Mechanics

WARM AIR BLOWS OUT VENT ON ALL SETTINGS BUT MAX AC

Ford Explorer

I have a 1998 Ford Explorer 4.0 EFI with 120K miles. For a while now, warm air blows out of all ac/vent settings but MAX AC. When on the MAX AC setting, the AC works good. I have replaced the heater control valve but still the same. I have also compared the hoses to the heater control valve with an Explorer that works and they are at the same places. When on MAX AC, the heater control valve engages and cold air blows out the vents. When on AC or a vent setting the heater control valve disengages and warm/hot air blows out the vents. I suspect a vacuum problem but don't know where to look. Any ideas?
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Mstevep
June 3, 2007.



It has a manual temp control. Where is the blend door located?

Tiny
Mstevep
Jun 5, 2007.
The fuse (10) is good. With the test that you suggested I heard only the blower motor at either full cold or the full hot setting. No clicking or whirring, just the low sound of the blower motor turning that occurred when set to floor blower. No change in sound or different sound when changing from full cold to full hot or visa versa. I listened for about 30 seconds at each setting.

Tiny
Mstevep
Jun 10, 2007.