[Bally12345]

Got no heating in my w203 A/C cold works but no hot air until engine warms up and even then its not a lot. The fans blow but just cold air. Is this just a blown fuses or bigger problem?

Got a fuse pack in the boot. UK model

 

[rudeney]

First, do the test/reset procedure on the climate control system:

With the engine running, press and hold the RECIRC and FRONT DEFOG buttons simultaneously for several seconds until their indicator lights begin to blink. The system will run a test of the ductwork dampers and servos. If all is successful, the light will stop blinking after 20-30 seconds. If not, then you have a damper/servo problem and you should get a full diagnostic run to determine the exact problem.

If the problem isn't in the ductwork, then it might be a defective engine coolant thermostat or the valves controlling coolant flow through the heater core.

 

[Bally12345]

First, do the test/reset procedure on the climate control system:

With the engine running, press and hold the RECIRC and FRONT DEFOG buttons simultaneously for several seconds until their indicator lights begin to blink. The system will run a test of the ductwork dampers and servos. If all is successful, the light will stop blinking after 20-30 seconds. If not, then you have a damper/servo problem and you should get a full diagnostic run to determine the exact problem.

If the problem isn't in the ductwork, then it might be a defective engine coolant thermostat or the valves controlling coolant flow through the heater core.

Thanks tried this and the lights didnt stop after 30secs or even after 3minutes so guess need to get a full diagnostic done.

 

[rudeney]

Yep - it's probably a broken actuator for the mixer flap - that seems to be common. But again, I'd pull codes before digging into it because working under the dash is a real pain so you'll want to know exactly what you need to repair. Oh, and generic OBDII code readers won't do this - you need MBZ Star Diagnosis which of course the dealer has, and some indy shops. You can also buy the Chinese clone version on eBay for about $500.

 

[Bally12345]

Yep - it's probably a broken actuator for the mixer flap - that seems to be common. But again, I'd pull codes before digging into it because working under the dash is a real pain so you'll want to know exactly what you need to repair. Oh, and generic OBDII code readers won't do this - you need MBZ Star Diagnosis which of course the dealer has, and some indy shops. You can also buy the Chinese clone version on eBay for about $500.

Guess what the heating is working again! :thumbsup: It must have reset or dislodged something I dont know but its working after your instructions now to fix all the other stupid problems! :surrender: