Thermo Pride GMC-85 Installation And Service Manual page 36

All installations and services must be performed by qualified service personnel.
After fuel valve opens,
does the burner ignite?
Yes
Does the burner stay
lit past proof of flame
check?
Yes
Does the fan timer
energize the circulating
air blower after the 56
second time delay?
Yes
For the GMC, measure gas
No
supply pressure at inlet to
gas valve. Is it at least 4.5"
W.G. for natural gas or 11"
W.G. for L.P. gases? For
the OMC, is oil present in
the fuel line at the valve?
Are the ignition electrodes
positioned correctly?
Check for blocked or severely
worn burner nozzle (OMC) or
burner orifice (GMC). Clean
or replace as required.
On the GMC, measure supply &
manifold pressures. Are they
constant over time and within the
No allowable ranges? On the OMC,
is the oil tank full of fuel? Is the
fuel clean without contaminates?
Is the fuel filter dirty?
Check settings on fan
timer against those
on connection
No diagram. Is blower
still inoperable
after time delay
with fan timer
set correctly?
No
Yes
No
Yes
Yes
No
may be too small for flow. On the
OMC, add or replace fuel and fuel
filter. Also, check flame sensor (GMC),
cad cell (OMC) for proper operation.
Measure voltage
on the circulating
Yes
air blower terminals.
Is it 120 VAC?
Yes
Does blower wheel
spin freely?
Yes
Is blower motor
capacitor functioning
properly?
Yes
Replace motor
35
Check the fuel supply.
Open all manual shutoff
valves serving the unit.
Purge any air in the
fuel line.
Reposition to
correct location.
On the GMC, adjust supply
pressure to 4.5" W.G. for
natural & 11" W.G. for LP gases.
Adjust manifold pressure to 3.5"
W.G. for natural gas or 10" W.G.
for LP gases. If gas pressure
fluctuates, a pressure regulator
may be required or gas piping
Check wiring to
blower. If okay,
No set fan selector
switch to manual.
If fan operates,
replace fan timer.
Check for blower wheel
No rubing against housing
or motor shaft spinning
freely. Adjust or replace
as necessary.
No
Replace blower
motor capacitor.