Heater Control Valve was leaking so I replaced it. Ran the engine to test for leaks, no leaks, however the temp gauge continued to show the engine cold. When I go to rev up the engine the temp goes up to normal. When I take my foot off the gas and return to idle the temp gauge slowly returns back to below cold mark. It does blow hot air but don't know why the gauge keeps going to cold during idle, system worked fine before I changed the valve.
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1997 Ford Ranger Question: Heater Control Valve
Answer #1patrick mannion from Greg Solow's Engine Room, March 15, 2009, 21:48Master
If the erratic temperature gauge operation is only after the heater valve was replaced I would suspect there is a pocket of air in the cooling system. I wouldn't rule out the thermostat.
Replystickswya, April 03, 2013, 19:55Rookie
so HOW do you get the air OUT???