Recently I took my cluster to get it repaired as it stopped working, but once I have done this, the AC in the car won't stop running and I'm afraid it will drain my battery.

edit: AC seems to run whenever I open the car door

 

If you are referring to the climate control module, there is a cabin air sensor that begins to work as soon as you open the door. If you are hearing a whirring noise, then the sensor is full of lint and debris. Putting a shop vac on the small grill on the climate control will pull it out enough to get the rest with a small tool and pull it through the grill. I've had a few where I had to remove the climate control module to get the stuff out.

Is this the noise that you are hearing?

 

Interesting you should mention this because my 2002 s80 will be shut down & I sometimes come outside to find the fan blowing hot air through the air conditioning vents (this happens randomly & will eventually stop). I notice the volvo does this when I'm running air conditioning & turn the vehicle off without turning the AC to OFF.

My quick remedy has been to make sure my AC is OFF when shutting down a leaving my Volvo since I'm unsure where this problem is stemming from.

 

I believe that the phenomenon that you are describing above is the after-run feature. After the car shuts down, the cabin air fan will run to dry out the evaporator core to prevent mold. It runs with the vehicle off and the key out of the ignition. Let the system work as designed. There is no reason to turn the climate control off before shutting down the car.