papaindigo wrote:
nursecosmo - if I am reading your comment correctly during your drive yesterday your temp gauge stayed just left of center but you had little cabin heat except on recirculate; correct? When on recirculate did you have plenty of heat? Coolant is supposed to flow thru the heater core at all times absent an air lock, so to speak, in the heater or a plugged or partially plugged heater core. How much heat you get is controlled by the blend doors in the AC/heater box. If you had a good temp gauge level you should have decent heat input to the cabin unless:
1. there is air in the cooling system which can, apparently cause cylinder head problems. You might consider on a cold engine pulling the front end of the heater hose that runs from the viscous over the top of the tstat to the heater to see if it and the viscous are full of coolant.
2. with the engine hot see if the in/out heater core hoses are the same temp or nearly the same. If there is a big difference I'd suspect a partially clogged heater core which maybe can be reverse flushed gently with a garden hose applied to the heater core return line (i.e. the one that does not go to the viscous). If both lines are hot and about the same temp I'd suspect you have a blend door control problem especially if you get good heat on recirculate but not on the heat setting.
Check those out before considering an in-line. An inline with a good factory tstat might do a bit of good if you get a "hotter" in line (say 195F). Of course if I'm reading you wrong and your temp gauge was not near vertical yesterday that's a different story.
I don't think it's any of those things except perhaps a blend door malfunction. When -20 degree air is coming through the heater core from outside it can only pick up so much heat from the core. If the heater core warms it up by 50 degrees(I don't know what the rise should be), that is still below freezing. I don't think it's a blend door issue because if I put it on recirculate, it will not immediately get warm but will keep reheating the cabin air and eventually the air coming out the vent is warm. I'm not saying that the heat coming out of the vent from outside is cold but it just isn't enough to warm the cabin enough for comfort. It never has been really warm in extreme winter cold even when new and I wouldn't mind raising the temp a few degrees with a 192 degree thermostat.