I have two AC Units. One for upstairs and one for downstairs. The upstairs one works just fine but not the downstairs. So, i did a test by turning both units on and went outside to compare the two units. The upstairs one works fine and blows out warm/hot air, but the downstairs one seems to blow out cold air compare to the working unit. These two are not heat pumps. They are both AC units. Anyone know what is wrong with my downstairs unit?
BTW: I had the HVAC guy come out to check it 3 years back, and he added refrigerant into the system. It worked for a week or two after he left, then it's back to warm air again. Would this be a leak of some sort?