W150 1/2 Ton Pickup 4WD L6-225 3.7L VIN E 1-bbl (1982)
Power Heat Control Valve: Testing and Inspection
1. Disconnect vacuum line from power heat control valve.
2. Connect a suitable vacuum gauge to the valve and apply 6 inches Hg to the valve. The valve should be fully closed. If valve is not fully closed,
replace valve.