Need help. 2006 GX470 w/nav. Heater will blow hot for about 5-10 minutes then start blowing cold. No issues with the Cold A/C. So occasionally I hear the clicking from under the dash which I assume is the actuators. I have not changed them yet. But I ran the a/c diagnostics at dusk outside and came up with codes 21 and 24. I saw the code 21 as a solar sensor I will try when again when it’s sunnier outside. But I did not see a code 24 on the code list. Does anyone know what that code is for? Thanks.

 

Hello,

What do you set the temperature to when the issue occurs?

Turns out there may be two solar sensors in the car, on Driver and Passenger side, Code 21 is for the Passenger side, Code 24 is for the Driver side. Those codes likely don't mean much, since they can appear at random in dark environments.

Try setting the climate to Max Cold or to Max Cold, which will force the Climate control to fully open or close the blend door, and inspect the actuators as well as their arms, see what happens. If the actuator is stationary for a moment, try taking it out and cleaning it from the inside.

Hope this helps and best of luck!

 

When the heat is on, it’s on MAX HOT. It will blow hot for a few minutes and then start blowing cool to cold. Almost like the temp is going from max hot to max cold one one degree at a time. Could the actuators be causing that?

 

Try leaving the climate in Max Cold or Max Hot setting for a little while and see if it will start doing the same "drifting". If so, it is likely some mechanical failure with the blend door or its actuator, if not, it may be one of the temperature sensors, like it is described here.

Hope this helps and best of luck!