Economizer Troubleshooting; Heating Troubleshooting; Phase Loss Protection; Thermistor Troubleshooting - Carrier 48PG03-16 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

Economizer Troubleshooting

Use the unit Scrolling Marquee display or a CCN device to view
the economizer status display and the economizer diagnostic
display (see Appendix A) for information on the economizer
operation. Check the current alarms and alarm history for any
economizer alarm codes and correct any causes. (See Table 92.)
Verify any unique control configurations per installed site
requirements or accessories. If alarms conditions are corrected
and cleared, operation of the economizer may be verified by
using the Service Test mode (see Service Test section and Table
86). The following steps specify how to test the economizer using
the Scrolling Marquee display. See Table 95 for general
economizer service analysis.
1. Enter the Service Test main menu on the display.
2. Enter TEST and turn ON test mode. A password may be
needed in order to turn ON the Service Test. The default
password is 1111.
3. Return to the main level of Service Test.
4. Enter the INDP submenu and enter an initial value for
ECON. This will drive the economizer damper to the
specified position. Continue to adjust the ECON value to
make sure the economizer opens and closes.
5. Because of a mechanical problem with the economizer, the
actuator might acquire a new degree of rotation
less than 90 degrees. If this occurs, a "T414 Economizer
Damper Actuator Out of Calibration" alert will be
generated. This alert can only occur if the economizer is
using digital communications
→ECON→E.CTL = 1 or 2). The economizer calibration
procedure (Service
reconfigure the actuator to the new fully closed and fully
open positions. To implement the calibration procedure,
change E.CAL from OFF to ON. E.CAL will remain ON
as long as the calibration procedure is being implemented
(as long as 5 minutes). During the calibration procedure
the actuator will close fully and then open fully. After the
calibration is complete, the degree of rotation should be
greater than 90 degrees, causing the T414 alert to clear. If
the T414 alert does not clear, check the economizer
damper for other mechanical problems.
6. Return to Service Test→TEST and turn OFF test mode.
This will cause the unit to return to normal operation.

Heating Troubleshooting

Use the unit Scrolling Marquee display or a CCN device to view
the heating status display and the heating diagnostic display (see
Appendix A) for information on the heating operation. Check the
current alarms and alarm history for any heating alarm codes and
correct any causes. (See Table 92.) Verify any unique control
configurations per installed site requirements or accessories. If
alarms conditions are corrected and cleared, operation of the heat
stages and indoor fan may be verified by using the Service Test
mode. (See Table 86.)
Gas Heat (48PG Units)
See Table 96 for general gas heating service analysis. See Fig. 14
for service analysis of the IGC board logic. Check the status LED
on the IGC board for any flashing alarm codes and correct any
causes. (See Table 97.)
which is
(Configuration
Test→IND.P→E.CAL)
will
Electric Heat (50PG Units)
See Table 98 for electric heating service analysis.

Phase Loss Protection

The phase loss protection option will monitor the three-phase
electrical system to provide phase reversal and phase loss
protection.
Phase Reversal Protection
If the control senses an incorrect phase relationship, the relay
(K1) will be de-energized (opening its contact). If the phase
relationship is correct, the relay will be energized. The control has
a self-bypass function after a pre-set time. If the control
determines that the three phases stay in a correct relationship for
10 consecutive minutes, the relay will stay energized regardless of
the phase sequence of three inputs as long as 24-vac control
voltage is applied. This self-bypass function will be reset if all
three phases are restored in a phase loss event.
Phase Loss Protection
If the reverse rotation board senses any one of the three phase
inputs has no AC voltage, the relay will be deenergized (opening
its contact). This protection is always active as long as 24-vac
control voltage is applied, and is not affected by the self by-pass
function of the phase sequence monitoring function. However, in
the event of phase loss, the relay will be re-energized only if all
three phases are restored and the three phases are in the correct
sequence.
A red LED is provided to indicate the function of the board. See
the table below.
LED STATUS
On Continuously Relay contact closed (normal operation).
Relay contact open (phase loss or phase
Blinking
reversal has occurred) — No power will be
supplied to the control system.
Off 24 vac control power not present (off).

Thermistor Troubleshooting

The electronic control uses thermistors to sense temperatures used
to control operation of the unit. Resistances at various
temperatures are listed in Tables 99 and 100. Thermistor pin
connection points are shown in the Major System Components
section. The general locations of the thermistors are shown the
Major System Components section.
Air Temperatures
Air temperatures are measured with 10 kilo-ohm thermistors.
This includes supply-air temperature (SAT), outdoor-air
temperature (OAT), space temperature sensors (T55, T56, T58),
and return air temperature (RAT).
The supply air temperature (SAT) and outdoor air temperature
(OAT) thermistors use a snap-mount to attach through the unit
sheet metal panels. The snap-mount tabs must be flattened on the
tip end of the sensor to release for removal from the panel. (See
Fig. 18.) To reinstall, make sure the snap-mount tabs extend out.
83
FUNCTION