Relay - wsm STW37 Workshop Manual

STW34, STW37, STW40, WSM

[2] RELAY

Remove the outer roof and the relays are visible at
the ceiling rear of the cabin: blower relay (3) and
compressor relay (1). When the blower fan is adjusted
for the air flow rate, the blower relay (3) is activated by a
signal from the fan switch on the control panel.
Among the air conditioner components, current flows
to the blower motor (10) and magnetic clutch. If all of
these current were to be passed through the main switch
(6) and supplied, the current would be too large for the
main switch (6) so that there will be danger or burning
out the main switch contact. If the current were to be
passed directly from the battery (5), forgetting to turn off
the blower motor (10) could result in a discharged battery
(5).
To protect against such trouble, relays have been
provided. These relays have been made so that when
current flows through its coil, the contact close to supply
the power from the battery (5). By employing these
relays, the current flowing through the main switch (6)
has been decreased as only a small current is required
to actuate the relay. Thus there will be no danger of
burning out the switch contact, and when the main switch
(6) is opened, the relay contact will open at the same
time. This action stops the current flow in the air
conditioner circuit so that there will also be no chance of
the battery discharging.
(1) Compressor Relay
(2) Wiper Relay
(3) Blower Relay
(4) Defogger Relay
(5) Battery
(6) Main Switch
(7) Combination Switch
(8) Defogger Switch
10-M10
CABIN
(9) Defogger
(10) Blower Motor
(11) A/C Unit
(12) Pressure Switch
(13) Compressor
(14) Washer Tank Motor
(15) Wiper Motor Switch
(16) Wiper Motor
9Y1211109CAM0014US0
KiSC issued 11, 2014 A