Ive had this problem with my air conditioning for a while. only the left side and bottom vent blows hot (like the heater is on high) and middle blows nice and cold??

Ive been told that It's probably the water valve (monovalve or duovalve). But still not sure. Id like to avoid taking it to a shop if possible. If someone could help me, that would be great!

post here or email me at: jesseworld@helloworld.com