Re: Temp knob causes temp guage to spike
If the cooling system has never been serviced (flush & fill) I'd say its time to do that and replace the thermostat. If the temperature doesn't go too far below freezing, a 180F stat (195F stat is stock) may be a better way to keep temps in check. Normally with the heat setting on high and the fan setting on high the engine temp will lower slightly due to the cooling of outside air passing through the heater core and blowing into the cabin. Worst case is that the blend door is not aligned properly (it's vacuum actuated), which can be a major job to repair...but I'd stick with the coolant service and T-stat change.
'11 Ram Quad Cab 4x4 SXT 5.7L HEMI (stock); 48,500m
'06 Pontiac G6 GT 3.5L 220hp; 64,000m
'12 Chrysler 200 Limited 3.6L 283hp; 28,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!