Q: Weak heat in all vents, cold air comes out of drivers. 2008 Jeep Wrangler

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A couple of days ago i noticed on really cold mornings 30 degrees f and lower, my heat does not work well. When its 50 or warmer out it works good. The driver side vent remains cold all the time. Replaced thermostat, it opens properly at 195. Flushed system and new coolant is full. All hoses get hot and seems to have good flow. Why do i not have heat?

My car has 100000 miles.
My car has a manual transmission.

Hi there - I believe you have a problem with the heater air blend doors. As you know, the lack of heater function could have 5 causes: the engine is not getting up to correct temperature (center of the gauge) due to a malfunctioning thermostat, the heater control valve is not letting hot coolant into the heater core, there is a restriction in the heater system that is preventing adequate hot coolant flow through the heater core, the heater fan is not working to transfer heat from the heater core to warm air for the passenger compartment, or the air blend doors inside the heater are not working properly to route warm air to the desired vents. I would recommend a heater system inspection](https://www.yourmechanic.com/services/heater-is-not-working-inspection) by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

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