About a year ago I bought a Fujitsu Hi-Wall Air Conditioning Model AOB18R1 (Cond) and ASB18R1 (Evap). The guys who installed forgot to plug one of wires and at the beggining the heating worked for 3 minutes and stoped for 3 minutes as a protection for hi-pressure caused for the missing wire. After a week the same guys who installed came back found out about the wire they forget to connect and everything seemed to be fine. But I noticed that doesn't matter how high I set temperature for heating the air conditioning works fine for about one hour and after that it blows a cold air at low speed for 3 minutes, this is a pain in the ass, because when the environment starts to get warm, the cold blow air starts ruining everything.
I am sure the environment is not overheated because I have thermometer inside that shows me the exact temperature, which is not higher then 71F/22C degrees.

Can you guys tell me if this is normal or what kind of problem do I have.

Thanks