14
loss of capacity
• If the system looses capacity (does not maintain the
thermostat temperature setting), either the system is under-
sized, there is a malfunctioning metering device, or there is
a possible refrigerant leak.
notE:
If a leak occurs, head and
suction pressures will be low, ice will likely form on the air
handler refrigerant lines (when the system is in the cooling
mode), and the compressor will become very hot (usually
over 200° F in the heating mode).
• If a leak has occurred, remove all refrigerant, fix the leak,
and re-weigh in the correct originally recorded amount of
virgin refrigerant shown in the charging instructions.
• If the system is under-sized, the problem will typically become
apparent in cooling mode. As more sub-surface heat transfer
tubing area exposure is required in the cooling mode than
in the heating mode. If only modestly under-sized, normal
supply/return temperature differentials will be close, but not
at peak, and pressures will be abnormally high during the
day, but will typically return to close to normal levels by the
morning.
restricted refrigerant system
The following conditions are apparent in the cooling mode of
operation. A restriction may not be evident in both the heating
and the cooling modes of operation.While restrictions may
result from a number of causes, the following are examples
of common restrictions.
• Dirty filter/dryer
• A crimped/damaged refrigerant line.
• A mal-functioning reversing valve or expansion device.
• Debris lodged within an expansion device.
• Clogged oil separator filter
Check for crimped/damaged refrigerant lines and check the
metering device. A partial restriction at the metering device
can result in gurgling sounds, whereas a complete restriction
will result in no sound at all because there is no refrigerant
flow. If there is a restriction at the metering device, frost/icing
may appear on the exterior of the suction line between the
metering device and the compressor.
If there is a complete restriction, the compressor’s amperage
draw may be lower than normal since the compressor is running
in a vacuum with no load. The compressor will eventually
overheat and shut off by its own internal overload, since the
motor’s windings are not being cooled by refrigerant vapor.
sand or Dirt In the sub-surface tubing
(Prior to Initial Charging)
The following steps should be performed if debris removal
is required after the field lines have been connected to the
liquid line assembly:
1. Recover all refrigerant from from the line set to the borehole.
2. Close off the lower two shut-off valves to the borehole at
the end of the liquid line assembly.
3. Cut open the vapor lines outside the compressor section.
4. Install a shutoff valve on the top open end of the vapor line.
notE:
After the valve is installed, make sure it is in the
closed position.
5. Starting with a full large bottle of dry nitrogen, fill the line
set with 500 psig of dry nitrogen, and keep the pressure
regulator open at 500 psig. Keeping a safe clearance from
the end of the vapor line, point the end of the vapor line
away from any object that could be damaged by exiting
debris. Instantly open the shut-off valve on the vapor line,
Figure 4. Example of Event code
b
.
p
.
DIsPlaY
DuratIon
(sEconDs)
InDIcatEs
SL
2
Current Status
..
1
2
Most Recent Event
..
1
2
Next Event
..
1
2
Next Event
..
1
2
Next Event
..
1
2
Oldest Event
..
1
Repeats
In this example, the unit has entered soft lock mode due to excessive hot
gas injection events.
table 8. Example sequence
table 7. status & Event codes
status
coDE
DEscrIPtIon
Unit is running in cooling mode
Unit is running in heating mode
Unit is in standby, waiting for a call to operate
SL
Unit has entered a Soft Lock state due to excessive faults.
EVENT
coDE
DEscrIPtIon
The unit is delaying start because the anti-short cycle timer
has not yet expired
The unit has opened the Hot Gas Injection Valve
The unit did not start due to high discharge pressure
The unit has stopped due to high discharge pressure
The unit did not start due to low suction pressure
The unit has stopped due to low suction pressure
The suction pressure sensor has a fault
The suction temperature sensor has a fault
The discharge pressure sensor has a fault
The unit has stopped due to excessive Hot Gas Injection
Events
The unit ended heating mode early due to high suction
pressure
The unit ended heating mode early due to high discharge
pressure
