Electrical Test - Compressor Clutch - New Holland T8010 Manual

Electrical Test – Compressor Clutch
NOTE: See Electrical Schematic sections 58, 60 and 61.
Background
The compressor clutch is cycled On or Off by the
controller based on the temperature sensed at the
evaporator.
When functioning normally, the clutch is always
grounded to the chassis through ring terminal 199F
at the compressor mounting bolt.
The blower speed switch must be in any position but
OFF to engage the compressor.
The controller grounds the compressor clutch relay to
provide 12V from fuse 49 via the blower switch to
energize the clutch coil and engage the compressor.
Power and Ground Circuit
Switched 12V is fed to the compressor clutch relay
on pins 3 and 2 through the blower switch from fuse
49.
The controller energizes the relay by supplying
switched ground from pin A on CCU2 to pin 1 on the
relay.
12V is fed from pin 5 on the relay – through C139-C,
C10-84, and C333-15 – to energize the clutch coil at
C72-A.
Possible Failure Modes:
1. Short circuit or open circuit in clutch coil.
2. Open circuit in power and ground between clutch
and relay.
3. Defective relay.
4. Controller fault.
Section 50 - Climate Control - Chapter 1
50-1-70
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RI03B037