Aircon

[OGiii]

The Aircon on my MY99 996 doesn't seem to be anywhere near as cold as any other car I've had.

It blows well and the climate control seems to work because it does control the level of the blowing automatically.

The air coming through the vents is cooler than the outside but it's not ice cold.

Is this normal?

Thanks

[dvdude]

My (limited) experience with german cars tends to indicate that AC is generally not as cold as others. My Passat was downright warm, the A4 was a little better. That said, the C4's AC seems to run very cold.

If you really think there's a problem, you could get it measured and work from there.

[bet]

In my experience your A/C is not normal and you should have it serviced. The A/C on my 996 blows out ice cold air. So cold that the vents have to be positioned to not blow directly on me once the cabin cools down. The same was true of my former boxster.

Edited June 23, 2005 by bet

[1999Porsche911]

Outlet air should be around 50F or colder.

[wwest]

Modern day climate control systems, including the 996, use an airflow "remix" method so that the airflow exiting the system isn't discomforting.

ALL of the system airflow first passes through the A/C evaporator and is chilled to the MAX. Then, some or all of that airflow is routed through a reheat cycle, diverted to flow through the heater core. Then both airflows are remixed.

The base idea, once the cabin temperature has reached or is very close to your setpoint, say 72F, the system airflow temperature will be just below that (~65F) to prevent discomfort and now flow volume ("..it does control the level of the blowing automatically...") will be the principle method for maintaining your comfort level.

It is well known within the A/C industry that the actual cooling level of the refrigerant heat exchange process cannot be modulated. The refrigerant "boils" at ~20F and any airflow exposed to that for a period of time will soon be at that level.

Most systems regulate the refrigerant flow such that the A/C evaporator surface temperature remains at or close to ~35F but NEVER declines below the freezing level wherein it would soon be blocked with ice.

If you want to experience airflow at its maximum cooling level then turn the system to minimum temperature and the lowest blower speed before the engine water jacket rises to operating temperature.

Edited June 23, 2005 by wwest

[PorschePRH]

My 03 blows as cold as any car I have had (and I have had a bunch!)...

Get it check by someone that knows what they are doing (hint: there are percetage wise very few that do).

[Hroussard]

I don't know if this helps but I also have a C2 1999 and my A/c just did not chill. Investigation by Carlsen in Redwood City showed that the expension valve was not working. The part number is 99657392901 and together with some o-rings that valve was about 180 bucks. They had to empty the a/c system and refill it which cost additional. The total job took abour 3 hours or so.The air is now ICE COLD!!

Cheers

HarryR

[wwest]

One thing, IMPORTANT!, to remember.

Once the passenger cabin reaches or nears the temperature setpoint reach up and select dash outlet ONLY! Or dash and footwell if you wish and but not in recirc mode.

Otherwise a major portion of the system's cooling airflow will be needlessly routed toward, and thereby WASTED, to the interior surface of the windshield.

Flaw in the design that Porsche refuses to address even though VW has for the Touareg.

Edited June 24, 2005 by wwest

[wwest]

I don't know if this helps but I also have a C2 1999 and my A/c just did not chill. Investigation by Carlsen in Redwood City showed that the expension valve was not working. The part number is 99657392901 and together with some o-rings that valve was about 180 bucks. They had to empty the a/c system and refill it which cost  additional. The total job took abour 3 hours or so.The air is now ICE COLD!!

Cheers

HarryR

<{POST_SNAPBACK}>

If the outlet airflow is ice cold once the passenger cabin is near the setpoint then someone has shorted out one of the system sensors.

[OGiii]

Thanks for all the replies.

I'll get it checked over.

Cheers

OG

[viper501]

The Aircon on my MY99 996 doesn't seem to be anywhere near as cold as any other car I've had. 

 

It blows well and the climate control seems to work because it does control the level of the blowing automatically. 

 

The air coming through the vents is cooler than the outside but it's not ice cold. 

 

Is this normal? 

 

Thanks

<{POST_SNAPBACK}>

Check the a/c condensor in the front bumper opening. As pointed out by someone else, that puppy can get full of nasty debris resulting in restricted airflow through the condenser and poor cooling in the car. :thumbup:

[OGiii]

Thanks Viper

Where is the front bumper opening - probably being thick here but I can't see anything :unsure:

[slbates]

I have a 1999 C2 so I can give you some numbers for a car of this age with 97k miles...

OAT 90 degrees

A/C set at 70 degrees - outside air source (not on recirc)

windows up all day due to threat of T-storms (end up sunny)

center vent temp after 10 minutes of operation 50.2 degrees

cabin temp after 15 minutes of operation 72.3 degrees

Note: center vent temp measured with Fluke meter probe inserted about 2 inches into vent. Hope this gives you an idea

[wwest]

Again, the Porsche climate control system uses a airflow reheat/remix method so as to not discomfort the driver/passenger with airflow that is TOO cold.

ALL air flows through the A/C evaporator and is CHILLED to as close to 33F as time, airflow speed, will allow. A portion, or all, of this CHILLED airflow is then diverted through the heating section and then all airflow is remixed before exiting the system.

If the cabin is at 85F (or if the sunlight radiation sensor indicates BRIGHT sunlight) and your setpoint is 72 the system airlfow will be COOL, but not so much so as to be discomforting. As the cabin temperature declines to 72F the system airflow will become warmer until it is just cool enough (~68F??) to sustain the cabin at 72F.

You can defeat the reheat/remix system by calling for max cooling and then use the blower speed to manually regulate your comfort level.

You can also increase the A/C efficiency by adding a manual flow control valve (Home Depot) in line with the heater hose just to the left of the battery under the bonnet.

Both of the above methods will result in less cycling of the A/C compressor, improving MPG and decreasing the heat load on the engine cooling radiators.