# How cold is your A/C?



## Magna (Jan 4, 2002)

When I got my '04 I was thrilled that the A/C blew colder than my '00 (although the '00 A/C was still pretty good). Anyway, I had to bring my '04 in because the idle valve got stuck open and since my car was in I asked the dealer to look at the A/C because it was a bit smelly. They treated the filter with Wurth A/C treatment. When I got my car back the A/C didn't work as well--the air wasn't cold enough. Finally, I brought it back to the dealer and they re-charged the A/C and they added .2 pounds of freon, it's better but it still doesn't blow as cold as when I first got the car (car is 3 months old)?!?!? Any ideas why? I set the temp to 65 and it's still not as cold as when I set the temp to 68 in my old '00 car. I wonder if the problem is not with the freon but the temp sensor? Or is there another setting to the A/C that only the Techs have access to, to make the A/C colder? Any insight would be appreciated.


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## tgravo2 (Dec 7, 2002)

Magna said:


> When I got my '04 I was thrilled that the A/C blew colder than my '00 (although the '00 A/C was still pretty good). Anyway, I had to bring my '04 in because the idle valve got stuck open and since my car was in I asked the dealer to look at the A/C because it was a bit smelly. They treated the filter with Wurth A/C treatment. When I got my car back the A/C didn't work as well--the air wasn't cold enough. Finally, I brought it back to the dealer and they re-charged the A/C and they added .2 pounds of freon, it's better but it still doesn't blow as cold as when I first got the car (car is 3 months old)?!?!? Any ideas why? I set the temp to 65 and it's still not as cold as when I set the temp to 68 in my old '00 car. I wonder if the problem is not with the freon but the temp sensor? Or is there another setting to the A/C that only the Techs have access to, to make the A/C colder? Any insight would be appreciated.


in my 2002 325, my A/C takes a few minutes before it starts blowing cold. Then it's not even that cold. After a little while though it cools the car off enough and stays cool. I'm usually thinking more about how great the other aspects of the car are.


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## bmw330zhpfan (May 1, 2004)

When you set the thermostat to a lower setting, the AC does not "blow colder". It blows at one temperature only. It will adjust fan speed to attain the setting as required. 

For example, if the cabin temperature is 70 F and you set the temperature to 68 F the fan will throttle back as 68 F is only 2 degrees from the cabin temperature. Reduce the temperature to 64 F and the fan will throttle up as the system "dumps" cool air into the cabin to reduce the cabin temperature accordingly. As the cabin temperature decreases, you will notice the fan speed throttle back accordingly. 

It's a function of heat transfer. Think of it as a bucket with a hole in it. You want to fill the bucket to a certain height so you poor water in, but because of the hole you need to keep pouring the water in at a certain rate. If you want the height of the fluid in the bucket to be higher, you will need to pour water into the bucket at a faster rate. When you think of this as your interior, consider the water entering the bucket as the air conditioning entering from the ventilation and the hole as the losses due to outside temperature, sun load, etc... 

Now enough of that [email protected], most OEMs have a target air temperature at a known condition. Typically it is lowest temperature setting, at idle (vehicle not moving), recirculated air (max AC). After the system stabilizes, you want approx. 40 F from the ventilation system (measured @ the vent itself). You can pick up a refrigeration thermometer pretty cheap at a plumbing supply shop to verify this. With the introduciton of the CFC free refrigerants, the 40 F target has proven elusive. I know this because I converted a R12 system to R134a and noticed a performance difference immediately. I used to get condensation from the ventilation (it was painfully cold). After the conversion, it was typical of today's performance. The only way I could get 40 F was to drive the car (cooling air passing over the condenser). Was your older vehicle an R12 system? That could explain your performance difference. 

Perhaps someone has a Bentley manual and can advise on the "target" temperature range for a 3 series AC system (as well as the test condition). I do not know the 3-series AC system in detail, but I suspect the expansion valve (that flashes the liquid to vapor) is a fixed orifice device and as such no adjustments are possible, but variable orifice systems are in production, however they are not adjustable. 

Since you've gotten your car back, has the outside temperature increased? Outside load on the condenser will affect refrigerant performance thereby affecting AC performance.


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## AB (Jan 11, 2002)

My 996 blows the coldest A/C out of any car I have ever owned. The 330i was good, previous Mustangs were just OK, 4Runner was pretty good, but nothing like the Porsche.


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## bmw330zhpfan (May 1, 2004)

Ryan330i said:


> My 996 blows the coldest A/C out of any car I have ever owned. The 330i was good, previous Mustangs were just OK, 4Runner was pretty good, but nothing like the Porsche.


The R12 system I mentioned above was in a VW GTI. Wicked cold. Must be a Porsche/VW/Audi thing.


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## Technic (Jun 24, 2002)

Magna said:


> When I got my '04 I was thrilled that the A/C blew colder than my '00 (although the '00 A/C was still pretty good). Anyway, I had to bring my '04 in because the idle valve got stuck open and since my car was in I asked the dealer to look at the A/C because it was a bit smelly. They treated the filter with Wurth A/C treatment. When I got my car back the A/C didn't work as well--the air wasn't cold enough. Finally, I brought it back to the dealer and they re-charged the A/C and they added .2 pounds of freon, it's better but it still doesn't blow as cold as when I first got the car (car is 3 months old)?!?!? Any ideas why? I set the temp to 65 and it's still not as cold as when I set the temp to 68 in my old '00 car. I wonder if the problem is not with the freon but the temp sensor? *Or is there another setting to the A/C that only the Techs have access to, to make the A/C colder?*Any insight would be appreciated.


There is a programmable HOT COUNTRY setting in the Car and Key memory feature. I have it programmed in my car because I live in Florida. Normally my A/C temp setting was 62 degrees, after the programming I set my temp to 72 degrees. It does make a significant difference in the cold temp and the speed of cooling.

However, according to the description of your problem this feature will only cover up a bigger problem IMO. It seems to me that you have some leak in the A/C lines or the compresor/condenser is malfunctioning. It is a '04 vehicle, thus having a smelly A/C this soon in a new car is not a normal thing. My advice is to take the car to an independent A/C specialist for a complete check up, record whatever they find and take it back to the dealer.


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## AB (Jan 11, 2002)

bmw330zhpfan said:


> The R12 system I mentioned above was in a VW GTI. Wicked cold. Must be a Porsche/VW/Audi thing.


I believe this to be the case. I have a nephew who had an older Jetta and he said the A/C on that thing was BY FAR the most ice-cold A/C he has ever experienced.


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## Scott ZHP (Jul 17, 2003)

bmw330zhpfan said:


> When you set the thermostat to a lower setting, the AC does not "blow colder". It blows at one temperature only. It will adjust fan speed to attain the setting as required.


I'm not 100% positive, but I don't think this is entirely accurate. I have always been under the impression that BMW mixes warm air to the constant cold to in order to vary the temperature (similar to what the blue/red dial on the center dash vent does).


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## Kaz (Dec 21, 2001)

The other thing that BMW IHKA does is monitor outside temp (behind the bumper), inside temp (through the little grille on the front of the control panel) and some sort of 'solar level' (sensor on top of the dash). So depending on what readings it gets from those three, it'll determine how to run the fan, position the vents, and mix air. And there is that Hot Country setting that Technic mentioned, though I don't know what that's set to by default in the US.

Once it gets going, the (presumably) R12 system in my 6er blows WAY cold.


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## NP2004 (Feb 5, 2004)

The AC isnt nearly as cold as my lexus and takes a bit longer to get cold but 95% off the time I have all the windows and sunroof down so I can hear the BMW exhaust and engine! :thumbup:


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## bmw330zhpfan (May 1, 2004)

Scott ZHP said:


> I'm not 100% positive, but I don't think this is entirely accurate. I have always been under the impression that BMW mixes warm air to the constant cold to in order to vary the temperature (similar to what the blue/red dial on the center dash vent does).


It could be the case, as I said I am not entirely familiar with the intricaces of the 3-series system. In fairness I did speak of a "typical" system. If it blends air as you indicate, it will clearly blow air at different temperatures.


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## PABS (Apr 3, 2003)

According to my independent mechanic....when setting the AC to the lowest temp the measurement at the vents should be abiut 38 degress F.

I have verified this on both my 2001 E46 and my 1995 E34. Keep in mind that the AC will always blow colder when the revs are higher since this causes the compressor to work better.

So always test the AC while revving the engine.


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## KP (Apr 16, 2002)

Wish mine would create condensation like the x3 loaner I had...that thing was COLD :thumbup:


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## Magna (Jan 4, 2002)

bmw330zhpfan said:


> When you set the thermostat to a lower setting, the AC does not "blow colder". It blows at one temperature only. It will adjust fan speed to attain the setting as required.
> 
> For example, if the cabin temperature is 70 F and you set the temperature to 68 F the fan will throttle back as 68 F is only 2 degrees from the cabin temperature. Reduce the temperature to 64 F and the fan will throttle up as the system "dumps" cool air into the cabin to reduce the cabin temperature accordingly. As the cabin temperature decreases, you will notice the fan speed throttle back accordingly.
> 
> ...


I am pretty sure my old car had R134a. The AC was great until I brought the car in to have the mouldy smell checked out. Perhaps in checking the AC some freon got let loose. Hopefully, with the AC recharged with an additional .2 pounds of freon things will go back to as before. *Is .2 pounds of freon significant?*

*I brought my car in to have the speed idle valve replaced because it was stuck open. Hopefully, the tech didn't cause a hole in the AC system from replacing the valve.*


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## Magna (Jan 4, 2002)

Technic said:


> There is a programmable HOT COUNTRY setting in the Car and Key memory feature. I have it programmed in my car because I live in Florida. Normally my A/C temp setting was 62 degrees, after the programming I set my temp to 72 degrees. It does make a significant difference in the cold temp and the speed of cooling.
> 
> However, according to the description of your problem this feature will only cover up a bigger problem IMO. It seems to me that you have some leak in the A/C lines or the compresor/condenser is malfunctioning. It is a '04 vehicle, thus having a smelly A/C this soon in a new car is not a normal thing. My advice is to take the car to an independent A/C specialist for a complete check up, record whatever they find and take it back to the dealer.


Yeah, I have my car set to HOT COUNTRY when I took delivery. My old '00 never smelled. Trapped water/moisture causes the mouldy smell, right? The techs supposeldy tested my AC for leaks, would this also test if the compressor is working correctly?


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## Magna (Jan 4, 2002)

PABS said:


> According to my independent mechanic....when setting the AC to the lowest temp the measurement at the vents should be abiut 38 degress F.
> 
> I have verified this on both my 2001 E46 and my 1995 E34. Keep in mind that the AC will always blow colder when the revs are higher since this causes the compressor to work better.
> 
> So always test the AC while revving the engine.


Hi PABS, is that 38 when the car is moving? After recharging the tech said he could only get it to 41 F in the vent. Before re-charging it was 46 F.


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## PABS (Apr 3, 2003)

38F with the engine revving...not the car moving


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## 330soon2b (May 30, 2004)

My car is very cold at 70. Just got rid of an 04TL and it was not nearly as cold. The Accord I owned before the TL worked well. I am happy with the ac in the 330.


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## RKT BMR (Sep 7, 2002)

Always keep in mind, gang, on matters like this terms like, "cold", "cool", "warm", "hot" are so subjective as to be virtually meaningless in judging other people's opinions.

You could ask my wife and I sitting in the same car cabin at the same temperature whether it was "cold" or "warm", and if she says, "cold" there's a damn good chance I'm gonna say "comfortable" or even "warm".

Thank God for zoned climate controls in our Town&Country. While imperfect, it is still a vast improvement over the tug-o-war we used to have with the Grand Cherokee's climate system on family outings.  

So, that said, anyone here that states the 3-series AC is pathetically wimpy all the way across the range to those that opine that it is like being in the Arctic are not really saying anything you can draw much meaning from. You've simply got to try it out for yourself.

So, what to do? If you're researching to buy, go to the dealer on a relatively hot day, and make sure they will let you sit in the car with it running for ten minutes or so before the test drive to get an idea of the idling performance of the system, and its ability to equalize temps when first started up. Then, take it on a 15 minute test drive that includes both surface streets and freeway speeds. Mentally note how you feel and how it's performing while driving around. Finally, when you return to the dealer, sit there for a minute or two and make a note of how it's performing again under idle after having fully cooled and equalized the interior.


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## DGarrett (Jun 25, 2004)

bmw330zhpfan said:


> Now enough of that [email protected], most OEMs have a target air temperature at a known condition. Typically it is lowest temperature setting, at idle (vehicle not moving), recirculated air (max AC). After the system stabilizes, you want approx. 40 F from the ventilation system (measured @ the vent itself). You can pick up a refrigeration thermometer pretty cheap at a plumbing supply shop to verify this. With the introduciton of the CFC free refrigerants, the 40 F target has proven elusive. I know this because I converted a R12 system to R134a and noticed a performance difference immediately. I used to get condensation from the ventilation (it was painfully cold). After the conversion, it was typical of today's performance. The only way I could get 40 F was to drive the car (cooling air passing over the condenser). Was your older vehicle an R12 system? That could explain your performance difference.
> 
> Perhaps someone has a Bentley manual and can advise on the "target" temperature range for a 3 series AC system (as well as the test condition). I do not know the 3-series AC system in detail, but I suspect the expansion valve (that flashes the liquid to vapor) is a fixed orifice device and as such no adjustments are possible, but variable orifice systems are in production, however they are not adjustable.


ZHP makes some good points... when I moved to NC from northern Ohio I was driving a Mitsubishi Hibachi... er, a black Eclipse... and I hadn't fixed the ac b/c in OH, I just didn't need it. After moving to NC I had a few weeks of literally nothing to do after I took the bar exam and used the time to get myself EPA certified to work on mobile ac units and I spent 2 weeks rebuilding the ac from the ground up.

134a (tetrafluroethane) is a terrible refrigerant. R12 is/was UBER superior because it could transfer heat so much better, however, without any convincing research the EPA decided that R12 ate the ozone layer and mandated a change to 134a, probably at the behest of DuPont who had a vested interest in getting their product sold.

134a systems just can't do the chilling cold that we should all rightfully expect from our cars. Engineers have had to increase the size of the condenser (the radiator thing at the front of the car) in order to give the 134a more of a chance to condense properly, but it's still not enough. Also, the PAG lubricants used in 134a systems absorbs over 1,000 times the amount of moisture than the mineral oils used in R12 systems. Moisture=compressor failures=more $ for repairs=more profits. Government works!! :thumbup:

All ac systems are capable of only transferring heat from the inside of the car to the outside, and are limited by the capability of the referigant to transfer that heat. The Porches and VWs, I'm sure, didn't use 134a.

There are a lot of alternative refrigerants that are available, and are certified under the EPA SNAP program for mobile use, but it's hard to find a mechanic that knows anything about them. (a zeotropic blend like GJG-X8 "Cool top" or the new "Autofrost X8" can directly replace 134a and performs better than 134a, with an average 10F difference in air at the ducts.) For unknown reasons, no OEMs use anything other than 134a. Maybe they get a bulk discount from DuPont? You'll never convinve the BMW tech to put an alternative in for you. But, the point is that there are some other choices out there that may be worth examining if you're out of warranty or are beyond the free maintainance.

Has anyone taken any temps of their ac with the controls set to different temps? I've suspected that my system blends warm air with the chilled air. Maybe it's a mental thing, but it seems (subjectively) that I get colder air when I set the ac to 64F than when I set it to 72F... and I've noticed warm air at the floor ducts with the ac on on long trips.

A mass experiment is in order here: get a small digital therm and record the temps at the ducts for different settings (like at 72F or 64F or 50F...). Make sure that you record the lowest temps while the car is moving (i.e., the compressor is on - it should cycle on and off as you drive - and there's air moving through the condenser) so that you get good reliable results, AND approximately the outside temp b/c the outside temp does affect the performance of your system. (at 80F, moving you should get readings in the 40s or 30s; at 100F the best you *might* see is 60F) I'll do so for the next couple of days and let y'all know my results.

I've got a table somewhere of standard ac temps for 134a in relation to outside air temperatures... I'll dig it up and plug the results in to see how we're doing.


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