The AC on my girlfriends 96 Civic works fine...until the outside temperature rises above about 85 to 88 degrees. At, or above, that temperature the AC will only blow hot air. Below about 85 degrees, the AC is fine and blows cold as can be. Refrigerant levels are fine, and there are no vacuume leaks. I was thinking a relay or part of the wiring might be overheating...If any one has had this problem or has any ideas, help would be greatly appreciated. Thanks in advance, Chris

 

You might want to look at the "ac radiatior." If the fins are bent, or there is obstruction on it, like paper(very common) it will not cool as efficient as it can especially when outside temps are higher.