ac works under 50mph then heater turns on after 50
Hey guys its been awhile since I posted but here is a brief rundown of this weird problem on my 1995 4 banger.
a few weeks ago my heater control valve was leaking and replaced it with a motorcraft one. easy to replace but i noticed later that under 50 mph my ac blows cold but over fifty it starts blowing hot air so i turn it off to cool the compartment. well the heater on the floor vents keeps blowing intermittenly while i am traveling on the highway. In Texas the heat is above 110 degress, so u can imagine the heat inside the cab. I have checked the blend doors and vacumn lines and they seem operable and working. What can be the problem. Does she not love me any more and is making me suffer in this Texas heat.