2013 T4R SR5 weird heater control

[GettinOld]

Hey guys, I hope you can figure this out. I have a new '13 SR% with manual climate control. When the fan is on (regardless of speed), heat is on and I turn the temperature control knob to max heat (all the way to the right) and the fan dims somewhat. If turn the temperature control knob to the left a bit (towards cool) the fan goes to the proper fan speed? Is a little delay when this happens. Usually the tempearture control knob only controls the temperate. In this case, it is controling the fan speed a bit. Again, only when the control knob is all the way to the right? Has anybody have the same issue? Is this normal and why?

Thanks!

 

[1engineer]

On the temperature knob, all the way CCW is MAX cool and the system goes to recirculate and the fan goes to max. Turn the knob a little CW and the fan speed drops to whatever the fan speed knob is set at and the temperature is now on just cool. Continuing to turn the temperature control knob CW will not change the fan speed but will increase the temperature towards hot. This happens no matter where the fan speed knob is positioned.

 

[GettinOld]

Thanks for the post and yes I understand in that circumstances... However, I'm talking about the opposite...

1. Turn your fan on max
2. Turn the middle control to def/floor air flow for example
3. Turn the temp control to max heat (CCW so the indicator is at the RED square)
4. Note the fan speed and air flow sound.
5. Now turn the temp control CCW a couple of notches and wait a few seconds. The fan speed should increase.
6. Put the temp control CW to max heat again and your fan speed will decrease.
7. Go back an fro and see the difference.

Try and see if your T4R does the same.

Thanks

 

[harper7]

My best guess would be that when you have it on full heat it is bringing air in across the heater core and has less volume of air(smaller opening) to suck from,thus lowering the fan speed.

When your opening the switch(less heat), it is opening a door to mix the air,either from outside or from within the truck depending on the position of the recirc switch and you have more have more volume of air available to move,thus letting the fan speed go up to it's max speed.

You just have to think of what the heater/ac switches are doing ,which is opening and closing doors in the duct work of the truck to where it gets it's air from and mix it to get the desired temp..

 

[j_shoe99]

My 2012 SR5 does the same thing. After you turn the heat all the way up, a few seconds later, it sounds like the fan slows down.

I've never noticed that before...oh well...no biggie to me...:cheers: