Lanair MXD300 User Manual
Page 49
Section 14 - Troubleshooting
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s Install a jumper wire between the two F-F
terminals. Be careful not to touch the T-T
terminals as it may damage the control.
s Push reset button for 2 seconds.
s Turn room thermostat up so that it calls for
heat.
s Disable the air operated fuel valve.
s To activate the oil primary momentarily dis
connect one end of the jumper wire on the
F-F terminals. The burner will attempt to fire.
IMPORTANT remove the jumper wire when
testing is complete, and replace the cad cell
wires. Do not run the heater with the cad cell
wires disconnected.
Disabling the air operated fuel valve.
Note: Most trouble shooting tests will require the air operated fuel valve to be disabled, to
do this:
s Adjust the heater air filter/regulator to -0- PSI.
Install jumper wire
Vacuum Gauge reading hints:
No reading 0-1 HG
s Pump not operating.
s Pump air locked and needs priming. Refer to section 10.
s Vacuum leak:
✓ Pump shaft seal
✓ Pump cover gasket
✓ Suction strainer gaskets
✓ Low fuel level in tank
✓ Pipe connections suction side
✓ Strainer in pump cover
Low to normal reading, 1-6 inches HG.
s Pump operating properly.
s Fuel being used has a low viscosity.
s Fuel oil is being used.
s Fuel is at room temperature (warm).
s High level of gasoline in the fuel (use approved fuels only).
High reading, 7 inches of HG, or more.
s Fuel being used has to high of a viscosity. s Suction line strainer dirty or plugged.
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s Fuel contains gear lubes (use approved fuels only).
Reading fluctuates (jumps).
s Vacuum leaks in the suction side of the piping to the pump.
s Low fuel level in the tank.