Plus, your hoses should be pressurized while the engine is running at operating temp...

A higher pressure means a higher boiling point (for your coolant) which is why your radiator cap will say something like "15lbs".

Disconnect your monovalve - it should provide full heat in all settings. They mostly fail by letting too much heat, not no heat, but it could be stuck or your climate control unit may not be sending it a signal. I'd check the aux pump right next to it; it's what pumps hot coolant through the heater core.

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A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.