New Holland CX720 Repair Manual page 3067

BODY AND STRUCTURE - ENVIRONMENT CONTROL Air-conditioning system
ENVIRONMENT CONTROL Air-conditioning system - Preliminary
test (E.40.C - F.40.A.20)
1. Start the engine and set the throttle at 1500 RPMs.
Run the engine for ten minutes with the air condi-
tioner set at maximum cooling and the blower on high
speed.
2. Check that the A/C mode switch is pushed in, the
temperature control knob is on cold, and the blower
is on full.
3. Check that the air conditioning components are op-
erating, such as:
Compressor clutch engages when the A/C mode
switch is pushed from"OFF" to "ON" position.
Engine cooling fan is operating.
Blower fan is operating at all speeds.
4. Check the compressor drive belt for slippage.
5. Check the cab air filter to ensure it is clean and free
from obstruction to air flow.
6. Check the evaporator fins. Be sure they are not
plugged or excessively dirty causing insufficient air
flow across the evaporator coil.
7. Check the recirculation filter to ensure that it is clean
and free from obstruction to air flow.
8. Check the condenser core to ensure it is clean and
free from obstruction to air flow.
If the compressor clutch engages but cuts out prema-
turely, the system may be either very low on refrig-
erant charge or have a malfunction of the expansion
valve, low-pressure or high pressure switches. Trou-
bleshoot the system by conducting the System Per-
formance Tests described in ENVIRONMENT CON-
TROL Air-conditioning system - Troubleshooting
(E.40.C - G.40.A.10).
NOTE: If the compressor clutch fails to engage by oper-
ating the air conditioning mode switch when the engine
is first started, it may indicate an electrical problem or
a malfunction of the electric drive clutch on the com-
pressor. Review the electrical diagram in ELECTRICAL
POWER SYSTEM - Electrical schematic frame 48 (A.30
- C.20.E.48)for proper diagnosis.
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E.40.C / 39