2011 HVAC

walendvay · 10-19-2014, 09:32 AM

Have a weird situation....

If the outside temp is cool (50s or 60s, let's say), I prefer to turn the A/C off, lower the temp inside the car to 60, direct the air to the front vents and maybe have the fan on low. Finally, the middle knob set on BLUE (cold)

Somehow, something has changed, perhaps with one of the more recent s/w updates earlier this year.....

The vents blow out relatively warm air.

Any ideas?

Also, I think I recall being able to set the min temp to 59'F. Now, the min is 60'F.

If I toggle on the a/c, I hear a vent change position. When I toggle it back off, I hear it change position back.

I think the blending door may be opening, even when the temp is at 60'F.

thoughts?

RhoXS · 10-19-2014, 10:39 AM

I have tried what you are suggesting in virtually every car I have owned over a lot of years; turn the compressor off and bring in outside air through the dash vents. In every case, the supply air from the vents is at a higher temperature than ambient.

I can only guess that there is either some air flow leaking through the heater core (likely IMO) or the duct work is warm and that transfers energy to the air. The energy to warm up the air must come from somewhere and these are the only two places I can think of.

Unless it is a day with very low humidity, even at lower outside temperatures, the compressor really needs to run to dehumidify the air. On a typical day (without very low humidity), even if the supply air coming through the vents is at a good temperature, it will not be dehumidified and you will not be as comfortable. BTW, this is why automatic systems typically run the compressors at all temperatures above the low 40s or so.

With manual systems I simply run the compressor and then adjust the temp control knob to reheat the cooled dehumidified air that just passed through the evaporator to my liking. In the X3 I just make sure the recirc button is set for outside air then just the temp setting accordingly.

walendvay · 10-19-2014, 11:58 AM

What is interesting, is I believe something had changed since one of the previous s/w updates on the car. At one time, ambient air was really close to air inside the car.

I agree with you regarding the need to dehumidify air. Fortunately (unfortunately?) I live in an area where the RH is in the single digits, so I really haven't a need to run the compressor to dehumidify.

Just curious if anyone else found that something changed with their rig......unless there is some magic coding setting that I could change, perhaps?

thanks.

10-19-2014, 09:32 AM	#1
walendvay First Lieutenant 52 Rep 343 Posts Drives: '11 F25 28i; '13 E84 35i Join Date: Jan 2011 Location: Pacific NW iTrader: (0)	2011 HVAC - cool air with A/C off Have a weird situation.... If the outside temp is cool (50s or 60s, let's say), I prefer to turn the A/C off, lower the temp inside the car to 60, direct the air to the front vents and maybe have the fan on low. Finally, the middle knob set on BLUE (cold) Somehow, something has changed, perhaps with one of the more recent s/w updates earlier this year..... The vents blow out relatively warm air. Any ideas? Also, I think I recall being able to set the min temp to 59'F. Now, the min is 60'F. If I toggle on the a/c, I hear a vent change position. When I toggle it back off, I hear it change position back. I think the blending door may be opening, even when the temp is at 60'F. thoughts?
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10-19-2014, 10:39 AM	#2
RhoXS Second Lieutenant 15 Rep 233 Posts Drives: 2002 Z3 3.0i + 2016 X3 28i Join Date: Jan 2012 Location: Florida iTrader: (0)	I have tried what you are suggesting in virtually every car I have owned over a lot of years; turn the compressor off and bring in outside air through the dash vents. In every case, the supply air from the vents is at a higher temperature than ambient. I can only guess that there is either some air flow leaking through the heater core (likely IMO) or the duct work is warm and that transfers energy to the air. The energy to warm up the air must come from somewhere and these are the only two places I can think of. Unless it is a day with very low humidity, even at lower outside temperatures, the compressor really needs to run to dehumidify the air. On a typical day (without very low humidity), even if the supply air coming through the vents is at a good temperature, it will not be dehumidified and you will not be as comfortable. BTW, this is why automatic systems typically run the compressors at all temperatures above the low 40s or so. With manual systems I simply run the compressor and then adjust the temp control knob to reheat the cooled dehumidified air that just passed through the evaporator to my liking. In the X3 I just make sure the recirc button is set for outside air then just the temp setting accordingly.
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10-19-2014, 11:58 AM	#3
walendvay First Lieutenant 52 Rep 343 Posts Drives: '11 F25 28i; '13 E84 35i Join Date: Jan 2011 Location: Pacific NW iTrader: (0)	What is interesting, is I believe something had changed since one of the previous s/w updates on the car. At one time, ambient air was really close to air inside the car. I agree with you regarding the need to dehumidify air. Fortunately (unfortunately?) I live in an area where the RH is in the single digits, so I really haven't a need to run the compressor to dehumidify. Just curious if anyone else found that something changed with their rig......unless there is some magic coding setting that I could change, perhaps? thanks.
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