1st Gen. 2002 A/C Issue

Hello!
I have a 2002 SR5 Tacoma that has an odd A/C issue.
The A/C works fine blowing cold air, but at times will start blowing hot air.
I twist the center temperature control dial (see photo) over to the warm air - red side, then back to cool air - blue side.
I'll do this 2-3 times and it starts blowing cold air again.
What would cause this?
I did a bit of checking on YouTube, and it appears there is some controller board that these 3 panel dials attach to. Would that be the culprit?
Was just checking to see if anyone has experienced something like this and if so, what they did to remedy the issue.
Any input much appreciated.
Thanks!

 

As far as I can tell, the Air Mix control is operated off of resistance at the dial.
A pure guess here, but I'm betting the dial is loosing connection and defaults to heat.
Heat is usually the default setting. You have to have heat. You don't have to have AC.

There Air Mix servo could also be going bad. My manual doesn't have diagnostics on it. (testing) Maybe @Dm93 knows the procedure.

 

Thank you TnShooter!

 

Took me a bit of digging. But I found the test procedures.
As expected, the dial is resistance based. Toyota has you check it by voltage.


Next, See where the Air Mix arm is when this happens

 

Thank you again for the help! Much appreciated!

 

Just changed my broken air mix servo and heater control valve. Valve wasn’t closing all the way so hoping that ‘may’ have been why my ac wasn’t blowing super cold. Anyway, here’s a great YouTube video for the servo removal and testing. A lot of detail.

https://youtu.be/yRRcLVNqgC8?si=PJGxnLulIVQoGDRc

 

So does the compressor turn off and on or does the compressor stay on all the time when this happens? If the compressor is low on freon it will cycle off and on blowing non cold air when this happens. Are you low on freon?

 

I think don’t know that the servo just controls the heater control valve. My compressor works fine and was topped off w Freon. But if hot water is flowing through the heater core via the bad valve it’s my guess/hope that was why my ac wasn’t blowing super cold. But it’s only in the 60’s so won’t know til summer.