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Heat Only Coming From Driver's Side, But A/c Works On Both Sides


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Hey all. I've been googling this issue for 2 days with no fix. I'm close to spending the money to get an rx330 service manual.

My issue -
Since last winter, the darn dual climate control will only put out heat on the driver's side vents on any warm temperature setting(above ambient), passenger side will only put out room temperature air. Cold A/C will come out of both sides just fine.

AC diagnostics check says code 11, which I've read to be the temperature sensor circuit. I tested the sensor by the knee on the driver's side and resistance goes up and down with temperature, within ranges that I've seen for other thermistors--this one read 1.68 kohm last night. I checked the connector and read 3.5volts going to the sensor. Sprayed in contact cleaner and reconnected it. Still the same error.

Are there two cabin temperature sensors in this car?? if so, where is the second one?
It seems like there is a second sensor on the passenger side that thinks the cabin temp is high so it doesn't allow the air mix control to allow hot air through.

My second theory is that the air mix control servos aren't working on the passenger side. I don't know what servo I was looking at but I could peek a servo moving up and down on the passenger side left knee area under the dash. it would move up and down as I changed temperatures.


One last thing to note - i take it off dual climate control and the problem remains the same. My thinking is that the dual climate control off would mean it uses the one temperature sensor to control heat to both sides of the car.....

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I had the same problem. I went my local mechanic who is good and he cleared the codes and reset something and now I have heat.

I also read a thread on this that stated there was dust or something on sensors / or they need to be replaced... Good Luck Fall is here

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I had the same problem. I went my local mechanic who is good and he cleared the codes and reset something and now I have heat.

I also read a thread on this that stated there was dust or something on sensors / or they need to be replaced... Good Luck Fall is here

Hmm. Maybe I'll try disconnecting my battery and see if there are any codes I can clear. Otherwise I'll be tearing into the dash soon.

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If you go to www.techinfo.toyota.com

you can get repair manuals, service bulletins and wiring diagrams for $15 (2 days).

A quick Bing search revealed a similar question concerning a 2006 RX330. It was answered by a Toyota Master Diagnostics technician who identified the likely source as the AC heater box and one of its door controls. According to him, the box is not serviceable and would need to be replaced. Apparently, the dash must be removed to access it.

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Thanks. Techinfo was my last resort if I couldn't find answers on here.

I did read that question /answer but there was no definitive answer so I shrugged it off. They didn't even get in depth with the diagnosis.

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Update

I ran across something that said it may be a clogged heater core so I flushed and backflushed the heater core with some vinegar and water repeatedly. water looked clear so i think it's good.

It seems like the airmix control servo isn't switching but I can see a servo moving up and down as I change the temps on the passenger side.

Can anyone confirm which servo is the airmix servo? I looked at the parts diagram and it shows that there are two servos on the passenger side. I can only see one so maybe i'm only seeing the mode control servo.

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  • 1 year later...

Hey all. I've been googling this issue for 2 days with no fix. I'm close to spending the money to get an rx330 service manual.

My issue -

Since last winter, the darn dual climate control will only put out heat on the driver's side vents on any warm temperature setting(above ambient), passenger side will only put out room temperature air. Cold A/C will come out of both sides just fine.

AC diagnostics check says code 11, which I've read to be the temperature sensor circuit. I tested the sensor by the knee on the driver's side and resistance goes up and down with temperature, within ranges that I've seen for other thermistors--this one read 1.68 kohm last night. I checked the connector and read 3.5volts going to the sensor. Sprayed in contact cleaner and reconnected it. Still the same error.

Are there two cabin temperature sensors in this car?? if so, where is the second one?

It seems like there is a second sensor on the passenger side that thinks the cabin temp is high so it doesn't allow the air mix control to allow hot air through.

My second theory is that the air mix control servos aren't working on the passenger side. I don't know what servo I was looking at but I could peek a servo moving up and down on the passenger side left knee area under the dash. it would move up and down as I changed temperatures.

One last thing to note - i take it off dual climate control and the problem remains the same. My thinking is that the dual climate control off would mean it uses the one temperature sensor to control heat to both sides of the car.....

Update

I ran across something that said it may be a clogged heater core so I flushed and backflushed the heater core with some vinegar and water repeatedly. water looked clear so i think it's good.

It seems like the airmix control servo isn't switching but I can see a servo moving up and down as I change the temps on the passenger side.

Can anyone confirm which servo is the airmix servo? I looked at the parts diagram and it shows that there are two servos on the passenger side. I can only see one so maybe i'm only seeing the mode control servo.

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