Pitco MG14S-C/MFD, Service Manual, Page: 10 / 39

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Transformer:
Transformers are multiple input voltage, 24 volt out-
put voltage and can be checked by reading the input
and output voltages.
Blower:
Check the voltage between the wires going to the
Blower. If 120 VAC is found and the Blower is NOT
turning it is defective.
Pressure Switch:
As the blower speed rises the amount of vacuum on
the suction side of the pressure switch rises past ap-
proximately 1.3" WC (0.325 kPa) the Presssure
Switch will close. When the vacuum falls below ap-
proximately 0.8" WC (0.2 kPa) the Pressure Switch
will open. With the Blower running, check the IN
and OUT voltage of the Switch. If 24VAC can be
found on one side but NOT the other the Pressure
Switch is defective.
Gas Valve:
The Knob should be in the ON position. Check for
24VAC between the terminals marked MV and MV/
PV and between PV and MV/PV. If voltage IS found
between both of these connections and the Gas Valve
does not open the Gas Valve is defective. If voltage
is NOT present at both of the coils on the Gas Valve,
troubleshoot and repair the machine until voltage IS
present at both coils, retest the Gas Valve as previ-
ously described.