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Groundsmaster 5900/5910 Page 5 -- 53 Electrical System
Air Conditioning Relay (Groundsmaster 5910)
A relay is used to control the air conditioning electrical
power circuit on the Groundsmaster 5910. When ener-
gized by the air conditioning switch, the relay provides
current for the air c onditioning components. The relay is
attached to the cab headliner above the switch panel.
Testing
1. Make sure ignition switch is OFF. Remove key from
ignition switch.
2. Remove screws that secure switch panel to headlin-
er in cab. Locate relay and disconnect the machine wire
harnessconnectorfromtherelay.Removerelay for eas-
ier testing.
NOTE: Prior to taking small resistance readings with a
digital multimeter, short the meter test leads together.
The meter will display a small resistance value (usually
0.5 ohms or less). This resistance is due to the internal
resistance of the meter and test leads. Subtract this val-
ue from the measured value for the tested component.
3. Using a multimeter (ohms setting), measure coil re-
sistance between terminals 85 and 86 (Fig. 95). Resist-
ance should be between 70 and 90 ohms.
4. Connectmultimeter (ohms setting)leads to relay ter-
minals 30 and 87. Ground terminal 86 and apply +12
VDCtoterminal85. The relay shouldhave continuity be-
tween terminals 30 and 87 as +12 VDC is applied to ter-
minal 85. The relay should not have continuity between
terminals 30 and 87 as +12 VDC is removed from termi-
nal 85.
5. Disconnect voltage and multimeter leads from the
relay terminals.
6. Connectmultimeter (ohms setting)leads to relay ter-
minals 30 and 87A. Ground terminal 86 and apply +12
VDC to terminal 85. The relay shouldnot havecontinuity
between terminals 30 and 87A as +12 VDC is applied to
terminal 85. The relay should have continuity between
terminals 30 and 87A as +12 VDC is removed from ter-
minal 85.
7. Disconnect voltage and multimeter leads from the
relay terminals.
8. Secure relay to machine and connect machine wire
harness connector to relay.
Figure 95
86
85
87A 87
30
Electrical
System