Residential Air Conditioners and Heat Pumps Using R-22 and Puron® Refrigerant: Application Guideline and Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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A12260
A12261
Fig. 44 – 2-Stage Control Board
TROUBLESHOOTING
Troubleshooting circuit board
HK38EA016, 022, 023, 026
The Evolution Series outdoor units all use the same control board. A
model plug is used to identify the system type, and set the operating
parameters for airflow, start circuit timing etc. (see
Replacement boards may have a different part number from the original
board. A newer board will always be backward compatible to previous
units if it is superseded at RC. Old boards are not always forward
compatible due to new functions, or software changes made to resolve
field issues.
Systems Communication Failure
If communication with the Evolution control is lost with the User
Interface, the control will flash the appropriate fault code (see
).
Check the wiring to the UI and the indoor and outdoor units.
Model Plug
Each control board contains a model plug. The correct model plug must
be installed for or the system to operate properly (see
).
The model plug is used to identify the type and size of unit to the control.
On 286B models, the model plug is also used to determine the start
sequence timing for each individual model.
On new units, the model and serial numbers are inputted into the board’s
memory at the factory. If a model plug is lost or missing at initial
installation, the unit will operate according to the information inputted at
the factory and the appropriate error code will flash temporarily. An RC
replacement board contains no model and serial information. If the
factory control board fails, the model plug must be transferred from the
original board to the replacement board for the unit to operate.
NOTE:
The model plug takes priority over factory model information
inputted at the factory. If the model plug is removed after initial power
up, the unit will operate according to the last valid model plug installed,
and flash the appropriate fault code temporarily.
Pressure Switch Protection
The outdoor unit is equipped with high and low-pressure switches. If the
control senses the opening of a high or low-pressure switch, it will
respond as follows:
1. De-energize the appropriate compressor contactor.
2. Keep the outdoor fan operating for 15 minutes.
3. Display the appropriate fault code (see
).
4. After a 15 minute delay, if there is a call for cooling or heating and
LPS or HPS is reset, the appropriate compressor contactor is
energized.
5. If LPS or HPS has not closed after a 15 minute delay, the outdoor
fan is turned off. If the open switch closes anytime after the 15
minute delay, then resume operation with a call for cooling or
heating.
6. If LPS or HPS trips 3 consecutive cycles, the unit operation is
locked out for 4 hours.
7. In the event of a high-pressure switch trip or high-pressure lockout,
check the refrigerant charge, outdoor fan operation, and outdoor
coil (in cooling) for airflow restrictions, or indoor airflow in
heating.
8. In the event of a low-pressure switch trip or low-pressure lockout,
check the refrigerant charge and indoor airflow during cooling and
outdoor fan operation and outdoor coil in heating.
Control Fault
If the outdoor unit control board has failed, the control will flash the
appropriate fault code (see
). The control board should be
replaced.
Brown-Out Protection
If the line voltage is less than 187v for at least 4 seconds, the appropriate
compressor contactor and fan relay are de-energized. Compressor and
fan operation are not allowed until voltage is a minimum of 190v. The
control will flash the appropriate fault code (see
).
