My actuator is bad and my a/c won't blow cold air

You have actuators which direct the air in the heater/vent/AC system. My first cars used metal cables, then came along vacuum line control and most now use electric control actuators. They control things such as how much air from outside the car come inside, air flow to windshield/floor or dash, control mix of air for temperature adjustment. Your problem more than likely actuator issue. You can try google vehicle year, make, model temperature different from ac vent, when search you can change wording. If vehicle is older and used vacuum lines could have line leak, my 2000 GM van once had vacuum line laying on engine melted line and leaked. My 13 Chrysler, I have changed 2 actuators they are controlled by electric and started clicking when they went bad.

DODGE DART, CHRYSLER 200 CAR BLOWS HOT ON DRIVER SIDE COLD ON PASSENGER OR COLD ON DRIVER SIDE - YouTube

You have heater valve problem ,see if the valve open and close ,all the best.

Couple of things come to mind. You have climate control, so it could be that the temperature sensor is bad or the plenum door actuator is bad. I would lean more to the sensor, as the door usually is open or closed when it goes bad. This would leave you with cold or hot all the time. Also the climate control console could be bad. You can have this checked with a hand held computer.

Your brother's mechanic may be correct but you may want to double check if you have a bad flap which opens / closes the access of coolant thru your heater hoses to your heater core. This component is called an actuator which may be defective.

On the central console is the A/C module. Inside A/C module are driver's side & passenger's side air flaps for mixing hot & cold air and directed air flows towards driver's side & passenger's side according to driver commands. The passenger's side flap for mixing hot & cold air according to driver commands is bad. Flaps are actuated by electrical step by step motors. Could be damaged the flap actuator (motor), the flap mechanism (blocked in "HOT" air position), and / or electrical supply wires. You must access the passenger's side flap for mixing hot & cold air, and see what happens when you command cold air to the driver's side: flap mechanism, flap actuator, supply wires, ... Repair & replace bad pieces and test the A/C system.

The vent actuator my need to be reset, this can be done by removing the HVAC fuse from the fuse panel for 5 min or disconnecting the battery. If the vent actuator does not correct it self, then it's most like going to have to be replace due to internal parts have broke in the actuator.
Thank you for using fixya and it's common for the vent actuators to go bad after a few years, the internal parts are made of plastic and get brittle after time.

Bad rear blend actuator.

may have a bad blend air door actuator.

There is a flap that directs the air. the flap is controlled by a vacuum actuator. This is located inside the venting. The actuator is connected to little vacuum hoses that attach to the temperature control switch. Either the flap is stuck, or the actuator has gone bad.

You have dual zones that are controlled by temperature actuators the passenger side has lost its memory or has gone bad you can put it in self programming by disconnecting the battery for ten minutes then hook it back up start the truck turn the temperature control on but do not touch any other controls let it go thru the self programming for about 6 to 7 minutes then select your temperature you want if it still does not work properly you may have a bad actuator or a bad connection at the actuator