Mike Murphy

I believe the car will not allow the AC compressor to run if the outside temps are low enough to cause any damage to the system, which means it’s safe to use it all the time.

Agree, even in the winter, if it’s cold and rainy, using AC reduces humidity in the cabin and can help prevent mold.

On the 996 model, using the AC button, regardless of if the compressor is engaged, engages the front two cooling fans on low speed for the radiators, which keeps engine temps a bit lower, even in the winter, during vehicles speeds that are low (such as heavy traffic).

MrMoose

Yeah, but be aware it can grow mold in the AC system. All that humidity you're pulling out of the air condenses on the evaporator and drains into the heater box (that's the drip you get out the heater box drain hose when running the A/C). The issue is that if you leave the A/C on all the time that moisture just sits on the coils when you turn off the car and grows stuff, and you can wind up with a musty-smelling A/C system. A good practice on any car is to turn the A/C off about 2-3 minutes before you shut off the car but keep the blower on high. This helps dry off the evaporator coils and can prevent mold growth and that musty smell.

I've also had good luck using BG Frigi-Fresh every couple of years when I replace the cabin filter on the Cayman, or when I notice any odor. I've tried a few products and this has worked best.

https://www.bgprod.com/catalog/clima...g-frigi-fresh/

Mike Murphy

I’m glad you mentioned this, as this happens all the time in our 2019 BMW X3.

MrMoose

Yeah, it happens on a lot of cars. The 987/997 seem particularly prone to it, though.

If you use the BG stuff to kill what's growing in there, make sure you've got the dust/pollen filter in place, and then make some effort to dry out the evaporator before parking it helps. I can typically go a couple years before I start smelling it again when the AC comes on, then it's time for another spray down.

Astur

Living in the Caribbean with it's high temperatures and humidity year round my A/C is ALWAYS on.

My '09 997.2 C2 with its current 31K miles and which I've owned for over 7 years, surprisingly enough cools quite well. To its credit I've never had the system serviced nor recharged with gas which in itself is quite an statement.

Mike Murphy

So on my 996, turning off the AC and using high speed blower to dry the condenser out only take a min or two. However, my 2019 BMW X3 has a heat pump, and the separate heat exchanger and coolant (there are two coolant reservoir tanks on this car) means that there is a good deal of residual cool fluid in the system, even after the compressor is turned off. So it takes a lot longer to dry out the system. Maybe if I drove faster/harder, that would help, lol, as this 2nd cooling system is also used to cool the intercooler!

Qwksnke

What is this ECO mode you mentioned? I have not seen this anywhere in my 09 S settings?Not that I would use an ECO mode but I am curious