Ford Expedition 99 (4X4) - It only blows out heat, even if we have it set at vent & AC sometimes only works for a minute - goes to warm air.

Any steps of direction to trouble shoot much appreciated.

Thank You

 

AC sometimes only works for a minute, do you mean you can feel it blows cold, or you observe that the AC compressor runs for a minute?

From your post, I assume it's only the temp regulation that doesn't work, and that the distribution (i.e. defrost, vent, floor) works as it should. In that case, the first thing to check is the actuator for temperature. I'm not sure if this has the same issue as the 2nd gen on the blend door actuator, but it should be easy enough to diagnose apart from getting into that tight space.

Check this video:


It's part 1, but I'm sure you can find part 2 from there.

 

I should've checked, seems he never posted part 2. Anyway, you can see the spot where it is and how to get access to it..

 

Turn the A/C on, is the compressor running, are the cooling lines cold?