Open vent or closed vent

Air Conditioner Unit: Vent Open or Closed??
Air Conditioner Unit Vent Open or Closed

Some cars use vacuum from the engine to open and close the doors that direct the air to different positions. It is possible that the vacuum line to the controls is cracked or disconnected.

OPEN THE VENT

Are all the vents working? Does your Cruise Control work (properly) it may work and shut off. If your vents are working is only hot air or cold air coming thru, or just your defroster vent?

You have a 3 way check valve under fuel rail guard on passengers side, its a pastic barrel shape thing it rots and creates holes in it causing your ac vents and cruise control to malfunction.

next your heater control unit if you have the one with a slider to regulate the hot or cold temperature breaks easily inside unit, its only plastic. Its an arm inside unit to control the temp in car it slides a door open or closed for heat. If you look where he slider enters thru that hole space you will see a post it sits on to open and close .

BEST TO LET BMW DEALERSHIP REPLACE HEATER BLOWER IF NOT MISTAKEN YOU HAVE TO DISCHARGE AC SYSTEM TO REMOVE REFRIGERANT LINES TO REMOVE BLOWER MOTOR COVER.THIS IS NOT HOME FIX.BMW CARS NOT EASY TO WORK ON.YOU HAVE TO BE BMW MECHANIC TO WORK ON THEM.

Sounds like a bad actuator on the dampner. Look for things connected to the ducting, see if you can manually open and close the dampner.

It's most likely an airflow problem, you say you had the vents closed? Icing up is normally caused by lack of load (air flow) or loss of refrigerant charge. Make sure all your vents are open to allow for as much airflow as possible and that your filter is clean. Some units do not work well on low airflow setting when the outdoor temps cool down at night.

The AC/Heater unit has electric motors the open and close all the vents and heat to cold doors. when these electric motors begin to open or close past their stop points, the motor try to continue to open and close itself properly, thus fourth its tapping all the time. to see which one it is, turn the heater control to cold and slowly to hot. most of the time, its the heater door. if not, do the same with the vent control. the problem is common withe the GM SUV's.

Try and check all of your flapper doors and make sure they all have vacuum lines connected to them. These vacuum lines control different flapper doors depending on what setting your A/C and heating system are set at. For instance defrost opens the top flapper doors in your dash, bi-level opens the lower flappers and mid-dash flappers. What I would recommend is first checking each setting. Turn the car on and first run defrost. If both flappers are open then those are ok. Then run regular A/C, make sure the flapper doors are open to all the mid-level vents, if that is ok move on to the lower level setting and check that. This will help you pinpoint what doors are having issues. When you find the one that is not opening or not closing this will be the door and that is the one that does not have the vacuum hose connected. Let me know how everything goes.

Keep me posted - Tech101

F1, F2, and F3 are the strength of the fan blowing the air conditioner. F1 circulates the least amount of air, F3 the most. I generally find that if the air conditioner isn't getting the job done on F1, F2 will do it. I typically only use F3 if I just want to circulate air fast in my place for awhile. As far as what is "better" with closed vent or open, that depends on what you want to do. If you are using air conditioning on a hot day, then vent closed is better because it will cool only air circulating in your place. Vent open will allow fresh air in from outside, and if it's a really hot day, the air conditioner might have a harder time cooling off the fresh air than the circulating air inside your place (as it's continually being cooled repeatedly by your air conditioner).