Volvo climate control unit

i have dealt with volvo for a long time and i have tried but never been able to succesfully fix one so i would just bite the bullet and buy a new one

 

Not working? What exactly it does. Not cooling?

 

Wait to buy. I will find how to check you can do it. also you can find AC computer on salvage sites for penny.

 

This troubleshooting isn't right. Too many things can prevent AC start. Some of really stupid things as reverse ON switch. Usually if button is lighted means switch is ON. Not in my truck. My AC is on when switch is dark. So check with wire diagram is power get to AC computer and binary switch state.
If AC computer has buttons sticky remove the computer unplug all connectors and wash it in warm water until buttons are free. Shake the water well out use some blow air. Then submerge computer in rubbing alcohol. Shake the alcohol out blow it with air and let it dry. I did it to wash out spilled coke.
AC troubleshooting is here Help with Volvo VNL780 A/C

 

The control unit in the cab is just a head unit that tells the body computer what you want. The ecm controls the compressor after the signal comes from the body computer.

You can't fix the head unit, it most likely shorted out.

Replace it with a used one, there are a lot of them floating around.

 

Have you changed the in cab filter? If the in cab filter, mounted under the bottom bunk on the passenger side is dirty, it prevents air flow and the compressor will not circulate air. Also, if the control unit has to be replaced, then spend the $450 to have it done right and stay cool.

 

Yes it's easy to open. Just need some small stars kind tool. Clean it with some brake or carb cleaner and than with low air. Starter fluid should work too

 

Use aerosol contact cleaner.