7 - With the ignition key in the ON position, the heater and fan control switch at position 1 and the potentiometer ac-
tivated, check that current is reaching the 12-pin connector of the heating unit.
If not, proceed to carry out the following tests:
A - Check the voltage, applying the “+” prod of the meter to terminal 10 (blue/white - 1) and the “-” prod to terminals
4 and 5 (black leads - 1,5), as indicated in fig 4. The voltmeter should give a reading of 6.2 V approx. With the “-”
prod connected to earth, the reading should be 12 V.
B - Check the voltage, applying the “+”prod of the meter to terminal 11 (violet - 1) and the “-” prod to terminals 4
and 5 (black leads - 1, 5), as indicated in fig 4. The voltmeter should give a reading of 6.2 V approx.
C - If the meter fails to give any reading in steps A and B, turn the ignition key to the OFF position, unplug the 12-pin
connector from the heater unit and test for continuity at contacts 10 and 11 of the heater unit; the tester should give a
reading of 0 ohm. Conversely, if the resistance value is infinite, this means that the second thermal overload cutout
(100 °C) has remained open and the corresponding relay is disallowing the passage of current to the alternator field
coil.
8 - Insufficient ventilation (the revolutions of the electric fan unit are clearly affected by a low battery charge):
A - Fan control switch on speed I .
With the ignition key in the ON position (engine at standstill) and the fan control switch at position 1, the voltage at
contact 5 (black/white lead - 1, 5) should be 12 V, whereas the voltage at contact 4 (green lead - 2, 5) must be 6 V.
(These tests must be made with the second prod of the voltmeter connected to earth).
B - Fan control switch on speed II .
With the ignition key in the ON position (engine at standstill) and the fan control switch at position 2, the voltage be-
tween contact 1 (red/black lead - 1, 5) and earth should be 12 V, whereas the voltage between contact 4 (green
lead - 2, 5) and earth must be 8.5 V.
C - Fan control switch on speed III .
With the fan control switch at position III, the ventilation system relay is caused to cut in, with voltage at terminal 87
and contact at the connection of the red/black lead 2, 5 of the fan control switch. As the relay trips, voltage passes
to terminal 30 in association with contacts 1 and 2 of the 12-pin connector.
If the right ventilation is not obtained, test contact 4 (blue lead - 1) of the fan control switch and check that the voltage
is 12 V. Then test relay terminals 85 (brown/white lead - 1) and 86 (red/white lead - 1). If there is voltage registering
at these terminals, the relay cannot operate.
9 - The fan continues to operate at maximum speed whether the ignition key is in the ON or the OFF position (this
should happen only when the temperature of the air flow rises above 70 °C).
A - Unplug the 12-pin connector from the heating system and place the tester across contacts 7 (brown lead - 1)
and 8 (brown/white lead - 1) of the connector (heater side); a high value of resistance (ohms) should register. Con-
versely, if there is little or no resistance, then the first thermal overload cutout (70° C) is closed. If this happens
when the heater element is cold, the thermal overload device must be replaced.
B - If the first thermal overload cutout (70 °C) is open, remove the ventilation system relay; the fan unit should shut
off. If the fan does not stop, check continuity across terminals 87 and 30 of the relay. If the contact is found to be
open, then the relay is functioning correctly and can be retained. If not, replacement is required.
If the fan runs slow, check the wiring thoroughly.
systems
air conditioning
86
8
360
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