[gomichaelkgo]

     Featured on BIMMERPOST.com

Mold forms on the evaporator because it gets wet. If you can dry it off before your car is stored for the next drive, it won't get so moldy.

1. Store the "Climate Settings" feature to a preset.
2. When you reach your destination, press the preset and then i-drive down button to activate parked car ventilation (preferably with the windows or sunroof open as much as practical)
3. Lock the car and be on your way as the blower dries off your evaporator.
4. Wipe hands on pants.

[DarkTrigger]

Originally Posted by gomichaelkgo

Mold forms on the evaporator because it gets wet. If you can dry it off before your car is stored for the next drive, it won't get so moldy.

1. Store the "Climate Settings" feature to a preset.
2. When you reach your destination, press the preset and then i-drive down button to activate parked car ventilation (preferably with the windows or sunroof open as much as practical)
3. Lock the car and be on your way as the blower dries off your evaporator.
4. Wipe hands on pants.

I get step 1-3, but I'm curious as the point of step 4?

[ft1338]

Someone said before that the A/C button should always be on even when blowing warm air, in order to prevent mold build up. I'm just wondering what A/C does when you're blowing hot air? I thought A/C was for cold air only?

[giddyup69]

Originally Posted by ft1338

Someone said before that the A/C button should always be on even when blowing warm air, in order to prevent mold build up. I'm just wondering what A/C does when you're blowing hot air? I thought A/C was for cold air only?

it helps remove humidity from the air

[Poohbore]

I never turn a/c off. Dehumidifies the air coming into the car and keeps the car windows clear when it's raining

[OC40]

Originally Posted by Poohbore

I never turn a/c off. Dehumidifies the air coming into the car and keeps the car windows clear when it's raining

Rain? What's that?

I turn mine off for most of the "winter" unless I parked outside for a few hours.

[ft1338]

Originally Posted by giddyup69

it helps remove humidity from the air

But how? What is the mechanism? Is the A/C button circulating the freon gas which in turns removes the humidity thanks to condensation? Isn't it counterproductive to push hot air through cold freon tube in the winter? Seems like the heater has to work harder if air has to go through a cold freon tube before entering the cabin. Sorry if it's obvious to everyone but I can't make sense of the combination of heated air and A/C AT THE SAME TIME in the winter.

[Poohbore]

Originally Posted by OC40

Rain? What's that?

I turn mine off for most of the "winter" unless I parked outside for a few hours.

Come over to Blighty and you'll see plenty of it !

[Steve33]

Having the AC on 1) dehumidifies the air and 2) makes the compressor run. Think of it like a house, you have the compressor outside that puts out the heat and sends the cold gas inside to your exchanger/furnace.

Your refrigeration coils cause the humidity in the air to form ice around them so when you turn your car off and the ice starts to melt, you have stagnant water in your AC which causes the stench.

Also, that's why when you race you should run your heater... it'll help to lower the water temp because it uses that to generate heat. It acts as a mini radiator. Having the AC on reduces gas mileage and power

[BavarianFanatic]

Originally Posted by ft1338

But how? What is the mechanism? Is the A/C button circulating the freon gas which in turns removes the humidity thanks to condensation? Isn't it counterproductive to push hot air through cold freon tube in the winter? Seems like the heater has to work harder if air has to go through a cold freon tube before entering the cabin. Sorry if it's obvious to everyone but I can't make sense of the combination of heated air and A/C AT THE SAME TIME in the winter.

Psychrometrics. In short, the air blowing through the evaporator is cooled below its dewpoint temperature which causes the excess moisture in the air to condense and drain away. The air leaving the evaporator is very cold and now saturated (100% RH) so the process of reheating it lowers the overall relative humidity.

As far as the original intent of this thread - you shouldn't get a musty smell unless your drains are clogged. In fact, the concept of blowing air through an idle coil will actually pick up all of the moisture that was on the evaporator and carry it throughout your whole A/C system. This "carryover" is far more likely to create musty nastiness than leaving it all at the coil.

[BavarianFanatic]

Originally Posted by Steve33

Having the AC on 1) dehumidifies the air and 2) makes the compressor run. Think of it like a house, you have the compressor outside that puts out the heat and sends the cold gas inside to your exchanger/furnace.

Your refrigeration coils cause the humidity in the air to form ice around them so when you turn your car off and the ice starts to melt, you have stagnant water in your AC which causes the stench.

Also, that's why when you race you should run your heater... it'll help to lower the water temp because it uses that to generate heat. It acts as a mini radiator. Having the AC on reduces gas mileage and power

This is only partially correct. For starters, liquid refrigerant enters the evaporator. It then "evaporates" as it absorbs the heat from the air blowing through it. This hot gas is then pumped back through the compressor to the condenser where the hot gas "condenses" back to a liquid as it rejects the heat it picked up at the evaporator. Lather, rinse, repeat.

You shouldn't have ice building up on your evaporator. Just liquid water. If there is ice, you either have a low refrigerant charge or restricted airflow. If it's icing up, it'll eventually block all air flow.

Again, you shouldn't get mold/mildew growth unless your drain is clogged. This is a small maintenance item that is often overlooked.

[F104]

Originally Posted by BavarianFanatic

. This is a small maintenance item that is often overlooked.

hmm..Yes small in size, but a pain to get too, and difficult to determine if it does drain. Any recommendations are welcome, so far my test has been to poor water into the inlet under the cabin air filter, and see if it drains on both sides of the transmission with bottom panel removed. I can think of easier jobs

[BavarianFanatic]

Originally Posted by F104

hmm..Yes small in size, but a pain to get too, and difficult to determine if it does drain. Any recommendations are welcome, so far my test has been to poor water into the inlet under the cabin air filter, and see if it drains on both sides of the transmission with bottom panel removed. I can think of easier jobs

Just check to make sure you see condensate dripping when you have the A/C running. If not, just run a wire up in the drain tubes. Hardest part is getting under the car.