A/C Clutch Does Not Engage
Test
No.
Test
Test Procedure
Test Result
Action
3
Check if A/C request
is being sent.
Connect PC to vehicle and open
the Behr CDTC Blend Air HVAC
System DataLink Monitor
template. Do the following:
•
Start the engine.
•
Set the blower to any
speed except off.
•
Set the air selection
switch to face mode.
•
Press the A/C button; the
light should be on.
Observe the A/C request annun-
ciator in the template. The A/C
request signal should be active
and the A/C compressor should
engage when the previous condi-
tions are met and the following
conditions are met:
•
Evaporator sensor is
above 44°F (7°C).
•
Engine speed above 450
rpm. See template.
•
Low air pressure signal is
not being broadcast by
the instrument cluster. See
template.
A/C request signal is
active.
See
A/C request signal is
not active.
Go to test no. 4
.
4
Check evaporator
sensor.
Note the ambient air tempera-
ture. Measure the resistance of
the evaporator temperature sen-
sor and compare the reading
with the value in
or
. The reading should co-
rrespond to a temperature ap-
proximately equal to the ambient
temperature.
NOTE: The evaporator sensor
temperature must be above 44°F
(7°C) before the FCU will send
the A/C request signal to the A/C
clutch relay. Therefore the
sensor resistance must be below
approximately 6500 ohms. See
or
. Also see
Less than 6500 ohms
Check wiring between FCU and
evaporator temperature sensor. If
okay and all other inputs are
met, such that the A/C request
signal should be sent, then
replace the FCU.
Go to test no.
5
.
More than 6500ohms
The FCU is not sending an A/C
request signal because the
sensor is indicating the
temperature is below 44°F (7°C).
If temperature is known to be
well above this temperature, then
replace the sensor.
Go to test
no. 5
.
Heater and Air Conditioner Troubleshooting
83.00
Symptom Driven Diagnosis
122SD and Coronado Workshop Manual, Supplement 9, June 2014
350/7
