Subaru 2002 IMPREZA Service Manual page 2527

2. General Description
A: CAUTION
1) Never connect the battery in reverse polarity.
• The Auto A/C control module will be destroyed
instantly.
2) Do not disconnect the battery cables while the
engine is running.
• A large counter electromotive force will be gener-
ated in the alternator, and this voltage may damage
electronic parts such as A/C control module.
3) Before disconnecting the connectors of each
sensor and the A/C control module, be sure to turn
off the ignition switch.
• Otherwise, the Auto A/C control module may be
damaged.
4) Every Auto A/C-related part is a precision part.
Do not drop them.
5) Airbag system wiring harness is routed near the
A/C control panel (A/C control module) and junction
box.
CAUTION:
• All airbag system wiring harness and con-
nectors are colored yellow. Do not use electri-
cal test equipment on these circuits.
• Be careful not to damage the airbag system
wiring harness when servicing the A/C control
panel (A/C control module) and junction box.
GENERAL DESCRIPTION
B: INSPECTION
Before performing diagnosis, check the following
items which might affect engine problems.
1. BATTERY
1) Measure the battery voltage and specific gravity
of electrolyte.
Standard voltage: 12 V
Specific gravity: Above 1.260
2) Check the condition of the fuses for A/C, heater
and other fuses.
3) Check the condition of the harnesses and har-
ness connectors connection.
2. ASPIRATOR HOSE
1) Make sure that the aspirator hose is securely
connected to the heater unit by inserting a hand
from the driver's compartment and secure as nec-
essary.
2) Turn the ignition switch to ON and push the
"A/C" switch.
3) Turn the temperature control dail to maximum
hot position.
4) Turn the air flow control dial to "DEF" position.
5) Turn the fan speed control dial to 4th position.
6) Firmly hold a thin thread (b) in front of the in-ve-
hicle sensor suction port (a) for the auto A/C control
unit and check that the thread moves towards the
port indicating that air is being sucked into the port.
NOTE:
• Ensure the thread does not get sucked into the
port.
• Hold the thread approx. 5 mm (0.02 in) away
from port when the suction force is not very strong.
AC-3
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
HV0027