5284792-UIM-A-0317
Johnson Controls Unitary Products
19
PRESSURE SWITCH FAULT & LOCKOUT
HIGH PRESSURE SWITCH (HPS) FAULT
If the compressor is operating and the high pressure switch is recog-
nized as open, the control de-energizes the compressor output. The 5
minute ASCD timer starts when the compressor speed reaches 0. The
compressor contactor remains off until the high pressure switch has re-
closed and the 5 minute ASCD timer has been satisfied.
HIGH PRESSURE SWITCH LOCKOUT
If the system recognizes two HPS faults within six hours of accumulated
compressor run-time, the system will enter the HPS lockout. During the
lockout period, the defrost and compressor relays remain de-energized.
While the system is locked out, the Outdoor Display will represent the
appropriate fault message as described elsewhere in this document.
The system will differentiate between PS faults that occur in heating or
defrost modes. This is only for the system to decide which fault code to
display. This may help the service person in troubleshooting issues with
the unit when this lockout occurs. Otherwise it shouldn't differentiate
between heating or defrost modes when counting PS faults.
The six hour timing starts after the ASCD has expired following the first
PS fault. The timer only accumulates when the compressor is running.
If the system recognizes a second opening of the PS before the six
hour timer expires, the system will enter the PS soft lockout. If the sys-
tem does not recognize a second opening of the PS before the six hour
timer expires, the six hour timer is cleared and the PS fault counter is
reset.
SUCTION PRESSURE SENSOR FAULT
The system will monitor the suction pressure during operation. If the
suction pressure value falls below the trending limit point and is not
increasing, the low suction pressure fault is recognized. The suction
pressure must remain below the trending limit for 180 seconds in cool
operation. The low suction pressure fault is bypassed for 120 seconds
upon system startup. If the fault limit value is ever reached for > 5 sec-
onds a low suction pressure fault is recognized regardless of a bypass
time.
SECTION IX: INSTRUCTING THE OWNER
Assist the owner with registering the unit warranty using the warranty
card included with the unit, or preferably online at
www.upgproductregistration.com
. It is strongly recommended to com-
plete a startup sheet showing the critical readings of the unit at the time
of commissioning, which can be uploaded as part of the online registra-
tion process.
When applicable, instruct the owner that the compressor is equipped
with a crankcase heater to prevent the migration of refrigerant to the
compressor during the OFF cycle. The heater is energized only when
the unit is not running. If the main switch is disconnected for long peri-
ods of shut down, do not attempt to start the unit until 2 hours after the
switch has been connected. This will allow sufficient time for all liquid
refrigerant to be driven out of the compressor.
The installer should also instruct the owner on proper operation and
maintenance of all other system components.
MAINTENANCE
1. Dirt should not be allowed to accumulate on the outdoor coils or
other parts in the air circuit. Clean as often as necessary to keep the
unit clean. Use a brush, vacuum cleaner attachment, or other suit-
able means.
2. The outdoor fan motor bearings are permanently lubricated and do
not require periodic oiling.
3. If the coil needs to be cleaned, it should be washed with water or a
PH neutral detergent. Allow solution to remain on coil for several
minutes before rinsing with clean water. Solution should not be per-
mitted to come in contact with painted surfaces.
4. Refer to the furnace or air handler instructions for filter and blower
motor maintenance.
5. The indoor coil and drain pan should be inspected and cleaned reg-
ularly to prevent odors and assure proper drainage.
COOLING CHARGE TABLE IS ON THE INSIDE OF THE CONTROL
BOX COVER.
TABLE 10:
Sensor Connector Pin Definition
A1
High Pressure Signal
A2
3.3VDC
TABLE 11:
Low Suction Pressure Limits
Mode of Operation
Trending Limit
Fault Limit
Cool
< 90psi
< 5psi
$
$
$
CAUTION
It is unlawful to knowingly vent, release or discharge refrigerant into
the open air during repair, service, maintenance or the final disposal
of this unit.
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