Windstar rear A/C problem

I have a '98 Windstar with rear air. The rear air now blows out of the floor as if it is on the heater selection and is intermittently blowing hot air also. This happens regardless if the front control is
selected or the rear control.
Can anyone out there tell me what to look at replacing first? I am competent enough to go to the dealer and get the part and replace it myself. It looks as if I can get to all the electronic gear by pulling the side panel off. I really appreciate any help.
Rodney Hyde
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Rodney,
I had a similar problem recently in my E150. While I was underneath the chassis replacing twenty feet of heater hose I discovered a valve that controls the water flow to the rear heater coil. It is controlled by a vacuum line. That vacuum line had deteriorated and rendered the valve ineffective. Consequently, hot water was always flowing through the rear heater coil regardless of any environmental control selection.
The repair of the vacuum line also seems to have remedied the premature step-down of the A/C whenever driving uphill.
I would suggest you chase your rear heater hoses until you find a vacuum operated valve.
Rodney Hyde wrote:

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Had a similar problem and it was a broken vacuum line. If you only have air venting from the window defrost no matter what front vent selection you make than it is a vacuum line, this is the default vent position. My break was under the hood right in front of the passenger seat, I was told by a mechanic that that is the most common break area. There is a vacuum line that comes off from the back of the engine and runs to the right side of the van (when looking from the front) it connects into a three way connector. One of the connections goes into the large black container on the passenger side the other goes into the firewall. The only problem I had was feeling around behind the container as I couldn't see were the hose went onto when I had it off, otherwise it was easy took 15 minutes to fix.
Hope this helps.
Peter

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