Question about 1998 Ford Mustang
'97mustang 3.8. when you turn on the a/c, the cold air blows out the defrost vents only. No matter what position the control is on.What should I look at?
Many auto cooling/heating systems use a "blend door" which mixes both
hot and cold air to provide air at the temperature selected with the
temperature control. When the temp control is in the full cold
position, the blend door moves to a position which allows only cold air
to pass into the cabin/passenger compartment.
That blend door is generally operated with engine primary [unmodified intake manifold pressure] vacuum. IF there is a leak in the primary vacuum line system, then at low engine RPM the leak may bleed off the vacuum necessary to hold the door in the cooling position. Then when driving, the vacuum will be much higher, "over riding" the leak, and allow the vacuum motor, which operates the blend door, to hold the door in the proper position and provide only cold air to the cabin/passenger compartment.
Posted on Jun 24, 2008
This never improves. There dosen't seem to be a vacume leak. engine runs smooth. Are the controls electric on these cars or do you know?
Posted on Jun 27, 2008
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