heater
2 Answers
Could be stuck water valve, vent flap issue, or the CCU unit. The water valve can get gummed up. Some people have had some luck taking them apart and cleaning. Has the cooling system been flushed in the past few years? If not might be time for that. Only other suggestion is the thermostat itself but you did not mention if the engine temp gauge is getting up to proper temperature or not. Good Luck!
Hornet_2497 answered 5 years ago
Top up your coolant level in both the radiator and the coolant overflow bottle. Also test coolant freezing point to make sure it is not slushed up and can't circulate.