Carrier AirStream 42WKN08-36 Installation, Operation And Maintenance Instructions page 60

PROBLEM
Water Leaking from Unit
(also see Condensate High Level
Section)
No Heating (Hot Water)
No Heating (Electric Heat)
Electric Overheat
LEGEND
LED — Light-Emitting Diode
PCB — Printed Circuit Board
Table 7 — Troubleshooting (cont)
POSSIBLE CAUSE
Condensate plug loose or missing
Unit installed unevenly
Condensate drain piping installed 
incorrectly
Blocked/kinked condensate pipe
Condensate pump blocked or failed
Float switch failure
Incorrect MODE setting
(Microprocessor units only)
Set point too low
Blocked or dirty filters causing low 
airflow
No hot water/pumps failed
Faulty valve/actuator
Faulty heater relay
Incorrect MODE setting
(microprocessor units only)
Set point too low
Overheat cutout tripped
(Also see Electric Overheat section)
Heater element failed
Faulty heater relay
Automatic or manual reset overheat
cutout tripped
60
POSSIBLE SOLUTION
Check that the rubber condensate plug is securely fitted to the
underside of the unit's polystyrene drip tray. On some models
this is located underneath the fascia support rails on the pump
side of the unit.
With fascia removed, ensure that the unit chassis is level (at the
face) both front to back and left to right, to ensure correct
condensate flow.
Check that the site installed condensate gravity drain slopes
'downhill' away from the unit. (See page 42 of this manual for
installation guide.)
Check condensate piping for blocks/kinks, clear as necessary.
Check for a water tight connection between the condensate
outlet and the site installed condensate gravity drain.
Clear any blockages and ensure that power is being applied to
the pump. If the pump still does not run, replace the pump.
Check that the float switch operates correctly and is properly
positioned. Float switch is normally closed, opens on rise of
water level.
Check that the transmitter MODE is set to Heat or Auto Mode.
Check the set point on the transmitter or wall mounted
thermostat and adjust if necessary.
Check condition of filters. (See page 57 for filter removal and
cleaning instructions.)
Check hot water source and supply to unit.
Check actuator by manually opening and closing valve, replace if
faulty.
Check signals to relay and check action of relay contacts.
Replace relay or PCB if necessary.
Check that the transmitter MODE is set to Heat or Auto Mode.
Check the set point on the transmitter or wall-mounted
thermostat and adjust if necessary.
Investigate cause of over heat condition.
Possible low airflow, check filter condition.
(See page 57 for filter removal and cleaning instructions.)
Possible fan failure. Check fans.
(See Fans Will Not Run section.)
Remove power from unit and reset manual overheat cutout by
rubbing. DO NOT PRESS. Consult Factory for instruction if 
necessary.
Investigate and replace if necessary.
Check signals to relay and check action of relay contacts.
Replace relay or PCB if necessary.
The electric heat circuit contains one automatic reset and one
manual reset overheat cutout protection switch for each electric
heat element fitted to the unit. The cutouts are wired in line with
the main power flowing in each element and operate as
described below.
Automatic cutout: If the auto cutout trips, the electric heat is
temporarily disabled until the unit temperature falls and causes
the overheat cutout to automatically reset.
Manual cutout: If the manual cutout trips, the electric heat is
disabled until the unit temperature falls and the overheat cutout is
manually reset. It will typically take five minutes for the unit
temperature to fall sufficiently to allow the cutout to be reset. The
cutout should only be reset by a qualified and competent
electrician and with the main power switched off. Ensure the
elements have cooled sufficiently.