York YUHC 07-18 User Manual

1.  Condition to start defrosting: Units will switch to defrosting 

mode when either of the following conditions is met.

a.  Unit  has  been  running  under T3  <  0ºC  for  40 

minutes and T3 < -3ºC for 3 minutes.

b.  Unit has been running at high temperature protection 

mode*  for  90  minutes.  (*High  temperature 

protection mode: when coil temperature of indoor 

unit reaches 55°C, outdoor unit will turn off external 

unit fan but still keep compressor running).

2.  Condition to stop defrosting: Units will switch back to 

heating mode when either of the following conditions 

is met.

a.  Unit has been running at defrosting mode for 10 

minutes.

b.  T3 > 20

 

ºC

Remark: T3 is coil temperature of outdoor units.

T3 (°C)

3 min

40 min

Heating mode

Defrosting mode

Time 

Elapsed 

(min)

Starting Defrosting Mode under condition a.

The units are designed to operate for long periods of time with a minimum of maintenance. However, the following 

operations must be performed regularly.

Air filter

1 -  Clean  with  a  vacuum  cleaner  or  tap  gently 

then wash in warm water (40°C) with a mild 

detergent.

2 -  Rinse and dry before replacing on unit.

3 -  Never use petrol, alcohol or any other chemi-

cal product.

Every month or more often if

necessary.

Unit casing

1 -  Remove dust from the front panel with a soft 

duster or wipe a damp cloth with a mild soap 

solution.

2 -  Never use petrol, alcohol or any other chemi-

cal product.

Every month or more often if

necessary.

Drain pan and evacu-

ation piping

1 -  Clean and check for obstructions.

Each season before start up.

Indoor / Outdoor coils

1 -  Check  condition  and  remove  dust  from  be-

tween coil fins.

Each season before start up.

Compressor

1 -  No maintenance required.

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