2006 LC with NAV how to get to HVAC Diagnostic Codes and cold air on "foot" setting

[ArnieC]

New to me 2006 LC with Nav and AHC (basically an LX470) - Now that it is getting cold I noticed the heater is not working properly.

Symptoms:

• Not super-hot heat from any vents
• Blows cold air from foot vents when system is set to hot/auto.
• Air conditioning works great.
• Switching modes to face - dash - defrost - feet all works just fine.
• Techstream says I am seeing 190F operating temps on scanner, I believe it because engine feels plenty warm.
• Blower motor works fine.

First question - how do I get to the heater diagnostic codes?
Second question - does this situation seem typical to anyone? Sounds like a blend door but dont want to chase my tail on anything. I am not afraid to tear into it but would appreciate some direction.

 

[ArnieC]

Update: Got the codes, with engine off have a 13 and a 21. Nothing pointing to the actuator.

Typically I would suspect blend door or motor, is the blend door easy to visually see function?

The manual makes reference to an intelligent tester and the DLC3 - any chance my cloned Techstream and Chinabay cable will do that for me?

 

[jerryb]

evap temp sensor? That solar code is garbage. I've never seen the temp sensor on the evap. First though I'd make sure that white plastic tubing is connected to the ambient sensor behind the lower panel, couple inches below the ignition cylinder.

it's funny they say,, remove the front evaporator temperature sensor Doesn't that mean remove the evap?
There's a voltage check on the A46 plug at two different temps. The bottom of page AC-27 in the book is odd.
if you want another AC amp to check with I have one sitting here. I would bet heavily that theres nothing wrong with the AC amp.
check the white tube.

 

[ArnieC]

Went out at lunch and did some digging - White tube is connected to the ambient temp sensor. Some posts on here suggested that it could be a dirty ambient temp sensor. Sensor was plenty dirty so I sprayed it down with compressed air before reassembly.

I also pulled the fuses in the drivers side kick panel to reset the A/C system. We will see what it does on my drive home.

Is there any way to view the actual data on the HVAC like what the sensors are reading and commanded vs actual position? I am used to doing this sort of stuff on a GM with a Tech II.

 

[jerryb]

techstream has AC signal on off stuff, relay checking, not sure what else. I've only used it for that. I never even looked at the thermistor page in the book before today. There is an actuator check after the diagnostic part on the buttons.
LIve data might have something. I've only looked at engine live data.

 

[ArnieC]

From the looks of the internets and what I can find, I need the Toyota Intelligent Tester to go any further without physical disassembly, some stuff is not supported by Techstream. Good news is that clones are a few hundo.

Can anyone show and tell me where the blend door actuators are so I can (try to) view operation as I run them through their ranges? Anything I can see just by dropping the glove box or is this going to be an all day, pack a lunch sort of operation.

 

[ArnieC]

Alright more digging and some updates:

• Rear heat (center console) gets hot fast - like holy crud hot
• Front ambient sensor was hooked up, I verified and cleaned sensor, no change
• Front heat is very weak, blows cold on feet all the time, upper dash vents and defrost are somewhat warm.
• All positions work during self-test.
• Still have code 13 and 21 (maybe I did not reset correctly?)
• Blend door actuator in passenger footwell seems to function normally. I can see it moving and it moves through its range of motion. I validated the shafts I can see are turning, not stripped on threads.
• Coolant is full to top of radiator cap with some left over in expansion tank.

At this point I am leaning toward a plugged heater core? Willing to take suggestions.

 

[ArnieC]

Another update:

Heater core was most definitely not blocked. With return T unhooked, get a nice flow of coolant through heater core. Flushed with a garden hose and did't see a big improvement.

Looking like dash removal time? Tips and tricks?

 

[ArnieC]

More updates:

• Heater core flush with a garden hose seemed to have made some difference.
• Now have acceptable heat out of the defrost and dash vents. Not nuclear, but not cold either.

I believe I am chasing a heater core flow problem based on the following

• Blend door operation seems correct - no codes and visually verified.
• Flushing with a garden hose made a slight improvement
• If I let the vehicle come to operating temp with the heater fan OFF and then turn the heater on, I get hot heat that gradually gets cooler. This leads me to believe that the ducting is forcing air through the heater core, but the heater core itself is not getting enough coolant through to stay hot.
• Coolant looks pretty murky but is pink

Plan is for an aggressive coolant flush schedule in the next few days and see if that improves my situation.

 

[mmcgee]

ArnieC, thank you for documenting as you chase the source. I am having the exact same issue and currently at post #7. I will try to flush heater core. Keep us posted after coolant flush.

 

[ArnieC]

My apologies - I resolved my issue - mainly a bad thermostat and poor job refilling leading to air pockets and started another thread on it.

Short version:

Flush, flush, and flush some more. Cover your starter or extend the hoses to the core to keep from getting a bunch of water in the V of the motor.
New OEM thermostat from the dealer, PO had put in an aftermarket one and it was not correct for the application.
Fill the system using an Airlift or similar to eliminate any air bubbles in the core since it is the highest part of the system.
Make sure your radiator cap/overflow tank is working properly, levels adjust during operation. If your radiator cap is not holding pressure and the level in the radiator is low at all when cold, the system will always run low on coolant.

When your rig is 100% cold and you open the radiator cap, it should take no more than a few tablespoons of coolant to overflow the radiator. Any more than that and you have either a bad radiator cap or a leak somewhere in the coolant system.

 

[mmcgee]

Thank you. I found your other thread after posting here. I will check my cap, flush and replace my thermostat.

 

[Jimi900]

Thank you. I found your other thread after posting here. I will check my cap, flush and replace my thermostat.

What thermostat are you referring to? I also have the problem and have done most of what you have listed without any positive out comes..