Suzuki XL7 2007 Service Manual page 1878

7A-64 Heating, Ventilation and Air Conditioning:
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at
the recirculation actuator.
2. Ignition OFF, test for less than 1.0 ohm of resistance
between the low reference circuit terminal 1 and
ground.
➢ If greater than 1.0 ohm, test the low reference
circuit for an open/high resistance. If the circuit
tests normal, replace the hvac control module.
3. Ignition ON, test for 4.8 to 5.2 volts between the 5 -
volt reference circuit terminal 3 and ground.
➢ If less than 4.8 volts, test the 5 -volt reference
circuit for a short to ground or an open/high
resistance. If the circuit tests normal, replace the
hvac control module.
➢ If greater than 5.2 volts, test the 5-volt reference
circuit for a short to voltage. If the circuit tests
normal, replace the HVAC control module.
4. Install a 3-amp fused jumper wire at the signal circuit
terminal 2, test for greater than 5 volts. Toggle the
jumper wire between the low reference circuit
terminal 1 and the 5-volt reference circuit terminal 3.
➢ If the position signal parameter is less than 5 volts,
test the signal circuit for a short to voltage, or an
open/high resistance. If the circuit tests normal,
replace the HVAC control module.
5. Ignition ON, after 30 seconds verify that a test lamp
illuminates between control circuit A terminal 4 and
B+.
➢ If the test lamp does not illuminate, test the control
circuit for a short to voltage or an open/high
resistance. If the circuit tests normal, test the B+
circuit of the HVAC control module for a short to
ground, high resistance, or an open. If the circuit
tests normal, test the HVAC control module ground
circuit for a high resistance or an open. If the circuit
tests normal, replace the HVAC control module.
6. Ignition OFF, verify that a test lamp does not
illuminate between control circuit A terminal 4 and
B+.
➢ If the test lamp illuminates, test the control circuit
for a short to ground. If the circuit tests normal
replace the HVAC control module.
7. Ignition ON, after 30 seconds verify that a test lamp
illuminates between control circuit B terminal 5 and
B+.
➢ If the test lamp does not illuminate, test the control
circuit for a short to voltage or an open/high
resistance. If the circuit tests normal, test the B+
circuit of the HVAC control module for a short to
ground, high resistance, or an open. If the circuit
tests normal, test the HVAC control module ground
circuit for a high resistance or an open. If the circuit
tests normal, replace the HVAC control module.
8. Ignition OFF, verify that the test lamp does not
illuminate between control circuit B terminal 5 and
B+.
➢ If the test lamp illuminates, test the control circuit
for a short to ground. If the circuit tests normal
replace the HVAC control module.
9. If all circuits test normal, replace the recirculation
actuator.
Repair Instructions
Perform the "Diagnostic Repair Verification - Vehicle
Diagnostic Information: " after completing the diagnostic
procedure.
• "Control Module References: " for HVAC setup,
programming, and replacement.
• "Recirculation Actuator Replacement"
Inside Air Temperature Sensor Malfunction
Diagnostic Instructions
• Perform the "Diagnostic System Check - Vehicle
Diagnostic Information: " prior to using this diagnostic
procedure.
• Review "Strategy Based Diagnosis: " for an overview
of the diagnostic approach.
• "Diagnostic Procedure Instructions - Vehicle
Diagnostic Information: " provides an overview of
each diagnostic category.
Circuit/System Description
The HVAC control module supplies the inside air
temperature sensor with a low reference circuit and 5-
volt signal circuit. The HVAC control module determines
the voltage drop across the sensor, which is proportional
to temperature. As the air temperature increases, the
sensor resistance decreases and the voltage signal
decreases. As the air temperature decreases, the
sensor resistance increases and the voltage signal
increases. The inside air temperature sensor assembly
has an internal fan that draws air across the sensor and
is controlled by the HVAC control module. The internal
fan motor is connected to body ground.
Diagnostic Aids
If DTCs B0158, and B3933 are all set inspect the signal
circuit for a short to voltage. If the circuit tests normal
replace the HVAC control module.
Reference Information
Schematic Reference
"HVAC Schematics"
Connector End View Reference
"HVAC Connector End Views"
Description and Operation
"Air Temperature Description and Operation"