ENVIRO-TEC
47
FORM ET115.24-NOM11 (118)
Insucient
heating
CAUTION:
UNIT MAY BE
EXTREMELY
HOT. TAKE
GREAT
CARE WHEN
TROUBLE-
SHOOTING.
Intermittent demand for heating.
Verify that thermostat or control command signal is not dropping
out. Verify voltage is continuously present at unit during demand
for heat.
Heater is short cycling Verify thermostat settings. Verify proper location of thermostat.
Open or damaged heater elements
With power removed, disconnect heater wire harnesses. (These
are the harnesses with the black plugs.) Use a volt-ohm meter
to measure the resistance across the electric heat power harness
coming out of the heater section. Verify ohms approximately
equal to (Unit Volts)2/Unit kW.
Loss of stage
Loss of demand for second stage. Verify demand voltage at stage
2 contactor.
Incorrect voltage applied. Verify proper voltage to unit per unit label.
Electric heat contactor fault
Verify heating demand voltage is at each electric heat contactor
control coil terminals. If power is present but contactor is not
actuated, replace contactor. To verify contactor: with power
removed, unwire contactor and verify continuity across contacts
when manually operated. Cover of contactor will need to be
removed to access manual operator. Replace contactor if faulty.
Primary limit switch cycling.
Verify no loss of demand to unit. Verify that voltage exists
continuously on heater contactor during demand for heat. If
demand reaches unit but not contactor, primary limit is tripped.
The primary limit switch(es) will auto-reset once the unit cools
down. If unit is hot, wait for heater to cool down. This may take
up to an hour. If limit trips again, verify heater is not overheating.
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