York DHP30NWB21SDCP30NWB21SDHP36NWB21SDCP36NWB21S, Service Manual, Page: 28 / 89

21
Technical Information
Service Manual
6.2 Brief Description of Modes and Functions
1. Temperature Parameters
Indoor preset temperature(Tpreset)
Indoor ambient temperature (Tamb.)
2. Basic Functions
After the initial start up of the compressor,there will be a 3 minute delay before the compressor can start back running. I f the
compressor is in operation before de-energization, the compressor will be started with a 3-minute delay. If the compressor has an
abrupt stoppage due to switch from heat to cool mode , the compressor will not be stopped within 6 minutes regardless of changes in
room temperature .
(1) Cooling Mode
①
Working conditions and process of cooling
When Tamb. ≥ Tpreset, the unit will enter cooling operation, in which case the indoor fan, the outdoor fan and the compressor will work
and the indoor fan will run at preset speed.
When Tamb. ≤ Tpreset -3.6°F, the compressor will stop, the outdoor fan will stop with a time
delay of 60s, and the indoor fan will run at
preset speed.
When Tpreset-3.6°F < Tamb.< 1.8°F, the unit will remain at its previous state.
Under this mode, the four-way valve will be de-energized and temperature can be set within a range from 61°F
~86 °F. If the compressor
is shut down due to setpoint being reached , the indoor fan and the swing device will operate at original state.
②
Protection
Anti-indoor coil freeze protection
Under cooling and dehumidifying mode, 6 minutes after the compressor is started:
If Tevap ≤
35.6 °F, the compressor will operate at reduced frequency.
If Tevap ≤ 30.2 °F is detected for durative 3 minutes, the compressor will stop, and after 60 seconds, the outdoor fan will stop;and under
cooling mode, the indoor fan and the swing motor will remain at the original state.
If Tevap. ≥
42.8 °F and the compressor has remained at OFF for at least 3 minutes, the compressor will resume its original operation state.
Total current up and frequency down protection
If I
total
≤ 16A, frequency rise will be allowed; if I
total
≥ 17A, frequency rise will not be allowed; if I
total
≥ 18A, the compressor will run at reduced
frequency; and if I
total
≥ 20A, the compressor will stop and the outdoor fan will stop with a time delay of 60s.
(2) Dehumidifying Mode
①
Working conditions and process of dehumidifying
If Tamb. > 1.8°F, the unit will enter cooling and dehumidifying mode, in which case the compressor and the outdoor fan will
operate and the indoor fan will run at low speed.
If Tpreset -3.6°F
≤ Tamb. ≤ 1.8°F, the compressor remains at its original operation state.
If Tamb.< Tpreset-3.6°F , the compressor will stop, the outdoor fan will stop with a time delay of 60s, and the indoor fan
will operate at low speed.
②
Protection
Protection is the same as that under the cooling mode.
(3) Heating Mode
①
Working conditions and process of heating
If Tamb. ≤ 3.6°F, the unit enters heating mode, in which case the four-way valve, the compressor and the outdoor fan will operate
simultaneously, and the indoor fan will be stopped until the indoor coil is 104 degrees. After the 104 degrees has been reached the indoor
fan will operate to preset speed speed to prevent cold air in heat mode start up . If Tamb. ≥ 9°F, the compressor will stop, the
outdoor fan will stop with a time delay of 60s, and the indoor fan will stop when the indoor coil is below 104 degrees.
If 3.6°F < Tamb. < 9°F, the unit will maintain its original operating status.
Under this mode, the four-way valve is energized and temperature can be set within a range of 61°F
~86 °F. The operatingsymbol,
the heating symbol and preset temperature are revealed on the display.
②
Condition and process of defrost
Tpreset
T3˚F
Compressor
Outdoor fan
Indoor fan
Run
Tamb.
Stop
Stop cooling
Start cooling
Original working state
≥ 6 min. ≥ 3 min. ≥ 6 min.
Set fan speed