Farm Fans C-2120A Operator's Manual page 63

TROUBLE
Fan motor will not
start
Bottom auger will not
start
Meter rolls will not
operate (SCR drive)
Burner will not fire
with fan operating
(Control circuit mal-
function)
Burner will not fire -
No gas pressure with
fan operating at least
15 seconds (gas sup-
ply or fan-heater
component)
CHECKOUT PROCEDURE & INFORMATION
1. Check that fan circuit breaker and fan switch are ON; also for defective switch or bad wiring connec-
tions.
2. Verify closing of fan motor contactor; check for voltage on load side of contactor and for 120V to
contactor coil. See POWER CIRCUIT and GENERAL CONTROL CIRCUIT wiring diagrams for fan
circuit details. Inspect contactor for defective points or burned-out coil.
3. Inspect connections and check voltage applied to motor leads in fan-heater control box to determine
if motor is defective.
4. If motor starts slowly, check for low voltage during starting, due to excessive voltage drop in power
supply wiring.
1. Check that bottom auger circuit breaker is ON.
2. Check that UNLOAD switch is set to AUTO.
3. Verify closing of bottom auger contactor; check voltage on load side of contactor, power terminals
13, 14, and 15.
4. If power was present in previous step, inspect connections and check voltage applied to motor leads
in junction box to determine if motor is defective.
1. Check that UNLOAD circuit breaker is ON, SCR SPEED CONTROL is properly set, UNLOAD switch
is on AUTO and that meter rolls are not jammed (with SCR motor stalled or drive belt slipping).
2. Check that 230V is present across the load side of the special 10 Amp rectifier fuses (terminal nos.
60 and 62). Replace fuses if blown and determine cause (short circuit or severe voltage spikes,
etc.).
3. Check that the unload contactor is energized and that it has closed its auxiliary contacts which com-
plete the switch circuit of SCR board assembly (terminals 6 & 7 on Woods SCR boards).
• Check for 230V present across AC line terminals L1 and L2 on SCR board assembly (with unload
auger operating).
• Motor field terminals (F1 [+] and F2 [-] on Woods make boards) should indicate 190-200V DC. If
no voltage, replace SCR board.
• Check SCR board terminals 1 and 3 for 10V DC.
• Check SCR board terminals 2 and 3 for 1-10V DC varying with speed setting (with Meter Roll
Selector Switch in manual). If no voltage or voltage does not vary, check SCR speed control pot (on
ASC panel) or wiring to pot.
5. Turn SCR speed pot fully clockwise; check DC voltage between ARM. A1 (+) and A2 (-) terminals on
SCR board. Voltage should increase from near 10V DC to 155V DC as speed control is moved to
the MAXIMUM SCR speed setting. If no voltage or erratic voltage is indicated, check for possible
bad wiring connections or a defective speed pot before replacing SCR board. Check for voltage on
load side of armature fuse. Replace fuse as required.
6. Inspect wiring connections and check voltage applied to motor leads in motor junction box to deter-
mine if DC motor is bad. If there is no DC voltage, suspect a blown armature fuse or SCR board
assembly.
1. Burner switch must be ON.
2. Check for 230 volts across burner side of fuses located within fan-heater control box. Replace
fuses, if blown, and determine cause of excess current (shorted wiring connections, etc.).
3. Check for 230 volts across Burner Control Circuit (PL) terminals 1 and 5. If there is no voltage,
check for improper wiring connections. See BURNER CONTROL CIRCUIT wiring diagram in
Section 8 for circuit details.
4. Check for proper voltage across PL terminals 1 and T. If there is no voltage, check burner switch
circuit.
1. Check gas supply. Also, check gas filter and gas line for possible obstructions or closed valves.
Refill tank and service parts, as required.
NOTE: The electric Main/Safety Gas Shut-off valve cannot be opened until after the dryer control
circuit has been energized.
2. Check for proper voltage across Burner Control Circuit (PL) terminals 2 and T. If there is no volt-
age, check for a defective flame switch or improper burner switch circuit wiring.
3. Check voltage across PL terminals 2 and 3. If no voltage, substitute a new control relay and time
delay relay assembly, then repeat the test. If these new parts do not correct the problem, replace
the printed circuit base and repeat test.
4. If 230 volts is present across PL terminals 2 and 3, but burner will not operate, check the following:
A. Inspect gas solenoid valves (includes liquid valve on LP units) for defective coils or improper
wiring. Replace valve or valve coil if valve will not open with proper voltage applied.
B. Inspect for a defective high vapor thermostat (LP models only). Replace thermostat if its circuit is
open (without overheated vapor).
61