Why am I getting a stale smell from ac - 530d BMW Cars & Trucks

no info generic answer clean-flush- /replace fuel system ---tune up --

very difficult to do so
look at why there is an odor to start with
smoking with the ac on, empty tins and food scraps
water under carpets, dirty ac evaporator fins full of greasy gunk
rotten leaves and such in the outside vent from where the air comes into the car
all of these contribute to the smell
one idea suggested on face book is to get an empty glass bottle with a tin lid--punch holes in the lid , fill the bottle with a low temp melting aeromatic candle and place that in the door trim or console
That way when the cabin heats up the candle melts enough to let of the aroma that will combat the smells

antifreeze anywhere inside the cabin is a sign of a leaking heater core. Rub the liquid between two fingers. If it feels oily, it's coolant.

The condensation is not completely draining. You may want to see if it is plugged. Find the drain area in the engine compartment on the bottom of the firewall. Use an air compressor to blow air back through to clear it. I had a problem with that area which was a ford expedition design flaw. It was draining onto my O2 Sensor and damaging it. I had to make a bypass with a part form a GM truck.

Check that oil isn't dripping on the exhaust manifold. This will make a horrible smell. If it isn't then replace the pollen filter in the air system and check the water in the header tank is clean. Coolant system water can smell very stale if it isn't changed during servicing. To do this simply undo the bottom hose on the radiator. When empty refill and leave the engine running with the coolant top off. This will bleed the air system, you will notice the water level will drop when the thermostat is open so make sure you top up when this happens. When all air bubbles are clear screw the cap back on.

You may also want to change the gas in the air conditioner. Take it to an approved garage to do this as they usual guarantee a 15 degree drop in temperature after a change

Hope this helps

HAVE THE STARTER FOR CLUTCH CHECKED,IT MAY BE BRAKING DOWN.

Spray Lysol, entire can, into air intake at base of windhield. Fan on low speed. You are smelling mold & mildew. Lysol will kill it. May take a few applcaitions.

If you run your Air cond on recirculate always try using an air sanitizer in your return vent. Or switch your A/C to outside air flow for for half an hour and raise the rear of your sunroof panel to vent the stale air do this till the smell dissipates and then close he sunroof and reset the A/C to recirculate if desired.

Blower motor is easy. Under glove box, three or four bolts.

If the drain hole for the A/C condensation gets plugged, it build up and smell stale due to rotten debris. This could also hurt your A/C evaporator core and make eventually even make it leak.

If the water builds up, then it could get in your blower motor as well and cause problems there.

Take the blower motor out and test it by hooking leads from it to your battery. Have a firm grip on it b/c it'll be a squirrel cage blower and it'll want to twist out of your hands if it decides to work.

Take some dye and inject it into your A/C system to trace the leak. I found dye leaking into my floorboard which told me the drain hole was not only plugged but also that the evap core was leaking.

that job I haven't done yet. the smell you are getting is it a real sweet smell? If it is possible antifreeze leak. Beyond that I;m not really sure. Unless someone poured something down into the cowl vent. Do you get the smell when the ac is on with vents open or recirculator button pushed?