Carrier R-22 Application Manual And Service Manual page 21

Table 11—Defrost Control Speed-Up Timing Sequence for CES0110063/CES0130024
PARAMETER
30-minute cycle
50-minute cycle
90-minute cycle
10-minute cycle
5 minutes
12. After a few minutes in defrost (cooling) operation, liquid line
should be warm enough to have caused defrost-thermostat
contacts to open. Check resistance across defrost thermostat.
Ohmmeter should read infinite resistance, indicating defrost
thermostat has opened at approximately 80°F.
13. Shut off unit power and reconnect fan lead.
14. Remove jumper between DFT and R terminals. Reconnect
defrost-thermostat leads. Failure to remove jumper causes unit
to switch to defrost every 30, 50, or 90 minutes and remain in
defrost for full 10 minutes.
15. Replace control-box cover. Restore power to unit.
If defrost thermostat does not check out following above items or
incorrect calibration is suspected, check for a defective thermostat
as follows.
1. Follow items 1-5 above.
2. Route sensor or probe underneath coil (or other convenient
location) using thermocouple temperature-measuring device.
Attach to liquid line near defrost thermostat. Insulate for more
accurate reading.
3. Turn on power to outdoor unit.
4. Restart unit in heating.
5. Within a few minutes, liquid-line temperature drops within a
range causing defrost-thermostat contacts to close. Tempera-
ture range is from 33°F to 27°F. Notice temperature at which
ohmmeter reading goes from
contacts close at this point.
6. Short between the speed-up terminals using a small, slotted
screwdriver.
7. Unit changes over to defrost within 21 sec (depending on
timing-cycle setting). Liquid-line temperature rises to range
where defrost-thermostat contacts open. Temperature range is
from 75°F to 85°F. Resistance goes from zero to
contacts open.
8. If either opening or closing temperature does not fall within
above ranges or thermostat sticks in 1 position, replace
thermostat to ensure proper defrost operation.
CES0130024 DEFROST CONTROL
Some heat pumps built in 1993 and later incorporated a new
defrost control similar to the CES0110063 except the 5-minute
cycle protector has been removed. This control is used on heat
pump units with reciprocating compressors where short-cycle
protection is not required.
Troubleshooting this control will be the same as the CES0110063
control except for the cycle-protector function. The CES0130024
control is identical to the CES0110063 except the T2 terminal and
cycle-protector logic have been removed.
CES0130076 DEFROST CONTROL
This defrost control is the same size as the CES0130063 control
but is not backwards-compatible. (See Fig. 22.) To upgrade to the
MINIMUM
27
45
81
9
4.5
to zero ohms. Thermostat
when
MAXIMUM
33
55
99
11
5.5
new control, you must have replacement-defrost thermostat and
harness kit. See your replacement-component representative for kit
part number.
Defrost Settings
The defrost control is a time/temperature control which includes a
field-selectable time period (DIP switch 1 and 2 on board, see
Table 12) between defrost cycles of 30, 60, 90, and 120 minutes
(factory-set at 90 minutes).
Table 12—Defrost Timer Settings
SW1
On
Off
Off
On
To initiate a forced defrost, two options are available, depending
on the status of the defrost thermostat.
If defrost thermostat is closed, speedup pins (J1) must be shorted
by placing a Flathead screwdriver in between for 5 seconds and
releasing, to observe a complete defrost cycle. When the Quiet
Shift switch is selected, compressor will be turned off for two,
30–second intervals during this complete defrost cycle. When
Quiet Shift switch is in factory-default OFF position, a normal and
complete defrost cycle will be observed.
If defrost thermostat is in open position and speedup pins are
shorted (with a Flathead screwdriver) for 5 seconds and released,
a short defrost cycle will be observed (actual length is dependent
upon the selected Quiet Shift position). When Quiet Shift switch is
in ON position, the length of defrost is 1 minute (30 seconds
compressor-off period followed by 30 seconds of defrost with
compressor operation). On return to heat operation, compressor
will again turn off for an additional 30 seconds and the fan for 40
seconds. When the Quiet Shift is in OFF position, only a brief
30–second cycle will be observed.
If it is desirable to observe a complete defrost in warmer weather,
the thermostat must be closed as follows.
1. Turn off power to outdoor unit.
2. Disconnect outdoor fan-motor lead from OF2 on control board
(See Fig. 22.). Tape to prevent grounding.
3. Restart unit in heating mode, allowing frost to accumulate on
outdoor coil.
4. After a few minutes in heating mode, liquid-line temperature
should drop below closing point of defrost thermostat (ap-
proximately 30° F).
NOTE: Unit will remain in defrost until defrost thermostat
reopens at approximately 80° F coil temperature at liquid line or
remainder of defrost cycle time.
5. Turn off power to outdoor unit and reconnect fan-motor lead
to OF2 on control board after above forced-defrost cycle.
Compressor Shut Down
21
SPEED-UP
(NOMINAL)
7 sec
12 sec
21 sec
2 sec
1 sec
SW2 SW3
Off 30
On 60
Off 90
On 120