How does climate control AC work?

In a car with climate control, I set temperature to say 80. Does that
mean the AC is running with full power but it mixes with some hot air
or hot coolant to warm it up to the final temperature 80, or the 80
degree is maintained in a more economical way? I mean, does it run AC
for a few minutes, stop so the inside temperature is about to go up,
and then the AC starts again, like the house AC does?

Yong Huang

Yong Huang wrote:
> In a car with climate control, I set temperature to say 80. Does that
> mean the AC is running with full power but it mixes with some hot air
> or hot coolant to warm it up to the final temperature 80, or the 80
> degree is maintained in a more economical way? I mean, does it run AC
> for a few minutes, stop so the inside temperature is about to go up,
> and then the AC starts again, like the house AC does?
>
> Yong Huang

Depends on which manufacturer your talking about. It also depends on
outside temperatures and what you set the temperature at.

For instance if the outside temperature is 110 and you set the interior
at 80 on a GM system it will simply cycle the A/C to keep it at that temp.
If it was 60 outside it would simply cycle the heat on/off through the
blend doors.

--
Steve W.
Near Cooperstown, New York

On Jun 4, 10:17 pm, "Steve W." > wrote:
> Yong Huang wrote:
> > In a car with climate control, I set temperature to say 80. Does that
> > mean the AC is running with full power but it mixes with some hot air
> > or hot coolant to warm it up to the final temperature 80, or the 80
> > degree is maintained in a more economical way? I mean, does it run AC
> > for a few minutes, stop so the inside temperature is about to go up,
> > and then the AC starts again, like the house AC does?
>
> > Yong Huang
>
> Depends on which manufacturer your talking about. It also depends on
> outside temperatures and what you set the temperature at.
>
> For instance if the outside temperature is 110 and you set the interior
> at 80 on a GM system it will simply cycle the A/C to keep it at that temp.
> If it was 60 outside it would simply cycle the heat on/off through the
> blend doors.
>
> --
> Steve W.
> Near Cooperstown, New York

Thanks, Steve. My cars are Honda, one Civic one Odyssey. I only use A/
C in summer. Assume the outside temperature is at least 90. I guess in
this case the A/C cycles on and off?

Yong Huang

Yong Huang wrote:
> On Jun 4, 10:17 pm, "Steve W." > wrote:
>> Yong Huang wrote:
>>> In a car with climate control, I set temperature to say 80. Does that
>>> mean the AC is running with full power but it mixes with some hot air
>>> or hot coolant to warm it up to the final temperature 80, or the 80
>>> degree is maintained in a more economical way? I mean, does it run AC
>>> for a few minutes, stop so the inside temperature is about to go up,
>>> and then the AC starts again, like the house AC does?
>>> Yong Huang
>> Depends on which manufacturer your talking about. It also depends on
>> outside temperatures and what you set the temperature at.
>>
>> For instance if the outside temperature is 110 and you set the interior
>> at 80 on a GM system it will simply cycle the A/C to keep it at that temp.
>> If it was 60 outside it would simply cycle the heat on/off through the
>> blend doors.
>>
>> --
>> Steve W.
>> Near Cooperstown, New York
>
> Thanks, Steve. My cars are Honda, one Civic one Odyssey. I only use A/
> C in summer. Assume the outside temperature is at least 90. I guess in
> this case the A/C cycles on and off?
>
> Yong Huang

Yes.

--
Steve W.

Yong Huang wrote:
> In a car with climate control, I set temperature to say 80. Does that
> mean the AC is running with full power but it mixes with some hot air
> or hot coolant to warm it up to the final temperature 80, or the 80
> degree is maintained in a more economical way? I mean, does it run AC
> for a few minutes, stop so the inside temperature is about to go up,
> and then the AC starts again, like the house AC does?
>
> Yong Huang


GENERALLY it works as follows:

The compressor runs just enough to maintain the temperature of the
evaporator core at about 40 degrees F. at all times.

The interior fan runs at a speed sufficient to maintain the interior
temperature at whatever you set it.

SO, the temp setting you pick *does* affect the cycling of the
compressor, but only indirectly. If you pick a colder setting, the fan
will speed up, which warms the evaporator core more rapidly, which makes
the compressor run more in order to maintain the 40-degree setpoint of
the evaporator core. Picking a warmer setting slows the fan, which slows
the removal of heat from the evaporator, which mens the compressor runs
less.

When the ambient temperature outside the car falls below your setpoint,
AND the minimum fan speed is reached, the control system starts blending
warm air to maintain your set temperature.

Its done that way mainly for humidity control. Keeping the evap core
really cold does a better job of de-humidifying the air running the fan
faster an allowing the core to get warmer.