2009 Ford Ranger. Blows heated air when AC is turned on. No vacuum to heater valve just as is the situation when the heater is on. Vacuum work properly other than when AC is turned on. Any idea what could be the cause of this?

 

Hard to follow what you are trying to say. First step, make sure the compressor is running.

 

Yes, the compressor is running. The lines are cold as well. everything seems good except for the heater valve not being closed by vacuum. When the AC is turned on, the compressor works properly but the heater valve does not remain closed by the vacuum system. With this being the case hot water is running through the heater core and therefore the air from the AC is being heated. When everything is turned off, vacuum does close the heater valve as it should.

 

If you actually verified that vacuum is present at the valve but not at the correct time when the a/c is on, there has to be an issue within your dash with the control head. My father had that same issue with his Ranger long ago.

 

Thanks for you reply. This is exactly what I was thinking as well. I have ordered the control switch. (It is not scheduled to come in until about April 1st). I will replace it and see what happens then. I will post the results when I get the part installed.

 

Update ! Changed out the selector switch ... no success. But, I did discover that the AC works when Max A/C is selected. But, the blend door stays wide open. Even with heat, the temp can not be changed, It blows HOT at all times. Summary = blend door does not work, vacuum works at the heater control valve properly when A/C set to Max A/C. Did not change the temp selector switch. Will do that when I can find one.

 

Maybe it's related with the control head?

 

Thanks for the reply. I have compared the operations on this vehicle to the operations on another similar (much the same) vehicle. I have found that I have looked at the wrong situation. The vacuum system seems to be working as intended. It seems like the issue is actually with the blend door. The door appears to be in the open position. With the heat on, I get full heat even when the temp control dial is in the cold position. The temp does not vary. I hope it is just a bad actuator and not an issue with the blend door being stuck/damaged. When the temp switch is moved, there is no sound coming from the actuator and I am getting proper voltage to it. I will change out the actuator when I get it and post the results.

 

Problem solved. It helps to address the issue from the correct "angle". Blend door actuator was the problem. I was looking for another reason for the hot air and not thinking that the blend door might be stuck open. The actuator was bad and therefore kept the blend door open to hot. I replaced the actuator and everything works properly. Thanks for the replies and suggestions.