Weird HVAC problem
 

I have quite a strange problem. I have a 95 XJ w/ 2.5l w/ Air Conditioning.

Lately i noticed that there seems to be fresh air coming out of the defrost and main air vents intermittently, even when the heat is not on. When the heat is on, it intermittently blows cold air out of the top vents while the warm air from the heat blows out the bottom vents.

The AC, vent, and even the heat work great though.

If the engine is idling and i turn the heat (from the off position) the engine bogs down for a few seconds and then returns to idle. The same thing happens when the heat is on and i turn it off.

I have checked all the vacuum lines coming out of the intake manifold and they all hold vacuum.

I replaced the 3 actuators under the dash and and checked the vacuum lines that go to the actuators. They all held vacuum.

Does anybody know what this could be. What controls the vacuum going into the actuator? There has to be something that takes the electrical signal from the switch opens or closes a valve in the vacuum lines, right?

Any help would be appreciated.

thanks