HVAC Issues - Diagnosis help - Toyota Tundra Forums : Tundra Solutions Forum
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post #1 of 5 (permalink) Old 03-26-2019, 05:37 PM Thread Starter
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HVAC Issues - Diagnosis help

I purchased a used 2013 Sequoia Limited. It had a full service history and one of the last times it went to service, I saw "customer says poor heat". Sure enough, couple of days into ownership, the heat is barely there. Here is what I do know...

1. Coolant is full(unless there is a big air pocket that's being stubborn). Removing the radiator cap it looks like the coolant is moving so that should eliminate the water pump/thermostat. Tho, it could be partially working

2. The mode selection works.. so when it's floor, it blows floor.. when it's front.. blows front.. defrost.. blows up at the defrost.

3. One thing I noticed, with everything synced(drivers/passenger and rear), the front is blowing luke warm but the rear is blowing ice cold even when the temp setting is set to "HI"

4. When I feel the heater core hoses.. 1 is hot for sure.. the other is not nearly as hot???

Where should I start? One friend said to flush the heater core?? Another said the dampers are not functioning right? What is the best procedure to diagnose the issue? Also, can the control head unit be sending the wrong info even if its displaying the correct temp i'm asking?

Thank you for any help!!

2013 Sequoia Limited Pyrite Mica w/210k miles and climbing
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post #2 of 5 (permalink) Old 03-28-2019, 09:36 AM
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Re: HVAC Issues - Diagnosis help

The first generation Seq. used a valve to allow coolant to the heater core, but I don't think the 2nd gen has one. The trouble with any used car is finding out what has work has been done on it. I haven't had to work on the cooling system on my 2017 but I had a similar problem on my 2002 after changing the coolant. It was air in the system that eventually worked its way out. Raising the front of the vehicle helped get the air out of the rear HVAC.





As far as I can tell from the shop manual, there isn't a special procedure for adding coolant to the gen 2 Seq. Basically fill it up and squeeze the radiator hoses to work the air out. My guess is that someone has opened up the system and there is air in it, since you don't have heat in the rear and only partial in the front. It is was a problem with the dampers, I think it wouldn't affect both the front and rear... unless there is something going on with the HVAC computer control system.



Good luck! Let us know what you find out.
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post #3 of 5 (permalink) Old 03-28-2019, 11:45 AM
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Re: HVAC Issues - Diagnosis help

Your second friend might be right but you better hope not. If you bought it from a dealer and you have some warranty you better push hard to get it fixed on their dime. Read the thread below and you will see why you want this fixed on their dime not yours.


https://www.tundrasolutions.com/foru...de-07-crewmax/
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post #4 of 5 (permalink) Old 03-31-2019, 06:59 AM Thread Starter
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Re: HVAC Issues - Diagnosis help

Quote:
Originally Posted by twoheeldrive View Post
The first generation Seq. used a valve to allow coolant to the heater core, but I don't think the 2nd gen has one. The trouble with any used car is finding out what has work has been done on it. I haven't had to work on the cooling system on my 2017 but I had a similar problem on my 2002 after changing the coolant. It was air in the system that eventually worked its way out. Raising the front of the vehicle helped get the air out of the rear HVAC.





As far as I can tell from the shop manual, there isn't a special procedure for adding coolant to the gen 2 Seq. Basically fill it up and squeeze the radiator hoses to work the air out. My guess is that someone has opened up the system and there is air in it, since you don't have heat in the rear and only partial in the front. It is was a problem with the dampers, I think it wouldn't affect both the front and rear... unless there is something going on with the HVAC computer control system.



Good luck! Let us know what you find out.
It was serviced at a local Toyota dealer.. right before being sold to CarMax, they went in for poor heat.. they tech replaced the radiator(states it was clogged) and thermostat. My feeling is, he never properly flushed the system and gunk is clogging up the heater cores. I'm hoping a simple heater core flush will solve my problem.

I agree on your damper thought process.. i would think only one of the 3 zones would not be working properly. Plus, when the vehicle is hot, and i feel the in/out heater core hoses, only one of the hoses is really hot.. the other is not very hot at all.

Will definitely post up results once I figure it out. I'm hoping this week i'll have time to flush the heater cores.

Quote:
Originally Posted by cheapskate View Post
Your second friend might be right but you better hope not. If you bought it from a dealer and you have some warranty you better push hard to get it fixed on their dime. Read the thread below and you will see why you want this fixed on their dime not yours.


https://www.tundrasolutions.com/foru...de-07-crewmax/
Nah, I bought it knowing the issue.. this is a 2013 with 210,000 miles on it.. no warranty for sure
I've seen that thread.. worst case scenario if the heater core needs replacing, I guess i'll be taking a dash apart. Still worth it for the deal I got

2013 Sequoia Limited Pyrite Mica w/210k miles and climbing
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2015 RAV4 white w/98k miles and climbing - Wifes daily
2007 Prius Touring black 2/236k miles and climbing - My daily
2008 Sequoia Limited white w/135k miles(10/25/16) - Sold
2006 Tundra SR5 gray (forgot how many miles) - Sold
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post #5 of 5 (permalink) Old 04-01-2019, 06:40 AM
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Re: HVAC Issues - Diagnosis help

HiccaBurp,


We are experiencing similar problems in our 2010 Sequoia Limited. Luckily, until now, it has been a great vehicle however just thinking about the amount of work to replace the heater core makes me sick to my stomach. And like you, I don't trust a dealer to rotate my tires so they will never go this deep into it while our name is on the title. The starter has been the only expensive repair in 152,000 miles so far.


The rear heat works fine but in the front seats heat air flow is diminished if temperature setting is greater than 78 degrees. We are actually considering one of the foaming core cleaners that you spray into the ductwork behind the heater core. If it makes any difference I will let you know.


Best Regards,
Jeff

[COLOR=darkred][B]My Ride: White 2000 Tundra Limited Access Cab, V8, 4WD, TRD with 299,576 miles
MODS: [/B][/COLOR]
[B]SUSPENSION: [/B]front - Cornfed 2" lift, rear - TRD add-a-leafs. [B]EXTERIOR: [/B]Ventvisors, UTR bed liner, Reese hitch [B]ELECTRICAL: [/B]Alarm and remote start package, Prodigy Brake Controller [B]ENGINE/DRIVETRAIN:[/B]Nitto Trail 285/75/R16 wrapped around Mickey Thompson Classics. Cat Back dual custom exhaust with glass packs and 2 1/2" Stainless tips straight back. Air intake box mod.

[COLOR=darkred][B]Wife's Ride: Gray 2010 Sequoia Limited, 5.7L, 4WD, with 152,407 miles
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