This must be a common operation. I had an independant mechanic in Knoxville recommend this, which I did. Works great. You can regulate your heat via the valve by patially closing, as the weather warms. My cost of the valve, a length of copper tube and hose clamps was about $4.00, sure beats $800 for a new servo.

Do not remove or unplug the servo, as it also serves some purpose in the A/C unit, or so I am told.