24VNA6: Installation Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
15
Outdoor Pressure Transducers
There are two pressure transducers installed on this unit. One is located
at the discharge of the compressor and the other is located at the suction
of the compressor. These are labeled as "P1" and "P2" on the PCM and
the connection to the control board can be interchanged without
impacting the pressure measurements or system control. These
transducers have a range from 0 to 620 psig and are used for system
protection, calculating superheats, and diagnostics.
Crankcase Heater Operation
This unit has a compressor crankcase heater that will be energized to
prevent the compressor from being the coldest part of the system thus
enhancing the reliability. The indoor unit and UI do not need to be
installed for the crankcase heater to operate properly.
Infinity Controlled low ambient cooling
This unit is capable of low ambient cooling down to 0F (-17.8C) with
Low Ambient enabled on the Infinity Control. A low ambient kit is not
required.
The Infinity Control provides an automatic evaporator coil freeze
protection algorithm that eliminates the need for an evaporator freeze
thermostat. The only accessory that may be required is wind baffles in
locations which are likely to experience cross winds in excess of 5 miles
an hour. This generally occurs only on roof and open area applications.
Low ambient cooling must be enabled in the User Interface setup. The
outdoor unit fan will cycle on and off based on outdoor coil temperature,
outdoor air temperature, and suction pressure measurements to keep the
compressor running at the proper conditions.
Troubleshooting
Systems Communication Failure
If communication with the Infinity control is lost with the User Interface
(UI), the control will flash the appropriate fault code (see
).
Check the wiring to the User Interface and the indoor and outdoor units
and power.
Model Plug
Each control board contains a model plug. The correct model plug must
be installed for the system to operate properly (see
).
The model plug is used to identify the type and size of unit to the control.
On new units, the model and serial numbers are input 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 input 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
input 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 pressure switch. If this switch
opens the VFD will lose line power and the compressor and fan motor
will not operate. The high pressure switch opens at 670 +/- 10 psig and
closes at 470 +/- 25 psig. If this occurs the PCM will set a diagnostic
code per table 7. The outdoor pressure transducer installed at the
discharge of the compressor is monitored by the PCM and the PCM will
take action to avoid the high pressure switch from opening.
Compressor Protection
The Primary Control Module continuously monitors the operation of the
compressor and takes action when it is nearing the edge of the
boundaries of reliable operation. The PCM utilizes the pressure
transducers to maximize the reliability and minimize the off time of the
system due to operation outside of the compressor boundaries. The
PCM takes different actions for each edge of the boundary, but each
culminates in a reduction of compressor speed to the minimum
allowable and, in the worst case, will power off the compressor to avoid
excursions outside the boundaries. If a shutdown does occur then the
PCM will set a diagnostic code per
.
Line Voltage Diagnostics
The primary control module monitors the line voltage for low and high
voltage events. If a low voltage or high voltage event occurs and another
fault occurs simultaneously the PCM will set a fault that indicates this
was due to the system conditions and not the components. If this occurs
several times in a row the PCM will set a malfunction and lock out
operation for 1-4 hours, depending on the condition. Refer to
for
the list of fault codes and
for the list of malfunctions and the
lockout times for each one.
Forced Defrost Pins (J9)
The forced defrost pins have several functions. When shorting the pins
using a clip wire the below functions can be executed:
• If the pins are shorted more than 1 second and less than 5 seconds
when the system has just turned off and an active call for cooling is
present, the 5 minute initial on-time will be defeated.
• If the unit is in the OFF mode and the pins are shorted at power on the
unit will enter into Status Code Recall Mode.
Temperature Thermistors
Thermistors are electronic devices which sense temperature. As the
temperature increases, the resistance decreases. Thermistors are used to
sense outdoor air (OAT), coil temperature (OCT), and the outdoor
discharge thermistor (ODT) at the outlet from the compressor.
Refer to
and
for resistance values versus temperature for
the OAT and OCT.
Table 3 – Model Plug Information
MODEL
NUMBER
MODEL PLUG
NUMBER
PIN RESISTANCE
(K-ohms)
Pins 1-4
Pins 2-3
24VNA624
HK70EZ009
5.1
91
24VNA636
HK70EZ021
11
39
24VNA648
HK70EZ033
18
11
24VNA660
HK70EZ045
18
220
CAUTION
!
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage and/or
improper operation.
Do not attempt to install an incorrect model plug as this could cause
some units to operate incorrectly and fail prematurely.
Table 4 – Resistance Values versus Temperature
TEMPERATURE
RESISTANCE (ohms)
25.0°C (77.0°F)
10.0 + / - 2.3%
0.0°C (32.0°F)
32.6 + / - 3.2%
-17.8°C (0 °F)
85.5 + / - 3.4%
