[s-cars] Climate Control - Damn the Snowflake

[Fred Munro]

Hmm, ice on the condenser is bad, Manny. The condenser is supposed to be
hot. The compressor takes cooled refrigerant gas from the condenser and
compresses it to liquid under pressure. The high pressure liquid passes
through an orifice at the evaporator and turns back to gas in the low
pressure zone in the evaporator, absorbing heat as it changes state from
liquid to gas. The hot low pressure gas then goes to the condenser where it
releases heat to the airflow and goes back to the compressor.

If you are getting ice on the condenser, that would tell me you have a
restriction in the condenser that is acting as an orifice and allowing the
refrigerant to pass from a high to low pressure zone in the condenser,
absorbing enough heat to freeze moisture. A low refrigerant charge can
freeze up the evaporator because the pressure drop across the orifice is too
high and too much heat is absorbed ( the low pressure side pressure is too
low). A high refrigerant charge usually means the low side pressure is too
high and the cooling effect is impaired (the pressure drop across the
orifice is not high enough). I suppose a too high charge could result in
high pressure gas entering the condenser and may make it prone to freezing
if there is a restriction there. I'm just speculating here, never had this
problem.

Fred

-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com]On Behalf Of
manuelsanchez at starpower.net
Sent: June 20, 2007 9:21 PM
To: djdawson2 at aol.com; rit_bellis at hotmail.com; s-car-list at audifans.com
Subject: Re: [s-cars] Climate Control - Damn the Snowflake


What if I were to tell you that I noticed once after a loooong summer
highway run in moderate temps (mid 80's), say about 5 hours of constant
running, I found Ice on the condensor?

-manny

---- Original message ----
>Date: Wed, 20 Jun 2007 17:27:11 -0400
>From: djdawson2 at aol.com
>Subject: Re: [s-cars] Climate Control - Damn the Snowflake
>To: rit_bellis at hotmail.com, manuelsanchez at starpower.net,
s-car-list at audifans.com
>
>   Again... higher temps equal higher pressures.  If
>   your A/C is cutting out only at higher outside
>   temps, my bet is that you're not pushing enough air
>   accross the condensor.  This could be for several
>   reasons... fan clutch... electric fan... or a
>   condensor plugged with debris.
>
>   -----Original Message-----
>   From: Rit Bellis <rit_bellis at hotmail.com>
>   To: djdawson2 at aol.com; manuelsanchez at starpower.net;
>   s-car-list at audifans.com
>   Sent: Wed, 20 Jun 2007 2:19 pm
>   Subject: RE: [s-cars] Climate Control - Damn the
>   Snowflake
>
> I too am interested in the answer to the snowflake question.  My 93 s4
quit
> cooling when it hit 84 degrees or higher all last summer. Then, the car
> self-healed over the winter.  (only change being a missing belly pan.)
this
> summer (audi gods and thor permitting) the snowfake has kept right on
> working as the temps hit 95 degrees and higher.  I have long suspected the
> uper limit temp sensor, but is there another possible culprit?  Thanks!
>
> -----Original Message-----
> From: s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com] On Behalf Of djdawson2 at aol.com
> Sent: Wednesday, June 20, 2007 12:59 PM
> To: manuelsanchez at starpower.net; s-car-list at audifans.com
> Subject: Re: [s-cars] Climate Control - Damn the Snowflake
>
>
> High pressure, low pressure, and freezing are three I know off the top of
my
> head.  If the A/C works fine under less than extreme conditions, I would
> wonder if high pressure is the problem.  I would then look into the fan
> clutch and electric fan operation... these are what keep high pressures
from
> developing.
>
>
> -----Original Message-----
> From: manuelsanchez at starpower.net
> To: s-car-list at audifans.com
> Sent: Wed, 20 Jun 2007 12:47 pm
> Subject: [s-cars] Climate Control - Damn the Snowflake
>
>
>
> Fellow S-heads,
> All this climate control talk has prompted me to ask the following: What
> causes the Snowflake to turn off by itself: 1. Low Refrigerant (some fail
> safe mode to spare the compressor some unsightly
> eath)
> 2. Failing Climate Control Head
> 3. Other
> She tho must be obeyed is annoyed with me, as my car seems to suffer from
> the
> nowflake and compressor shutting off when it's Africa hot outside. I, and
> wifey, thank you. -Manny 5.5 UrS6 Avant (Flakey Snowflake)
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