Air Flow Problem
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Junior Member
Joined: Feb 2008
Posts: 3
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From: Jacksonville, Ohio
Air Flow Problem
I have a 1999 Expedition with heater Air flow problems. When I first start the cold engine I can select airflow to any position, floor, defrost, vents and get a lot of air flow. But as soon as the air gets hot and I move the selector to another setting such as from defrost to floor or vents I loose all air flow to all positions. I can hear the blower blowing and the sound goes up and down as I move the speed but no air flow. I believe the blend door is working because I can make the slight air that I get cold or hot. I also do not get any airflow in A/C. If I leave the selector in the position I start with when cold I keep air flow in that position but as soon as I select any other position I loose all air flow???? 
Rear Heater/AC works great.
Rear Heater/AC works great.
Last edited by hummermech1; Feb 14, 2008 at 01:38 AM.
Senior Member
Joined: Oct 2002
Posts: 7,295
Likes: 125
From: St. Louis (Out in the woods)
Verify that the airflow is not diverting to the defrost.
If not, test the system by leaving the system only in the VENT position while the engine warms up. Determine whether the airflow reduces in this condition at warmup. If not, your evaporator is icing up.
Reason for selecting VENT position is that it does not turn on the compressor (FLOOR position is the same) and will not induce an icing condition should that be what has been happening.
Steve
If not, test the system by leaving the system only in the VENT position while the engine warms up. Determine whether the airflow reduces in this condition at warmup. If not, your evaporator is icing up.
Reason for selecting VENT position is that it does not turn on the compressor (FLOOR position is the same) and will not induce an icing condition should that be what has been happening.
Steve