Carrier PC 111 Air Conditioner User Manual


 
47
CODE 82: SUPPLY-AIR TEMPERATURE SET POINT
POTENTIOMETER FAILURE — If supply-air set point
potentiometer (P1 — located on display board) fails, control
will use a default value. A failure will cause an error code of
82 to be displayed on display board when display button is
pushed; alarm light will also be energized. A failure is deter-
mined by establishing a range of –22 F to 70 F as a valid range.
Anything outside this range will be treated as a failure. If set-
ting is outside the –22 F to 70 F range, alarm light will be ener-
gized and an error code of 82 will be displayed when display
button is pushed; the control will use a set point of 70 F. If set
point is between –22 F and 45 F, control will use a set point of
45 F and no error code will be indicated. If potentiometer
returns to normal, control will automatically reset.
NOTE: The full range of the potentiometer is not used for the
cooling set point range of 45 F to 70 F. The full scale resistance
of the potentiometer is 10 Kohms.
If a failure occurs, one of the following is a probable cause:
Incorrect Potentiometer Setting
— A potentiometer turned
fully clockwise or counterclockwise is outside the valid range
and will cause a failure.
Faulty Wiring
— If wiring is incorrect between potentiometer
and processor board or display board, a failure will result.
Potentiometer Failure
— If potentiometer is shorted or open, a
failure will result.
CODE 83: ECONOMIZER FEEDBACK POTENTIOME-
TER FAILURE — If potentiometer on economizer motor (P2)
fails, control will use a default value of 0% and economizer
outdoor-air dampers will close. The failure will energize alarm
light and cause an error code of 83 to be displayed when dis-
play button is pushed. This potentiometer is a 5 to 15 Kohm
potentiometer. If potentiometer returns to normal, control will
automatically reset. If a failure occurs, one of the following is
the probable cause.
Faulty Wiring
— If the wiring between processor board and
potentiometer is wrong, this will cause a failure.
Potentiometer Failure
— If potentiometer is shorted or open,
this will cause a failure.
Economizer Damper Stuck
— The control has been pro-
grammed to indicate an error if potentiometer travel is less than
10% of the full range. This would happen if dampers or damp-
er linkage were hung up and could not move properly.
CODE 84: RESET LIMIT POTENTIOMETER FAILURE —
This code is applicable only if reset is being used. If reset is
being used, DIP switch 2 must be in the ON position. This
potentiometer (P3) is located on the accessory board. If poten-
tiometer setting is less than 0° F or greater than 80 F, alarm
light will be energized, a diagnostic code of 84 will be dis-
played if display button is pushed, and reset will be terminated.
The full-scale resistance of potentiometer is 10 Kohms, but
when installed on the accessory board in parallel with the other
2 potentiometers, measured resistance will be 3.3 Kohms. This
failure will automatically reset once potentiometer returns to
normal. If a failure occurs, one of the following is the probable
cause:
DIP Switch Problem
— DIP switch 2 is in the ON position
and the accessory board is not installed (accessory board is
standard on these units so it should always be on the unit).
Incorrect Potentiometer Setting
— A potentiometer turned
fully clockwise or counterclockwise is outside the valid range
and will result in a failure.
Faulty Wiring
— If the wiring between the potentiometer and
the processor board is incorrect, a failure will result.
Potentiometer Failure
— If potentiometer is shorted or open, a
failure will occur.
CODE 85: DEMAND LIMIT POTENTIOMETER (P4)
FAILURE — Used only if demand limit is being used. If
demand limit is used, DIP switch 5 must be in the ON position.
Two types of demand limit are available: a field-supplied
and installed single-step control consisting of a 10 Kohm,
3-wire linear potentiometer and an accessory 2-step control.
The single-step control has a single potentiometer while 2-step
control has 2 potentiometers (mounted on the demand limit
board, see Fig. 28).
For both types of demand limit, the control uses only 80%
of the total potentiometer resistance. If resistance of potentiom-
eter is less than 10% or greater than 90%, alarm light will be
energized, a diagnostic code of 85 will be displayed when the
display button is pushed, and demand limit will be terminated.
If a failure occurs, it is probably due to one of the following:
Potentiometer Failure
— If a potentiometer is shorted or open,
a failure will occur.
Incorrect Potentiometer Setting
— A potentiometer turned
fully clockwise or counterclockwise will put potentiometer out
of range resulting in an error.
Faulty Wiring
— If wiring between the potentiometer and the
processor board is incorrect, an error will occur.
DIP Switch 5
— If DIP switch 5 is in the ON position and po-
tentiometer is not installed, an error will occur.
CODE 86: MINIMUM POSITION ECONOMIZER POTEN-
TIOMETER FAILURE — If potentiometer P5 (on accessory
board) setting is less than 0% or greater than 100%, alarm light
will be energized, a code of 86 will be displayed when display
button is pushed and economizer outdoor air dampers will
move to the fully closed position.
The potentiometer full-scale resistance is 10 Kohm, but
when installed in parallel with the other 2 potentiometers on
the accessory board, measured resistance will be 3.3 Kohm.
This failure will automatically reset when potentiometer re-
turns to normal.
If a failure occurs, one of the following is the probable
cause:
DIP Switch 3
— If this switch is in the ON position and the
accessory board is not installed (accessory board is standard on
these units, so it should always be on the unit).
Incorrect Potentiometer Setting
— If potentiometer is turned
fully clockwise or counterclockwise, potentiometer will be out
of the allowable range, and an error will result.
Faulty Wiring
— If wiring between the potentiometer and the
processor board is incorrect, an error will occur.
Potentiometer Failure
— If potentiometer is shorted or open,
potentiometer will be out of range and an error will result.
CODE 87: WARM-UP TEMPERATURE SET POINT FAIL-
URE — Applicable only if morning warm-up is used. Whether
or not unit is equipped with electric resistance heaters, use of
the morning warm-up function is recommended if the unit is
shut down at night or over weekends. In this application, cool-
ing will remain off and the outdoor-air damper will stay closed
until heat load from the occupied space elevates return-air tem-
perature to the warm-up set point. If warm-up function is used,
DIP switch 4 must be in the ON position. The potentiometer
(P6) is located on the accessory board. If potentiometer is set at
less than 0° F or more than 95 F, alarm light will be energized,
a diagnostic code of 87 will appear on the display when dis-
play button is pushed, and control will use a default value of
40 F. If setting is between 0° F and 40 F, control will use a
value of 40 F but no diagnostic code will be displayed; if set-
ting is between 80 F and 95 F, control will use a value of 80 F
but no diagnostic code will be displayed.
The potentiometer full-scale resistance is 10 Kohm, but
when wired in parallel with other potentiometers on the acces-
sory board, measured resistance is 3.3 Kohm.