Should be accessible from the driver's footwell. Find the two steel 1/2" lines coming thru the firewall and trace them to the first turn upwards and you should find the water valve there. Disconnect the control wire and see if the lever frees up. If so, try to force the water valve loose. If not, try to readjust the wire.

You get heat/air flow because unless the air source select lever is on recirc, the air pressure from truck movement forces air in. It's always open.

Last edited by fasteddy; 02/11/14 04:56 AM.
Not responsible for advice not taken...