York DHP30NWB21SDCP30NWB21SDHP36NWB21SDCP36NWB21S Service Manual page 65

High-pressure protection
Use pressure gauge to
no
measure if the pressure is
really high?
yes
no
Check if the operation mode of
indoor unit is set properly?
yes
no
Check if the gas valve and
liquid valve are fully open ?
yes
no
Check if the front panel of
outdoor unit is covered tightly?
yes
no
Check if the air inlet and outlet of
the indoor and outdoor
exchanger is smooth ?
yes
no
Check if the indoor and
outdoor fans operate normally?
yes
no
Check if the indoor swing
louver is fully open ?
yes
no
Check if the capacity output of
outdoor unit is equal to the
capacity demand of indoor units ?
yes
no
Check if the indoor / outdoor
filters or radiating fins are dirty or
blocked ?
no
Clean the fins
yes
Measure if the pressure switch
is normal
no
Set the correct operation
mode
Fully open the valve
Cover up the front panel
properly
Remove the obstructions
Measure the fan motor and
signal input
Measure the swing motor and
signal input
Refer to the dial -up of indoor
and outdoor unit
The system pipe is blocked
Replace the mainboard of
outdoor unit
Replace the pressure switch
Replace the blocked parts or
pipe
58