Isuzu 1999 RODEO Workshop Manual page 68

1A–40 HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
When the air conditioning switch and the fan control knob
(fan switch) are turned on with the engine running, current
flows through the thermostat and the compressor relay to
activate the magnetic clutch.
The air conditioning can be stopped by turning of the air
conditioning switch or the fan control knob (fan switch).
However, even when the air conditioning is in operation,
the electronic thermostat, the pressure switch or the
Magnetic Clutch Does Not Run
Step
1 Are No. EB-5 (10A) fuse and No. EB-4 (20A) fuse OK?
2 Are heater (X-6), thermostat (X-5), and compressor (X-4) relays
OK?
3 Is pressure switch OK?
4 Are air conditioning switch and fan control lever (Fan Switch) OK?
5 1. Turn the ignition switch "ON" (Engine is running).
2. Air conditioning switch and fan control lever (Fan Switch)
"ON".
3. Check to see if battery voltage is present at chassis side
connector terminal No. E3-1.
Is there a battery voltage?
6 Check to see if continuity between compressor side connector
terminal No. E3-1 and the magnetic clutch side connector
terminal.
Is there a continuity?
7 Check to see it battery voltage is present at chassis side
connector terminal No.I24-2.
Is there a battery voltage?
8 Check to see if battery voltage is present at chassis side
connector terminal No. C11-1
Is there a battery voltage?
9 1. Disconnect thermostat relay (X-5).
2. Check to see if battery voltage is present at the chassis side
relay terminal NO. X5-5
Is there a battery voltage?
10 Check to see if voltage (approx. 10V) is present between chassis
side relay terminal No. X5-2 and No. X5-4.
Is there a battery voltage?
11 1. Reconnect thermostat relay and disconnect compressor relay
(X-4).
2. Check to see if battery voltage is present at the chassis side
relay terminal No. X4-5.
Is there a battery voltage?
12 Check to see if continuity between chassis side relay terminal No.
X4-1 and the chassis side connector terminal No. E3-1.
Is there a continuity?
Powertrain Control Module (PCM;V6-3.2L)/ Engine
Control Module (ECM;L4-2.2L) is used to stop the air
conditioning temporarily by turning off the magnetic clutch
in the prearranged conditions to reduce the engine load
which is being caused by the rise in the engine coolant
temperature, and the acceleration of the vehicle, etc.
For the inspection of the relays, switches and units in the
table, refer to "Individual Inspection" in this section.
Action Yes
Go to Step 2 Replace
Go to Step 3 Replace
Switch defective
or insufficient
refrigerant.
Go to Step 4
Go to Step 5 Replace
Go to Step 6 Go to Step 7
Magnetic clutch Compressor
defective. defective.
Open circuit
between No.EB-5
(10A) fuse and
Go to Step 8
No. I24-2.
Open circuit
between No.I24-1
Go to Step 9 and No. C11-1.
Open circuit
between No.
EB-5 and C11-2
(10A) fuse and
No.X5-5.
Go to Step 10
Go to Step 11 Go to Step 17
Open circuit
between No.
EB-5 (10A) fuse
Go to Step 12 and No. X4-5.
Go to Step 13 Open circuit.
No