Carrier XtendFRESH, Operation, Service And Parts Manual

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T-366 5–2
AL10 CO
2
SENSOR FAILURE
Cause:
Triggered anytime the CO
2
sensor reading is outside of the normal operation range, after an initial
signal was detected
.
Component CO
2
Sensor
Troubleshooting Check the voltage at MC5 to the ground pin on TP9. (1 - 4.7 vdc)
Check wiring (refer to schematic), and correct if found mis-wired.
If part is available, remove upper fresh air panel and evaporator motor; re-
place sensor. If no part is available, take no action and service at next PTI.
XtendFRESH will continuously run the scrubber. O
2
level will be controlled
with the opening and closing of the fresh air vents as required.
AL29 LOSS OF ATMOSPHERIC CONTROL
Cause: Triggered whenever the CO
2
level is above its upper limit by 1% for 60 minutes. Or, when the O
2
level is greater than 1% below its setpoint for longer than 30 minutes after the unit has been in
range. The alarm is triggered off when the levels return to within the normal range.
Setup Run Cd43 test mode for troubleshooting the below components. If test mode
times out, you must restart the mode prior to the continuation of testing.
Troubleshooting If components do not energize, check FX1 and FX2 for power (460 VAC).
If fuse is open, check heater continuity (XHT1 to ground). Must be greater
than 1 mega ohm. If less than 1, disconnect the heater at XHT1 and XHT2.
Replace fuse. Unit will control on fresh air solenoids.
Component Solenoid Air Vents.
Troubleshooting Visually inspect to see if the Solenoid Valves are opening air vents. If vents
open, troubleshoot the next component. If vents do not open, continue with
troubleshooting below.
Check FX4 fuse for power (~20 volts dc).
If fuse is open, check wiring and or replace solenoid if part is available.
If no part is available, open manual fresh air vent.
Component XtendFRESH Fan(s) / XtendFRESH Scrubber Motor
Troubleshooting Visually inspect to see if the XtendFRESH Fan(s) are running (air blowing on
left, intake on right), check current draw of motor at the XST1 (~40 to 200
milliamps / contactor load side). Troubleshoot the non-operating component.
If both are running, proceed to next component.
Verify XS contactor is pulling in. If not, check FX6 fuse for power (24 VAC).
If not, check power at controller KB4.
Check FX3 fuse for power (~20 vdc). If no power, replace fuse. If fuse opens
a second time, take no further action. O
2
level will be controlled with the
opening and closing of the fresh air vents.
If part is available, replace either fan or scrubber motor. Fan is replaceable
from the front on a loaded unit; Scrubber motor is not. If no part is available
or accessible, take no action and service at next PTI. O
2
level will be con-
trolled with the opening and closing of the fresh air vents.
Component Heater
Troubleshooting Verify XH contactor is pulling in. If not, check FX6 for power (24 VAC). If
open ohm contactors XHA1 and XSA1 to ground. Replace (12 Amp) con-
tactor. If contactor is pulling, power unit off and check heater resistance
from XH1 to XH2 (450 to 500 ohms). If heater is outside of the range, dis-
connect heater at XHT1 and XHT2 and replace at next PTI. Unit will control
on fresh air solenoids.