SOMETIMES but not always, when it's hot outside, the AC doesn't cool, but I must stress, only sometimes. Other times it works really well.

SOMETIMES but not always, when it's cold outside, the Heater doesn't heat, but I must stress, only sometimes. Other times it works just fine.

I don't know anything about the Climate Control in my SR5 and wanted to know if anyone else has had something similar happen to them.

I hate to take it to the dealer and turn the truck over to them without some idea on what's going on ! !

 

You don't have the digital climate control, do you?

 

Nope

 

Ok here is my Theory:

Usually when the heater blows cold air intermittently, it is because of air pockets in your cooling system. But since it happens on the Air Conditioner mode also, it can't be that. I think that your climate control system is electrical (whereas mine is mechanical), it could be that there is a short, or one of the contacts is either dirty or shorting out.

There is my $0.02

 

Would certainly be the route I would take to diagnose it.
I think the twist knobs were when they went electrical.

Mine looks like this (with the mechanical slide actuators):
You can "feel" the ducts moving so you could easily tell if they were not closing/opening properly.