i have 06 dodge 2500 with heater treater doors installed in dash. i recently developed a noise on the passenger side that sounds like fresh air is coming in the cab. the weird thing is when i turn the HVAC fan on any setting that noise goes away. its like the fresh air is coming in when the fan is off but as soon as i turn the fan on it doesnt allow the fresh air in. anyone have any ideas? and i put the heater treater doors in last fall and i just started hearing the noise 2 weeks ago-thanks

 

check the fresh air vent door,mine servo broke off the tab and mine did the same thing,except i had the plastic piece jumpijng around in the squirrel cage when i turned on the fan.

 

Can I access that by pulling the fan off and access it through there or do I have to take my dash apart