Q: My 2008 Mercedes-Benz heater blows warm then cool air

asked by on

The heater blows warm air not hot and then it will blow cool air and then it will repeat the coolant is good I had a service three months ago could it be the thermostat or do I need to do something else
My car has an automatic transmission.

The lack of heat being generated by your system may indicate a clogged heater core. The [heater core]((https://www.yourmechanic.com/services/heater-is-not-working-inspection) is a small radiator like unit that circulates the hot coolant from the engine through the heater core which then uses this warm coolant to heat the inside of the car with the help of the blower motor that blows the warm air through the vents inside the car. The other possibility is that the thermostat may not be allowing the engine to reach a normal operating temperature and since the engine’s warm coolant is the essential source of the heater core supplying heat to the inside of the vehicle, this can impact the warmth of the heat inside the vehicle. I would suggest having an expert from YourMechanic come to your location to diagnose your heating system.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. My 2008 Mercedes-Benz heater blows warm then cool air

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: 2005 Ford Five Hundred transmission filter removal

I'm going to assume you have the CFT30 continuously variable transmission (CVT). There are two filters on this transmission: a traditional internal filter and an external 'High Pressure' filter. To remove the internal filter, first remove the transmission pan. Then,...

Q: The Esl is locked car won't start

With ignition on look to see if theft light is on or blinking to see if theft system is active. Sometimes another key if you have one will start vehicle if the key FOB is defective.If the battery is dead...

Q: Intake manifold stuck open

I'm guessing that you mean your throttle body is stuck open? These vehicles are known for having problems with their throttle bodies. I would ask for help from one of the mechanics at YourMechanic to come and examine your vehicle...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.