Running air con with the windows open

[Actin]

Is a big no-no due to it messing up the air con thermostat isn't it? I've accidently opened the window once or twice.

How long does it take before damage is done? Also what temp should the air be at when its set to the coldest setting with the a/c running?

[andyman7931]

never ever heard this. If you run with the AC on you're just wasting energy...

[tastade]

I do it sometimes because I like my windows down, but I don't want to cook either. I have never had it hurt anything, my AC is as cold as ever. I usually just do this for a few minutes until the car cools off a bit and then I turn off the AC or roll up the windows. What I do more often though is run the heater in the winter with the windows down.

[Tyler]

Nothing will happen by doing this.

[campaiar]

A vehicle air conditioner ideally should output around 35-36 degrees at the vents with re-circ on.

Given that your car is 7-11 years old, its probably lost a step.

[bmw318tiChic]

I've never heard of any problems with driving with the AC on and windows open... I'm the same as "tastade".... so often I'll just ride with the windows down and heater on in the winter!

[DustenT]

Is a big no-no due to it messing up the air con thermostat isn't it? I've accidently opened the window once or twice.

How long does it take before damage is done? Also what temp should the air be at when its set to the coldest setting with the a/c running?

It doesn't matter. The AC is a sealed unit, air is simply blown over the exchanger to make cold air. Now if your interior was filled with compressed freon.....that would be a problem.

[andyman7931]

It doesn't matter. The AC is a sealed unit, air is simply blown over the exchanger to make cold air. Now if your interior was filled with compressed freon.....that would be a problem.

if that's the case, you'd have bigger problems than your ac not working well! :eek:

[Tyler]

A vehicle air conditioner ideally should output around 35-36 degrees at the vents with re-circ on.

Given that your car is 7-11 years old, its probably lost a step.

Actually the air coming out of the vent should be inbetween 65-68 degrees,thats with the heat control turned all the way counter clockwise.. If your a/c is putting air out at 35-36 degrees your cars a/c has serious problems. Thats 5 degrees above freezing. Even new cars don't go that low. You want to use the re circ once the temp in the car is cool then it will just re circ the air inside. My car still puts out about 66 degrees.

[Severian]

Nothing will happen by doing this.
Actually, not true for some cars. Apparently not ours, but for my '99 mazda protege ES...

Campaign Number: 00V301000 Date: 2000-Oct-05
Component: Equipment: Electrical: Radio/tape Deck/cd Etc.

Defect Summary: VEHICLE DESCRIPTION: PASSENGER VEHICLES EQUIPPED WITH A PARTICULAR FACTORY INSTALLED AUDIO UNIT. IF THE VEHICLE IS OPERATED AT LOW SPEED IN A HOT AND HUMID ENVIRONMENT WITH THE WINDOW OPEN, AIR CONDITIONER RUNNING, AND AUDIO ON, CONDENSED WATER ON THE A/C DUCT SURFACE COULD DROP AND ENTER INTO THE AUDIO UNIT, CAUSING A SHORT CIRCUIT.

Consequence Summary: IF THE SHORT CIRCUIT OCCURS AT ONE SPECIFIC SET OF TERMINALS, THE REAR RIGHT LOUDSPEAKER CAN OVERHEAT AND, IN SOME CASES, CATCH FIRE.

[andyman7931]

but that's not damage to the AC unit... that's a poorly designed condensation system causing damage to something else...

[mrnine]

Wow...way to go Mazda. I can't imagine that BMW would build a car that if you accidentally ran your ac and your stereo with your windows down, your rear speaker could catch on fire. I can't help but giggle as I type it just thinking about it. That's perhaps the most ridiculous design flaw I've ever heard of.

[Actin]

^^^ sure is a crazy design flaw lol.

Anyway great info as always folks thanks!

[tastade]

Actually the air coming out of the vent should be inbetween 65-68 degrees,thats with the heat control turned all the way counter clockwise.. If your a/c is putting air out at 35-36 degrees your cars a/c has serious problems. Thats 5 degrees above freezing. Even new cars don't go that low. You want to use the re circ once the temp in the car is cool then it will just re circ the air inside. My car still puts out about 66 degrees.

Note that condensors in AC units do ice over on occassion (usually from a problem). It wouldn't surprise me if the air could get down to 35 degrees, I know my hands go numb if I point the vent at my hand on the steering wheel. Now I am going to have to go home and measure my as temp after work. But I am guessing mine get down around 40 or 50 F.

I had an old 300zx where the condensor would ice over after an hour of operation and the AC would stop working. I would turn it off for 10 minutes and it would be good for another hour. This only happened in very hot and humid climates.

This is also what causes that pool of water under your car when you stop after your AC has been running (condensation running off). I hate it when I am at a gas station and someone goes "look, your car is leaking fuel!" Then I have to explain to them that it is condensation from the AC. At least they are trying to be helpful.

[Severian]

but that's not damage to the AC unit... that's a poorly designed condensation system causing damage to something else...
You seem to have missed the point of the humor in my post. However I should have been more clear that I was not being argumentative.
:smile:

[Tyler]

Note that condensors in AC units do ice over on occassion (usually from a problem). It wouldn't surprise me if the air could get down to 35 degrees, I know my hands go numb if I point the vent at my hand on the steering wheel. Now I am going to have to go home and measure my as temp after work. But I am guessing mine get down around 40 or 50 F.

I had an old 300zx where the condensor would ice over after an hour of operation and the AC would stop working. I would turn it off for 10 minutes and it would be good for another hour. This only happened in very hot and humid climates.

This is also what causes that pool of water under your car when you stop after your AC has been running (condensation running off). I hate it when I am at a gas station and someone goes "look, your car is leaking fuel!" Then I have to explain to them that it is condensation from the AC. At least they are trying to be helpful.


I will bet $500 if you call any car dealership and ask them how cold the air is supposed to come out of the vents when the a/c is on and they'll say inbetween 65-70 degrees. A friend of mine owns a 2005 Mercedes CLK 320 and it has the digital readout for the temp gauges,it doesn't go below 66 degrees,same on a Lexus. I check mine out every year with a thermostat and it's about 67 degrees. I've been around cars shops since i was born and believe me it shouldn't be that cold & if it is the a/c has problems. If i stick my hand in front of my a/c in my room my hand get numb and that goes down to 66 degrees.

[318tiRedLeather]

My dad has a 2000 323i and the climate control goes all the way down to 59 degrees

[red87m6]

Hello everyone, the temperature of the air out my vents is 48 to 51 degrees cycling. Air condition systems have thermostatic switches with capillary tubes stuck in the evaporator coil to prevent icing above the first third of its height. I live in Las Vegas Nv. and any of my vehicles ( 93 740i, 87 m6, 02 silverado will blow at least 47 degrees at 105 degrees outside ambient temp.

The system is design to function and compensate for humidity, elevation and engine speed with control devices like expansion valves or orifice tube, thermostatic switch, manditory pressure switch and relief valves.

Clean your radiator and condenser coil for better heat transfer and you can see 5 degrees cooler air.

Thanks for my first post, I repair heavy equipment here and this is one of the most important repairs now.
red87m6

[mohaughn]

I'm with red on this one. I had my AC serviced last year and it was blowing 45 degrees inside the vent after they were done. They stuck the thermometer into the vent before they did the work, and after to show me that they fixed my issue...

I have a 97 328i with the electronic temp control, as well as a 525iT with the electronic controls. Both of them go down to 60 degrees. However, that is the ambient temperature when the system turns itself off, not the temperature of the air coming out of the system.

For instance, if I have my car(328 or 525) set at 77, which is where it usually is, when I first get into the car it will run full blast for about 5 minutes, then it will run at about half power for 5-10 minutes, and then it fluctuates between low power and half power to keep the temperature at 77 degrees. In both of those cars if you turn the automatic controls down to 60 they just run full power all of the time in the Florida heat. I must say though that the automatic controls on the e49 are much better than those on the e36. Even though the system works the same, the e49 seems to regulate the temperature much better.

[m3outtanowhere]

Actually, not true for some cars. Apparently not ours, but for my '99 mazda protege ES...
comon thats a specific incidence withan obvious design flaw.

[pdxmotorhead]

R12 systems get about 10 degrees colder than R134. Just a side note...

AC systems have a specific capacity for cooling based on coil size fan speed and inlet air temperature. Its usually a capacity of about 40 degrees below outside ambiant. Any R12 or R134 is capable of cooling down to below zero but most have a limit switch to limit freezing. R134 systems are prone to Overpressure if run too hard so they are usually limited to between 40 and 45 degrees F because of this.

Dave