Odd HVAC issue

Hey forum

For the record, I have an 07 crewmax limited. It has dual temperature zones. I noticed a creaking noise from under the dash when I would turn off the truck before, I don’t seem to hear it now. I did the thermostat, coolant, radiator and water pump in the summer. The coolant I took out of the truck was very clean and bright pink. I replaced it with genuine Toyota coolant.

I am having an issue with my drivers side heat on my tundra. This issue seems to have started after I had my truck parked (in a heated garage) for about a month. I have hot heat on the passenger side on all modes/settings, but only luke warm on the drivers side. When I turn the dials onto dual and lower the temp on drivers side to cooler temperature than passenger, it does get colder and the airflow INCREASES. When I put it back to hot, the temperature goes to Luke warm and the airflow DECREASES.

I have searched other forums and they seem to have no heat at all when it comes to situations like this. Airflow is not mentioned, nor is luke warm air.

Has anyone experienced with this? I am thinking maybe the blender motor on drivers side isn’t fully opening or closing, causing cold and hot air to be mixed instead of just hot air


Any input is appreciated. It’s currently -40C and will continue to be this cold for a couple weeks. The joys of living in Canada.


If I figure this out on my own, I will put my solution to help anyone having similar issues in the future. Thanks everyone

 

Update #1 - when I put the air to the floor and defrost setting, the floor temperature on drivers side is ice cold, even with interior temperature maxed.

I am going to flush the heater core tomorrow. The door actuator sounds like it’s working but cannot verify if it’s actually moving the blender door.

 

There is a blend door for each side. It may not be functioning properly

 

Hi @FWD Tundra when I change the temperature on drivers side (on dual setting) it sounds like the blender door is moving and it does change the temperature. It just does not blow hot when at the hottest setting.

is there a way to manual move this door to open/closed position to test?

 

I had a very similar issue with my denali (yes different vehicle, but may still be useful.). I replaced the blower and it fixed it. The blower motor was going bad and wouldn't run properly at max.

 

Hey natorobot. The blower fan does blow at max speed. It changes speed as it should by changing speed/fam dial.

did you only have heat on one side with the bad blower?

 

That's correct. I only had it on the passenger side and it was luke warm at best. The defrost didn't work half the time and when it did, it was half what it should have been.

 

Thanks for the reply. I will look into that. I am currently in the process of flushing the heater core. It has put a lot of gunk. Will update with progress

 

Hello

i flushed the heater core with distilled water. I have heat on drivers side now but it is currently -33C where I live. I will 100% confirm tomorrow and do a write up on what I did that remedied my issue

 

So I believe I found a solution to my problem. The blender door motors appear and sound to be working. I figured this was a heater core issue.

I attached a pump driven by a hand drill to clear pvc lines attached to the heater core lines on the firewall. I used coolant system flush split (Preston coolant flush) and dispersed it into 2 - 4L jugs of distilled water. I then pumped the 2 - 4L jugs into the RETURN side of the heater. After doing this, I had a pale of water with dark specs in it. Here are the specs after pumping all 8L of coolant flush. There is still specs in there, so I went ahead and flushed 10 - 4L jugs of distilled water through the heater core. Once this was done, I filled the heater core back with Toyota coolant and burped the coolant system. It was difficult to burp the coolant system as the weather was -33C and the truck did struggled to get warm enough to open the thermostat. Once it did, a few air bubbles burped.

I now have heat on the drivers side. I don’t know if this is a permanent solution, but I am going to flush this heater core again in the spring with a garden hose, then distilled water, then back to coolant.


Here is what the distilled water looked like even after 8L of distilled water and coolant flush

 

I am thinking that you did the coolant job in the summer and probably did not notice no heat as you did not need it. But now that the winter has come you need the heat and you don't have it. My thought is that you had an air pocket in the heater core and that was causing the low heat issue. Now that you did several flushes and top offs, you cleared the pocket of air and now all is well. There is one simple procedure that I use when I do a major coolant drain for the Tstat and Wpump. When I get to the refill I make sure that the heat controls are set to hot and then I will refill the Radiator then take the end of the upper Rad hose off and fill the back of the engine with coolant until you can see it in the hose then connect it, and then check the radiator to make sure it is full. This will save you a burp as the water will fill up all the nooks and crannies that are on the top and behind the engine and as you are filling the air will come out of the Radiator hose as you fill it up. Doing it this way has always worked for me and I have never had to burp a water system. It will relieve your headaches. If you do it different and it works for you, you can disregard this.

Glad to hear that all is well now!

 

Hey there

That may be true @FWD Tundra however I burped the coolant system, with the heat on max twice in the summer time. I don’t remember it being cold then, only found it to be cold in the winter after I stopped driving the truck for a few weeks.

Thanks for the input. I hope this thread helps someone in the future with the same issue.

 

@Krys_tundra Hey bud.. I am having the same darn condition..no heat on drivers side but good heat on passenger side and overall lower volume of air when Temp knob is on heat (full right) vs when it is on cold (full left). But when comparing volume of air when the temp selector is on cold it blows more volume of air than when on heat side. I also was not having any delay on my HVAC controls when I start my truck up. no 30 sec delay or anything.

So to summarize the conditions (for manual air controls)
HVAC knobs set at - blower on full - left temp on full heat (full right) - direction on Face (full left) - Passenger on Sync (full left)

1. HVAC controls work on startup of Truck without any delay. i.e. HVAC system knobs are immediately functional at start up.
2. Heat flow only coming from Passenger side vents. i.e. hot air coming from passenger vents
3. NO heat flow coming from Drivers side. I only get Cold air flow from drivers vents.
4. There is a noticeable improvement in air volume if you move the left temperature knob from heat to cold. The air volume through the vents is higher when in cold vs the hot when you move the temperature knob (the left temp knob) from full cold to full hot.
5. AC works great with more air volume.



I thought it was my servo's on the drivers that were having issue. Now I have opened up my inner dash so will open it up clean up all the servo gears and make sure everything is working. I know its a PITA but Its live and learn.

I shall update everyone on this when I put everything back and see if that makes it works. If not heater flush is next steps. and see if the heater core flush was the real issue.

 

Hey @baraynavab

your issue sounds somewhat different than mine. I did NOT have any air flow difference. Only a temperature difference.
My hvac control looks different than yours, I don’t know if that means the internals are different or not. I have the digital controls.

To me, if you have low air flow on cold but not hot it sounds like a servo issue. I could be wrong.


keep us updated on your progress. I hope this thread helps people avoid paying massive dealership fees.

 

@Krys_tundra So what did you mean here then? highlighted in red bold...
Thanks.

 

I don’t exactly remember. I apologize. Both sides have equal air flow now, however I don’t remember if this changed from flushing the radiator or changing the air cabin filter. Both were done at the same time. I don’t see how flushing the radiator could have fixed air flow.

for what it’s worth, I live in Canada. During this time, we had a cold spell of -30C to -40C and the blower motor seemed to run weak until it warmed up. This may have been a factor.

 

How dirty was your cabin air filter? I had one with a bunch of leaves in it and that decreased the air flow.

 

The cabin airfilter was dirty.. as in it probably was not replaced in a long time. But I changed it out. Only find that the heat makes the volume of air lower.. the AC air volume is a lot more.. to which I think my heater core may have shit around it to block airflow.

 

@FWD Tundra

It wasn’t ridiculously dirty. There were some pieces of dried leaves and other debris but definitely not the worst one I have seen.