My 1996 Windstar, V6, 3.8L, stops blowing air from vents
intermetiently. When I turn AC or heat on, the vents blow air
fine according to the fan speed setting. But after 10/15
minutes, the air flow decreases significantly or stops
altogether, no air comes out of the vents, yet I can hear the
blower fan noise as if it is working and feel heat/cool at the
vents (as per the selected setting). I have tried changing the
selecter switch from AC to MaxAC, dashboard vents, bottom vents
defrost, or fan speeds, but nothing works; It stays the same
whether the vehicle is moving or is parked. The air starts
flowing normally after half hour or so, or the next day.
I replaced the HVAC Vacuum Selector Valve (behind the controls)
last week with a new one made by MotorCraft and it did not make
any difference.
First thing that comes to mind is vacuum leak. Given the
intermetient nature of the problem, I was wondering if this
really is due to a vacuum leak?
Next I thought of the blend door actuator, which is a common
proble with Windstars. Since it does not default to hot or cold
air, could it still be a blend door actuator problem?
I am looking for help to pin point the problem and would
apreciate hearing any past experiences dealing with such an
issue.
[Reply]
Does it come from any of the vents? From your writeup, it sounds like you aren't getting any airflow anywhere? I can't say I've seen that problem before.
I take that back. I've seen a similar problem, but it was in a Chevy van. The A/C would get so cold that the evap. would ice up and you'd slowly lose airflow until it stopped completely. The only solution we found was to turn the heat on for about 1 minute and it melted the ice. It took about 30 minutes for the ice to accumulate to the point that it would restrict airflow, so it was a suitable fix rather than a teardown.
You might try that.
Mark
[Reply]
Mark, thanks for the suggestion.
The air flow appears to be decreasing gradually until it comes to a complete stop and then it gives no air from any vent, even if I change the speeds, heat, or dash/defrost/bottom outlet settings. I have always had this problem when the AC is on, except one one winter it happened when the heat was on... It was a stormy day, icy all around, and perhaps I must have one of those heat/vent settings (e.g. defrost) where AC runs along with heat automatically in the background to remove moisure.
Anyhow, I like your suggestion and will try it out and let you know.
[Reply]
I just followed mark_gober's advice (see post above) and kept vent settings where AC would not come on. If I am not mistaken dual flow settings and defrost settings are configured to turn the AC on in the background to suck the moisture out of the cabin air. This is explained in the owner's manual. The problem did not reoccur and I did not want to spend time diagnosing it further.
A couple of years later, I did have to replace the compressor cycling switch on the AC accumulator/drier as the AC stopped giving cold air. I don't know if this was related to the problem, or not.
[Reply]