100CS Quattro Wagon V6-2.8L (AAH) (1992)
Control Module HVAC: Technical Service Bulletins
A/C - Climate Control Common Problems
Group: 87
Number: 94-09
Date: August 1, 1994
Subject:
A/C Climate Control Common Problems
Models(s):
100
m.y. 92-94
90
m.y. 93-94
Important Notes:
1. -
Manual A/C = Non-permanent memory Automatic Climate Control = Permanent memory
2. -
Control heads for Audi 90 and 100 MUST not be interchanged, even though they look identical and will fit in either vehicle.
3. -
Refer to the applicable Technical Bulletin for information on R-134a component replacement. See the following section, Reference Materials.
Note:
The VIN breakpoint listed in the parts microfiche is in error, order parts by SYSTEM (R-12 or R-134a), not by VIN. System information can
be found in the remarks column in the fiche.
4. -
When diagnosing an A/C problem where the compressor clutch will not engage, compressor shut-off conditions are as important as DTC. They
tell you why the control head, (on automatic climate control systems), or the compressor clutch control module, (on manual A/C systems), shut
the compressor clutch off. This information can be found in:
- Manual A/C:
Measuring Value Block, Function 08,
Display Group 1, Channel 1
- Automatic Climate Control:
Measuring Value Block, Function 08,
Display Group 1, Channel 1
Control Head Diagnostic Display,
Channels 1 and 52.
5. -
There are at least 5 reasons the compressor clutch will shut-off and not register a DTC:
- A/C system is manually turned off.
- Ambient temperature too low.
- Engine overheat signal from the 4 terminal multi-function temperature sensor.
- Load signal from the engine control unit (shut-off for up to 12 seconds).
- Kickdown signal from TCM (shut-off for up to 12 seconds).
Reference Materials: