AC Problems - Low Pressure 93 90q w/ 134A

Avi Meron avim at
Thu Aug 9 19:26:24 EDT 2001

How things are done in WA is not really relevant to the discussion!
Technicians do everything "AS FAST AS POSSIBLE" that is the only motto that
counts (for most technicians, I am sure there are exceptions, but I haven't
seen many!)!

Correct procedure is to charge is through the high side; at certain
temperatures the refrigerant could possibly be pushed to the system as
LIQUID, which may cause "liquid slugging".  The compressor will violently
react to liquid and possibly could get damaged! Of course I am not
discussing "do it yourself types" that is an entirely different matter!

I can also tell you that in 99+% of the time you can charge it from any side
you want, and it will still be OK (that is reality, I see it ALL the time).
It could be that Audi knowing that almost ALL technicians would charge the
system from the WRONG side only has a high side service port.  Maybe, Audi
was trying to prevent compressor failures from liquid slugging by doing

You all take care now,

-----Original Message-----
From: quattro-admin at [mailto:quattro-admin at]On
Behalf Of Dave Glubrecht
Sent: Thursday, August 09, 2001 1:22 PM
To: avim at; Andrew Lundy
Cc: Quattro
Subject: Re: AC Problems - Low Pressure 93 90q w/ 134A

It is most common to charge from the LOW side here in WA state.
There are several advantages to high side charging (mostly speed) but I do
not even know anyone who charges through the high side.
When charging through the low side you must make sure you are charging as a
vapor which means that your source will require heat input.  It takes longer
to put the proper volume in as a vapor than as a liquid.  The system must
also be running to change it back to a liquid in order to store the proper
amount in the system.
As you state, liquid will not compress and care must be taken to ensure that
only vapor is introduced to the system to prevent system damage.
  Dave G    (WA state freon cert.)

----- Original Message -----
From: Avi Meron <avim at>
To: Andrew Lundy <fast928 at>
Cc: Quattro <quattro at>
Sent: Thursday, August 09, 2001 1:04 PM
Subject: RE: AC Problems - Low Pressure 93 90q w/ 134A

> Actually Andrew, in AC are supposed to charge
> the high side NOT the low side!
> BUT you CAN NOT have the car running!
> The ACR 4 or others (AC charging machines) have a small compressor that
> force-feeds the refrigerant to the AC system!
> Reason is (I thought you will never ask!) is to PREVENT liquid charging to
> the compressor (the refrigerant is in liquid form in the tank), the
> compressor will not compress liquid "too well".
> Take care, now,
> Avi
> -----Original Message-----
> From: quattro-admin at [mailto:quattro-admin at]On
> Behalf Of Andrew Lundy
> Sent: Tuesday, August 07, 2001 10:30 AM
> To: Robert Bauer; Quattro List
> Subject: Re: AC Problems - Low Pressure 93 90q w/ 134A
> <SNIP> How does one recharge a system with only a high pressure port?
> With the use of a special machine designed for this purpose!!
> ---
> Andrew Lundy
> fast928 at
> 90 80q
> 95 90q

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