Farm Fans C-2120A Operator's Manual page 64

TROUBLE
Burner fires - but
operates only about
one minute and dryer
shuts down
Burner will not fire -
but gauge shows gas
pressure
Burner operates but
will not cycle from Lo-
Fire to Hi-Fire
Burner operates but
will not cycle from Hi-
Fire to Lo-Fire
Burner maintains
desired drying temper-
ature, but cycles from
Hi-Fire to OFF (with-
out going into Lo-Fire)
CHECKOUT PROCEDURE & INFORMATION
1. Wait for several minutes for lock-out device to cool down, then restart the dryer. Immediately after
the burner starts operating, connect voltmeter leads across Burner Control Circuit terminal nos. 2
and T and continue to observe the meter. When burner first comes ON (with a cold flame switch),
the voltmeter should indicate 230 volts. After the flame switch becomes HOT and opens its con-
tacts, the meter should read ZERO. After the burner fires, the flame switch should OPEN within
approximately 15 seconds or less.
If burner shuts down without the meter indicating that the contact points have opened, it indicates
either a defective flame switch or insufficient heat exposure on the flame switch.
1. IGNITION TRANSFORMER - Check transformer for spark by removing ignition wire from trans-
former and holding an insulated handle screwdriver against the output terminal and 1/4" away from
the case. There should be a strong spark. Check transformer wiring and connections. Replace
the ignition transformer, if required. Make sure transformer case is properly grounded to heater
housing.
2. IGNITOR PLUG - Check that ignitor plug is properly gapped to 3/32 inch and has a strong spark.
Inspect ignition wire and its connections. Make sure wire is not shorted or broken. Check ignitor
plug for damaged electrodes or cracked insulator. Replace, or clean and service ignitor plug, as
required.
3. FUEL SUPPLY - Inspect burner venturi and orifice for possible obstructions. Clean parts as
required.
1. Check for an excessive Lo-Fire gas adjustment setting. Observe pressure shown on gauge and
compare reading with recommended flow control valve pressure setting listed in manual. Readjust
Lo-Fire setting on flow control valve, if required.
2. Check for improperly adjusted or problems within Hi-Lo Fire thermostat control (plenum controller)
circuit. Temporarily increase the temperature setting. If heater will still not cycle, check for problem
in control wires connections or sensor. See Electronic Temperature Control Trouble in this
Troubleshooting Section.
3. Check for improperly connected or faulty Hi-Fire gas vapor solenoid valve. Correct any poor con-
nections or defective wiring. If wiring appears proper, problem may be caused by a burned-out
valve coil or defective valve. Replace Hi-Fire solenoid valve, or its coil, if defective.
1. Check gas pressure reading on gauge. Problem may be due to insufficient gas regulator setting.
Temporarily decrease the thermostat setting to verify that thermostat will function and cause the
burner to cycle. If burner will cycle at reduced thermostat setting, it indicates that problem was
due to insufficient heat to satisfy the original thermostat setting. Reset thermostat to original set-
ting and increase gas regulator setting for additional heat output. Do not exceed the maximum
pressure listed for Operating Pressure Range in Fig. 2-3.
2. Hi-Lo Fire thermostat control may be defective. If burner still will not cycle to Lo-Fire after
decreasing the thermostat, the problem may be due to a failed sensor. See Electronic
Temperature Control Trouble in this Troubleshooting Section. Observe reading on thermometer.
Replace control assembly if it cannot be set to cause its switch to go to the open circuit position
with normally hot air plenum temperatures.
3. If burner continues to operate on Hi-Fire, check the Hi-Fire gas solenoid valve for a stuck or
blocked open condition, or for reversed gas pipe connections. THE SOLENOID VALVE MUST
NOT ALLOW GAS FLOW WHEN ITS COIL IS NOT ENERGIZED.
1. Make sure the flow control valve is not set completely closed. Valve must be adjusted open to pro-
vide the proper Lo-Fire gas pressure listed in manual.
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