2006 Rear heater vacuum acutated valve malfunction

[delgriffith]

I've got an E-250 that has aftermarket rear heat. I can locate a vacuum operated coolant control valve for the rear heater under the van, just below the driver's seat. One day it was only giving heat, another day it was only giving cool regardless of the temperature control setting. (the aftermarket system just works off the standard front temperature control) I checked the vacuum line and one day it had full vacuum, the next day none. So I don't think there is a vacuum leak. Seems like maybe an electrical issue in whatever controls the amount of vacuum applied, but I'm not sure. The front temperature control is just fine. Any ideas?

Thanks,
Dave

[BroncoJoe19]

If you have no vacuum , you have a leak in the line that goes to where you have no vacuum. The switch may actually be a vacuum switch, and it may be faulty and leaking.
I have some pictures in this thread.

WIndstar rear heat issues
http://www.ford-forums.com/ford-wind...html#post55494

This thread may be helpful too.
Econoline Rear Heat A/C How To
http://www.ford-forums.com/ford-econ...tml#post131707

[delgriffith]

It did not seem like a leak, because the exact sequence of things were:

Day 1: heat stuck on, checked vacuum line and felt nothing.

Day 2: no heat, checked vacuum line and felt good steady suction, and attaching it closed the coolant valve.

Day 3: heat stuck on, no vacuum again.

So because of the intermittent-ness I would not expect a simple leak....