York DHP30NWB21SDCP30NWB21SDHP36NWB21SDCP36NWB21S Service Manual page 29

Service Manual
When duration of successive heating operation is more than 45 minutes, or accumulated heating time more than 90 minutes, and one of
the following conditions is reached, the unit will enter the defrost mode after 3 minutes.
a. Toutdoor amb. ≥ 41°F, Toutdoor pipe ≤ 28.4°F; b. 28.4°F ≤ Toutdoor amb.
c. 23.4°F < Toutdoor amb. ≤ 28.4°F, Toutdoor pipe ≤ 17.6°F;
d. 14°F < Toutdoor amb. < 23°F, Toutdoor pipe- Tcompensation ≤ Toutdoor amb.-5.4°F;
e. Toutdoor amb. < 14°F, Toutdoor pipe- Tcompensation ≤ Toutdoor amb.-5.4°F;
After energization, when defrosting for the first time Tcompensation=0°F. If it is not the first time for defrosting, the Tcompensation is
determined by the Toutdoor pipe of last time quitting defrosting.
a. Toutdoor pipe > 35.6°F, Tcompensation=0°F; b. Toutdoor pipe ≤ 35.6°F, Tcompensation=5.4°F.
At that time, the indoor fan stops and the compressor stops, and after 60 seconds the outer fan will stop, and then after 30 seconds, the
four-way valve will stop. After 30 seconds, the compressor is initiated for raising the frequency to defrost frequency.
When the compressor has operated under defrost mode for 10 minutes, or Touter tube ≥ 50°F, the compressor will be converted to 46Hz
operation. After 30 seconds, the compressor will stop. And after another 30 seconds, the four-way valve will be opened, and after 60
seconds, the compressor and the outer fan will be started, the indoor fan will run under preset cold air prevention conditions, and H1 will be
displayed at temperature display area on the display panel. Defrost frequency is 70 Hz.
3.Protection
Cold air prevention
The unit is started under heating mode (the compressor is ON):
① In the case of Tindoor amb. < 75°F: if T tube ≤ 104°F and the indoor fan is at stop state, the indoor fan will begin to run at low speed with a
time delay of 2 minutes. Within 2 minutes, if T tube > 104°F, the indoor fan also will run at low speed; and after 1 minute operation at low
speed, the indoor fan will be converted to operation at preset speed. Within 1 minute low speed operation or 2 minute non-operation, if T
tube > 108°F, the fan will run at present speed.
② In the case of Tindoor amb. < 75°F: if Ttube ≤ 108°F, the indoor fan will run at low speed, and after one minute, the indoor fan will
be converted to preset speed. Within 1 minute low speed operation, if Ttube > 104°F, the indoor fan will be converted to preset speed. Note:
Tindoor amb. indicated in ① and ② refers to, under initial heating mode, the indoor ambient temperature before the command to start the
compressor is performed according to the program, or after the unit is withdrawn from defrost, the indoor ambient temperature before the
defrost symbol is cleared.
Total current up and frequency down protection
If the total current I ≤ 16A, frequency rise will be allowed; if I ≥ 17A,frequency rise will not be allowed; if Itotal18A, the compressor will
total total
run at reduced frequency; and if Itotal20A, the compressor will stop and the outdoor fan will stop with a time delay of 60s.
(4) Fan Mode
Under the mode, the indoor fan will run at preset speed and the compressor, the outdoor fan, and the four-way valve will de-energize.
Under the mode, temperature can be set within a range of 61°F~86°F.
(5) AUTO Mode
① Working conditions and process of AUTO mode
Under AUTO mode, standard cooling temperature Tpreset is 77°F and standard heating temperature Tpreset is 68°F.
a. Once energized, if Tamb. ≤ 71.6°F, the unit will be started under heating mode; if 71.6°F < Tamb.< 78.8°F, the unit will run under fan mode
and the run indicator will be bright; and if Tamb. ≥ 78.8°F, the unit will be started under cooling mode.
b.Under AUTO mode,if Tamb. ≥ Tpreset +1.8ºF is detected,the unit will select to run under cooling mode,in which case implicit
presettemperature is 77°F; if Tamb. ≤ Tpreset-1.8°F, the compressor will stop, the outdoor fan will stop with a time delay of 1 minute,
and the indoor fan will run at preset speed; and if Tpreset-1.8°F < Tamb. < Tpreset+1.8ºF, the unit will remain at its original state.
c.Under AUTO mode, if Tamb. ≤ Tpreset+3.6°F is detected, the unit will select to run under heating mode, in which case implicit preset
temperature is 64°F; if Tamb. ≥ Tpreset+9°F, the compressor will stop, the outdoor fan will stop with a time delay of 1 minute,and the indoor
fan will run under the mode of residue heat blowing; and if Tpreset+3.6°F < Tamb.< Tpreset+41°F, the unit will remain at its original state.
The cooling-only unit will run under fan mode.
d.Under AUTO mode, if 71.6°F < Tamb.< 78.8°F, the unit will remain at its original state.
② Protection
a. In cooling operation, protection is the same as that under the cooling mode.
b. In heating operation, protection is the same as that under the heating mode.
(6) Common Protection Functions and Fault Display under COOL, HEAT, DRY and AUTO Modes
① Overload protection
Ttube: Measured temperature of outdoor heat exchanger under cooling mode; and measured temperature of indoor heat ex-changer
under heating mode.
1) Cooling overloada.
a. If Ttube ≤ 126°F, the unit will return to its original operation state.
b. If Ttube ≥ 131°F, frequency rise is not allowed.
Technical Information
22