settings.
2) Set blower/fan on high speed. Close doors and windows.
Insert thermometer in center vent. Operate system for 20 minutes to
allow system to stabilize. Measure temperature.
3) Discharge air temperature must be 37-44
F (3-7C) at
center vent, with high side and low side pressures within
specification. See A/C SYSTEM SPECIFICATIONS table at beginning of
article.
A/C CONTROL UNIT (ACCU)
1) Locate A/C Control Unit (ACCU) on top of evaporator case
and disconnect 10-pin connector. Inspect connector and wiring for
damage. Turn ignition and A/C on. Set temperature control to maximum
cooling and blower switch to high. Using a DVOM set to appropriate
test function, inspect harness side of connector. See Fig. 3. Go to
next step. If all test readings are as specified, replace ACCU.
2) Terminal No. 1 (Green/Yellow wire) is ACCU output. With
A/C and blower motor on, battery voltage should be present when ACCU
has received signals from pressure and temperature sensors confirming
A/C operation is okay.
3) Terminal No. 3 (Green/Blue wire) is ACCU power supply whe\
n
A/C switch is in A/C mode. With ignition and blower on, and A/C switch
at second level setting, battery voltage should be present.
4) Terminal No. 5 (Green/Red wire) is ACCU power supply when\
A/C switch is in ECONO mode. With ignition and blower on, and A/C
switch at first level setting, battery voltage should be present.
Terminals No. 2 and 7 (Black wire) are ACCU grounds. There should be
zero volts at all times.
5) Turn ignition off. Reconnect 10-pin connector. Turn
ignition on. Turn A/C on. Set temperature control to maximum cooling
and blower switch to high. Backprobe 10-pin connector. Go to next
step. If all test readings are as specified, replace ACCU.
6) Terminal No. 10 (Blue/White wire) is air thermosensor
power supply. With ignition, blower and A/C on, approximately 5.5
volts should be present.
7) Terminal No. 8 (Blue/Yellow wire) is air thermosensor
signal. When temperature of evaporator outlet portion is 77
F (25C),
there should be approximately 3.6 volts present.
8) Terminal No. 4 (White/Blue wire) is air inlet sensor powe\
r
supply. With ignition, blower and A/C on, approximately 5.5 volts
should be present.
9) Terminal No. 9 (Yellow/Green wire) is air inlet sensor
signal. When temperature of evaporator outlet portion is 77
F (25C),
there should be approximately 1.5 volts present.
Fig. 1: Testing ACCU
Courtesy of Mitsubishi Motor Sales of America.
A/C SWITCH