UPDATE: YES it's holding refridgerant
and on a cool temp day (60's) it blew cold for
over an hour.

Hi all

2005 Audi A4 Avant, Silver, V6, 6spd, quattro, 87K mi

Current symptom:
A/C blows cold for short time, then "Econ" lights and A/C blows hot


Original AC problem occured Summer 2012

"Econ" light illuminates, AC blows hot air,
manual says this indicates loss of refridgerant pressure

Original diagnosis was seized compressor (approx 75K miles),
compressor replaced, ice-cold air for 20 minutes,
then "Econ" light again, AC blows hot

Some research suggests replacing "thermo-switch" on driver's
side of condensor, as they fail over time
switch replaced, ice-cold air for 15-20 minutes,
then "Econ" light again, AC blows hot

Refridgerant recharged with dye (Aug 2012), then life and fall
temps got in the way ...

Now, AC blows cool for a while (longer with lower ambient temps,
sooner with higher temps), then "Econ" lights, hot air
Yet, it always blows cold at startup?
Does this imply there's still refridgerant in system
and the issue is electrical/sensor?

Don't yet know if it's holding refridgerant, if dye still visible,
or if any codes thrown.

Any ideas before I give up and pay the dealer/mechanic
for a diagnosis?

Thanks
Joe

 

Troubleshoot Automotive Air Conditioning Problems

 

Broke down* and went to dealer to read codes -
no leaks, but bad "High Pressure Sensor" 3R0-959-126
$118 for the part $20 R134 $75 labor

(*really did break down 100 miles from home -
alternator failed. $565 + labor for an alternator?!?!)