2900 Selma Highway, Montgomery AL 36108 USA
PH: +1.334.386.5400 (option 2) FAX: +1.334.386.5450 WEB: www.hartzell.aero
Page | 43
MM10001
Dated 1/1/08
Rev L dated 5/21/15
DIAGNOSTIC CHART
Red lamp on
Green lamp on
System is on and calling for heat
Red lamp off
Green lamp on
System is on but not calling for heat
Red lamp blinking
Green lamp on
System is on but ground fault has occurred between switch and solenoid.
Green lamp on,
But no heat output
-no ignition to spark plug
-solenoid stuck in closed position (replace solenoid)
-break in wire between switch and solenoid (repair break)
Green lamp on,
-switch has failed and is supplying voltage to blue wire (replace switch)
-solenoid is stuck in open position (replace solenoid)
Green lamp off
But main power is on
-duct switch not supplying voltage to limit switch red wire
-power to duct switch has been interrupted
-combustion air switch not activated due to low or no airflow or failed
combustion air switch or break in wiring in combustion air circuit
11.4.6 Fuel solenoid
To check the fuel solenoid for proper operation, complete the following:
Separate the fuel solenoid valve, located under fuel line connection cover, from
the blue wire coming out of the cycling switch.
Verify proper operation by applying rated voltage to the solenoid wire in a quiet
environment (no noise). Momentarily make contact 2 or 3 times. By listening
to the solenoid you should hear a positive click as it activates and de-activates.
If no action on the part of the solenoid is noted, consider the solenoid bad.
The solenoid should activate near 1 amp for 12 VDC or .5-1 amp at 24 VDC.
11.4.7 Fresh Air Fan
In most applications power can be obtained by removing the ventilation motor power
wire from terminal #6 for terminal strips numbered 1-6 or terminal #5 for heaters with
terminal strips numbered 4-10. This wire will then become hot when the switch is turned
to Fan Only position.
11.4.8 Fuel Shutoff Valve
Check fuel shut-off valve (remote solenoid), located near fuel source and before the fuel
pump if equipped, for proper operation.
11.4.9 Fuel pump
Always ‘T’ in for fuel pressure checks. Read pressure with heater running. Av-gas 7psi
+ .5 PSI, jet fuel 100 PSI + 5-0 PSI.
11.4.10 Motors
If no power to vent motor, yet power to its supply terminal, check for landing gear squat
switch and/or connections. It is not recommended that HET permanent magnet motors be
repaired. Replacement is recommended in the event of failure. Normal operation of a 12
VDC motor will draw 6-8 amps and 3-5 amps for 24 VDC. Life expectancy is 2000 hrs.
minimum under normal operating conditions.
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