My heater is acting up. Sometimes it heats up fast, sometimes really slow. There are also instances that it blows hot air and it will blow cold air all of a sudden. My water pump was just replaced and the coolant was just flushed. Any ideas?

 

Check the block sensor and coolante sensor

 

Do you have more detail on this?

My girlfriend's heater is having similar issues. She has an '05 with quite a few miles on it. She says the heater blows hot air when the car is moving, but blows nothing but cold when slowed down or at a stop.

Any ideas? She doesn't have a lot of money, but I would like to get this handled for her before it gets too cold here in Ohio.

TIA!

 

You guys can try running the diagnostic and see if that tells you anything:

https://acurazine.com/forums/showpos...23&postcount=2

 

^What does that diagnostic do? Could you please enlighten me. Thanks.

 

I'm having the SAME EXACT issues the OP stated his GFs TL is having. I am blessed to not me short on the money end so I am headed to the dealership this morning to hang out with my buddy (Shop foreman) so we can see what the crap is going on. Ill post results.

Jesse

 

Thanks. Please let me know what you find out.

 

My buddy checked out all of the sensors. I had a CRAP load of dust on the cabin temp sensors, which totally explained why the Auto Temp was sucking so bad. I was puzzled about the stop light, turning corners, and occasional cold times in the car. As the car moves and turns the air also moves around in the car, but the sensors were not sensing this. We took a like pressure air chuck and dusted them off. It was as comfortable as radiant heat in a house all the way home today. I am sure there are a few different reasons why heat goes cold, but this took care of mine.

 

^ I noticed that my car blows off hot air when im driving but blows cold air when i'm idling. Where are those cabin sensors located?

 

Well we knew that the Amb TS was good as it was accurately reading the temp outside of the car. So we went through the whole system checking things off. Interior temperature sensors, outlet duct and evaporator temperature sensors, pressure sensors, humidity sensors, blend door position sensors and sunload sensors (for A/C system primarily). There’s even a GPS that allows the control module to determine the vehicle’s orientation to the sun so it can increase cooling on the side facing the sun and decrease cooling on the shaded side. I rest my Navi unit for that one.
The Hose and aspirator for the humidity are on the driver side and there is a sensor in there. It sucks in air and senses temp change as well.
Since most of my problems were coming from the 'Smart' Head rather than the 'Dumb' Head of the ATC system we also looked at the sensors that tis system uses only. So we know that temperature sensors have a “negative temperature coefficient,” which means they lose resistance as the temperature goes up. A simple way to check this type of sensor is to use a heat gun (on low) to heat the sensor. The resistance should drop as the sensor warms up. Keeping this in mind we took the two outside temp sensors into consideration. The one behind the bumper and the one in the intake. Well they were functioning.....but how well. Yes we were getting an accurate readout, but then we remembered that the car can monitor the air temperature when the vehicle is moving. Seems simple I know. Going deeper....mbient air temperature sensors typically have a slow sample rate to even out variations in readings that may be sensed at different vehicle speeds. When the vehicle stops moving, heat can build up quickly around the sensor. This could mislead the ATC module into thinking it was getting hotter outside. I am not positive, but I think the newer TLs ignore the ambient temp sensors when they are not moving, not sure.

Anyway, we cleaned those sensors.

I cannot tell you which one took care of the issue, but it is all gravy now. Wife is happy and that is really all that matters

 

Oh, sorry forgot to specify. Sit in the driver seat. look down at your right knee. then look at dash cover just above it. Those little slits are where the air is sucked in.

 

If it's the sensor it should be cured by not using the auto function and turning the heat up as high as it will go.

The most common cause of cold when stopped, hot when moving (well actually engine rpms above idle) is low coolant level and air in the system. I wouldn't be surprised to see the issue return unless you never tried turning the heat all the way up without it in auto.