Sequence of Operation
The following Sequence of Operation
applies to PTAC/PTHP units.
The
R_ _C
units are straight cool, single stage air conditioners avail-
able with electric or hydronic heat.
The
R_ _H
units are limited range, single stage heat pump. Mechani-
cal compression heating (heat pump mode) is locked out at outdoor
temperatures of approximately 35 ºF (1.7 ºC) and below. Below
these ambient temperatures, the auxiliary electric or hydronic heat
will be used.
General
The unit is controlled by a microprocessor. Thermostat and control
connections are made to the control board.
- Control Board
Figure 7
Two configuration jumpers are located on the board, see Figure
8. The Heat Pump Configuration Jumper is a 3 pin jumper.
Straight
•
Cool
units R_ _C, the jumper should be located on the
outside two pins.
Heat
•
Pump units R_ _H, the jumper should be located on the
inside two pins.
A second configuration jumper “TEST” allows for the control’s inter-
nal timers to be by-passed for test purposes. Placing the jumper on
the two pins enables the test mode.
A status LED (Light Emitting Diode), LED1 is located on the center
of the board. A series of blinks communicates the status of the board.
Between the blink sequence is a separation of approximately 2 seconds.
The Status Code is listed below.
Trouble
Code
(Blinks)
Status
1
Normal Operation
2
Anti-Short Cycle Timer Active
3
Outdoor Coil Freeze Protection
4
Indoor Coil Freeze Protection
5
Simultaneous “Y” and “W” Call
Initial Power-Up or Power Restoration
When power is applied to the unit, either for the first time or after a
power failure, the board will initialize itself. During the initialization,
LED1 will be lit continuously for approximately 5 seconds. Following
the initialization, a random start timer is initiated. This timer adds
a randomly selected 5-120 seconds to the start-up sequence, reduc-
ing the possibility of multiple units starting at the same time. Once
the random start timer has expired, a 180 second Anti-Short Cycle
Timer is initiated and the Processor Board Trouble Code LED is set
to blink a 2 flash code. This timer prevents the compressor from rapid
cycling. After the Anti-Short Cycle Timer expires, the Processor Board
Trouble Code LED is set to blink a 1 blink Trouble Code, indicating
normal operation.
R_ _C / R_ _H; Cooling Operation
( For unit mount controls)
With the System Switch [SS] set to “Cool”, and the Fan Cycle Switch
[FCS] set to “On” (Continuous Fan Operation), the indoor fan mo-
tor will start. If the Fan Cycle Switch [FCS] is set to “Off” (Cycling
Fan Operation), the indoor fan motor will start with a call for cool-
ing from the internal thermostat [T’stat]. If the unit is equipped
with a Motorized Fresh Air Damper, and is active with the Fresh
Air Switch [FAS], the damper will open with a call for the indoor
fan. If the room temperature is below the thermostat setting the fan
operation will continue as noted above. If the room temperature is
above the thermostat setting, the reversing valve will be energized,
the compressor and outdoor fan will start provided the Anti-Short
Cycle Timer has timed out from the initial power-up, power restora-
tion or a previous compressor on cycle. Operation will continue
until the room temperature satisfies the thermostat. Once the room
temperature falls below the set point by 3 ºF (2 ºC), the compressor,
outdoor fan motor and reversing valve will de-energize. If the FCS
is set to “Off”, the indoor fan will continue to operate for 60 seconds
after the compressor stops. If the FCS is set to “On”, the indoor fan
will continue to operate. As soon as the compressor is de-energized,
the Anti-Short Cycle Timer will be initialized and will prevent the
compressor from starting again for another 180 seconds. While the
Anti-Short Cycle Timer is active, the Processor Board Trouble Code
LED is set to blink a 2 flash code. After the Anti-Short Cycle Timer
expires, the Processor Board Trouble Code LED is set to blink a 1
blink Trouble Code, indicating normal operation.
LED
Indicator
Light
TEST
Config.
Jumper
Heat
Pump
Config.
Jumper
Replacement Packaged Terminal Air-Conditioning / Heat Pump
• Installation, Operation, and Maintenance Manual •
P/N 240008639, Rev. B [8/16/2011]
13
Made in USA
