Imperial Home Page -> Repair -> Accessories -> Gas Heater -> Page 9
ture control in high position). The fuel valve will open and spray from nozzle can then be examined.
Have a fire extinguisher at hand and avoid any possibility of igniting the spray. NEVER attempt to burn this assembly in the open.
1. The spray pattern must consist of a fine mist of fuel which is symmetrical in shape and is centered in mixer assembly. There must be no dripping or leakage around nozzle seat. If spray is coarse or uneven, or is directed at an angle in the mixer, the nozzle is defective and must be replaced.
m. Additional causes of burner failure are excessive clogging of screen in fuel inlet, clogging of fuel passages within burner casting, or a defective valve plunger or seat. Check these parts and replace as required.
38. HEATER GETS TOO HOT
This trouble can be caused by a poorly adjusted thermostat or insufficient fresh air. To test thermostat, connect a test light between white terminal of ignition unit and ground. Start heater with engine running. After heater warms up, the test light should go on and off as thermostat cycles the heater on and off. If the heater cycles, but test light remains on, it is an indication that thermostat contacts are remaining closed and heater is cycling on overheat switch. Install a new thermostat to correct this condition. The fresh air supply should be checked before replacing thermostat since proper thermostat action is dependent upon an adequate supply of fresh air through heater system. Insufficient air flow can be caused by defective fresh air blower motor or by an obstruction in fresh air system. Distributive ducts door must be open at any time heater is in use. Door is controlled by temperature lever on instrument panel.
39. HEATER WORKS INTERMITTENTLY
a. If heater gets very hot and shuts itself on and off in an intermittent way, the trouble is probably caused by insufficient fresh air flow. This will cause heater to shut off on the overheat switch. Check fresh air blower and short coupling duct between blower and heater, also distribution duct door where air enters duct on right side of passenger compartment.
b. Another cause of intermittent operation is air lock in heater fuel pump caused by small air bubbles in fuel. To correct this condition, inspect the heater fuel take-off tee in engine fuel pump. If heater fuel line comes off at top, remove fittings from fuel pump and reinstall them so that the heater fuel line is attached at the bottom. This will prevent bubbles from entering fuel pump. Tighten all fittings carefully and bleed fuel line after it is attached to heater fuel pump.
40. HEATER CAUSES ODOR
a. If odor is raw gasoline, the fuel connection at burner casting is leaking or solenoid valve is not tight on casting. Check and tighten leak. A slight odor when a new heater is first turned on should be disregarded.
b. If odor is burned gasoline, the exhaust tube under heater is leaking and must be repaired.
41. TOO MUCH SMOKE FROM HEATER
Excessive smoking and carbon are caused by a slow combustion air motor or a defective nozzle. Check these causes and repair or replace as required. This condition could also be caused by delayed ignition, resulting from spark plug electrodes which are badly burned, out of adjustment, or shorted with carbon. Check plug gap. It should be .085 inches and the electrode should be reasonably clean and approximately centered in insulator of spark plug. Bend the ground electrode when making adjustment.
42. HEATER MAKES NOISE WHEN STARTING
a. If heater "pops" or "spits" when starting or cycling, it is an indication that fuel is being admitted to burner that is not being instantly ignited. This can be caused by a leaking solenoid valve seat or plunger which will permit fuel to flow in the "off" position. Another possible cause is low fuel pressure from a defective pump, or a combination of low fuel pressure and insufficient combustion air caused by a slow burner blower motor.
h. Check fuel pressure first; if pressure is satisfactory, remove entire burner assembly from heater. Disconnect ignition cable and solenoid leads, but reconnect the fuel line. Examine inside of mixer can to make sure the
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