Volkswagen Passat 1995 Official Factory Repair Manual page 4206

A/C refrigerant system, troubleshooting
http://ebahn.bentleypublishers.com/vw/servlet/Display?action=Goto&type=repair&id=VW.B4.HA01.87.6
Checking
- Start engine.
- Set temperature control to maximum "cold".
- Press A/C button and select second blower
speed.
- Adjust air distribution to instrument panel
outlets.
- Insert thermometer into center instrument panel
outlet.
- Raise engine speed to approximately 1500
RPM.
Specified result
With normal humidity and outside (ambient)
temperature between 20 -25 C (68 -77 F),
system is sufficiently charged if air temperature
from center instrument panel vent drops below
10 C (50 F) within one minute.
For higher ambient temperatures and/or higher
humidity, specified air temperature from center
instrument panel vent can be slightly higher.
Page 9 of 10
87-112
12/7/2004