135k miles. Water pump and themostat were replaced at 120k, and radiator at 90k.

I think the heater core may have failed. This article (Toyota Land Cruiser: Heater Not Working Diagnosis | Drivetrain Resource - https://www.700r4transmissionhq.com/toyota-land-cruiser-no-heat/) says that heater cores can leak when they fail, and in fact the passenger floor mat is damp. Is there a separate heater core for the front and the rear systems? If so, that would explain why one system is working and the other not.

Thoughts? Suggestions?

Any concerns with using the system in this condition? We're ~150 miles from home. I will keep an eye on the coolant level, obviously, but it doesn’t seem like it is leaking quickly, if it is indeed leaking.

Thx!

There is a Customer Support Program on failed servos that direct airflow. It can be intermittent. I don’t know if 2011 is included, but search for 20TE01.

 

[Grumvee]

@Sandroad - Thx for the lead... but it looks like it only affects MY 2016 and 2017

https://static.nhtsa.gov/odi/tsbs/2021/MC-10187255-9999.pdf

 

[Grumvee]

To recap, the problem resolved on its own. Which is great... but I'm still trying to chase it down to avoid it happening again.

One potential new clue. I ran TechStream and there is a historical code I haven't seen before: B1442 ("Air inlet damper control server motor").

Cleared that code and will see if it reappears.

I searched the forum for that code and nothing helpful came up.

 

[bloc]

Be sure your recirc flap is working correctly.

 

[Katkon]

Be sure your recirc flap is working correctly.

Funny you mention this: mine was literally repaired under warranty. Drove home and the car got incredibly warm (heating was on, and it was chilly outside). I don't remember it ever warming up that quickly which made me wonder whether the broken AC recirculation flap could impact heating. I have no idea - may just have been coincidence....

 

[bloc]

Funny you mention this: mine was literally repaired under warranty. Drove home and the car got incredibly warm (heating was on, and it was chilly outside). I don't remember it ever warming up that quickly which made me wonder whether the broken AC recirculation flap could impact heating. I have no idea - may just have been coincidence....

I think it can. Partly when the computer detects it isn’t working right it may change how it utilizes the hot/cold damper door which is a different part.. but all part of the same logic system.

 

[Grumvee]

@bloc - Good thought, but yes, recirc motorized flap is working