NO
Use a clamp on
amp probe
Is ~20 amps
measured on
T3 or T4?
All Heat relays are
working
YES
Disconnect all power
sources from air handler
Using ohm meter, place
leads across “one-shot”
thermal switch (NTCO).
Are zero ohms
measured across
the NTCO?
NO
NTCO is good.
YES
Is 230VAC
measured from
T1 to T2?
Is ~20 amps
measured on
T1 or T2?
NO
Is heating element(s)
resistance between 11-
13 ohms? See element
layout.
Element is good. Check
all wiring connections
YES
Element is open.
Replace heater
assembly
NO
Heating Element Layout
NOTE: Turn thermostat to Emergency
Heat and raise set-point at least 5
degrees above actual room temperature.
Verify thermostat wiring and setup.
Indoor blower must be energized with
an electric heat call. See field wiring
diagrams in air handler Installer Guide.
Faulty EHC. Replace
and verify operation
NTCO is open. Replace and
verify proper airflow and
blower operation
Is 230VAC
measured from
T3 to T4?
YES
YES
NO
NO
Is 24VAC measured
from W1 – B and W2 – B
at the LVTB?
YES
Troubleshooting Communicating EHC
Fault Code #2 - Heat Relay Stuck Open
YES
NO
Reset Fault history
and check operation
To Next Page
Loading...
