d. 7 RED FLASHES: This fault code indicates that the flame could not be established during
three trials for ignition. The furnace will lock out for one hour and then restart.
e. 8 RED FLASHES: This fault is indicated if the flame is lost five times (four recycles) during the
heating cycle. The furnace will lock out for one hour and then restart.
f. 9 RED FLASHES: Indicates reversed line voltage polarity, grounding problem, or reversed
low voltage transformer wires. Both heating and cooling operations will be affected. The
furnace will not start the ignition sequence until this problem is corrected.
Diagnostics and Trouble Shooting Guide.
This fault may be caused by one or more of the
following, and each should be verified as to being either a potential cause or not:
a. Malfunctioning Gas Valve - Check for a leaking or slow-closing gas valve. Correct for
leaks and/or replace as necessary.
b. Gas supply irregularities such as momentary loss of gas supply, flame blowout– these
failures result in a disruption in the flame and are typically sensed within 1.0 s. The gas
valve de-energizes and the control begins a recycle operation. A normal ignition sequence
begins after a 15 s inter-purge. If during the five recycles the gas supply does not return,
or the fault condition is not corrected, the ignition control locks out for 60 min.
Check that
the gas valve switch is in the ON position. Check for low or no gas pressure, faulty gas
valve, dirty or faulty flame sensor, faulty hot surface ignitor, loose wires, or a burner
problem. Verify natural gas input rate by clocking meter. If clocked rate does not match
the input rate from the unit nameplate, follow steps in the manual to adjust the manifold
pressure. In addition, examine the burner flames to make sure they are in good
adjustment. Look to a pure blue flame with a light blue cone at its center that burns full,
steady, and straight. If yellow or orange, partial, diverted, or unsteady flame is detected
then turn off gas valve and clean any debris from nozzles and burners. If condition still
exists then check airflow, venting, gas pressure, etc. If condition still exists, contact the
Johnson Controls Field Service Support staff for further information and directions.
c. A momentary loss of power for 50 ms or longer during burner operation, - this will typically
de-energize the gas valve. When the power is restored, the gas valve will remain de-
energized, and the ignition sequence will immediately restart. Check the IGNITION
CONTROL FLAME SENSE LEVELS. Normal flame sense current is approximately 3.7
microamps DC (
μ
a), Low flame signal warning starts at 1.5 microamps on most models.
Low flame signal control lockout point is 0.5 to 0.1 microamps DC (
μ
a) depending on
furnace model.
d. A faulty flame probe or flame probe circuit
-
verify field wiring to the unit is properly
grounded, re-verify ground wires and conductor connectors are tight and secure. Check
polarity at furnace and branch. Check that the flame probe exhibits proper electrical
continuity and is not shorted to chassis. Only clean flame sensor using 0000 fine steel
wool.
e. Obstructions in the heat exchanger/exhaust venting system – Examine the heat
exchanger, vent pipe, combustion air passages, vent connectors, and chimney to be sure
they are clear and free of obstructions. Note: proper orientation on the heat exchanger is
for the compressed heat transfer blade portion to be up and away from the burner section
(as shown in the image above) and if applicable, towards the add-on indoor coil cabinet.
