The famous volvo climate control horror,-siberia cold or blacksmith forge hot and nothing in between.
Bought my volvo last summer and drove it 1400 miles home.
Climate control on max heat, no response using the temp control ****. Had to do the whole trip with windows open.
A nice throbbing chopper sound all the way home.
-Nice!

Then came winter with temps down to negative 49 and below.
Usually the climate control has been max warm, but occationally it would decide to blow max cold.
-Even nicer.

Last night I decided to give troubleshooting a go, so I removed the panel in the footwell and to my delight I saw that the control arm had fallen off the servo motor.
The door moved real easy, which explains why it would suddenly blow cold at times.
Riding over a bump or accelerating/decelerating can obviously make the door move if the control arm is not attached to the motor.
Put the control arm back on and now the temp responds to the control ****.

No need for pulling the dashboard, buying a used c-c unit or upgrading software at the stealership.

 

Glad you got it working with no expense. Better late than never.