Could this be my issue also? I have a perfectly functioning monovalve (I double checked this) and I still only get mediocre heat with the fan above a low speed. On low its nuclear hot air drifting (fan speed 1) from the defrost/floor/side vents depending on the setting, but when I increase the fan speed, the air cools off to a "lukewarm to cool" temp. My only guesses are a flap issue, or heater core plugged up? My aux pump has been squealing and begging for death....so I will change that out tomorrow when I replace my thermostat....we'll see if new t-stat (my temps are about 8-10C low right now) and aux pump solve it. If not....what should I look at next?

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