Lennox EL196UHE Series Information page 17

Pressure switch stuck closed
Pressure switch does not close due to obstruction in vent
pipe.
Pressure switch does not close due to incorrect routing of
the pressure switch tubing.
Pressure switch does not close due to obstructions in the
pressure switch line.
Pressure switch tubing damaged.
Condensate in pressure switch tubing.
Pressure switch does not close due to a low differential
pressure across the pressure switch.
Wrong pressure switch installed in the unit, or pressure
switch is out of calibration
Miswiring of furnace or improper connections at pressure
switch.
Pressure switch failure.
Damaged condensate trap.
Cold end header box does not drain properly.
Air leakage around the combustion air inducer gasket.
Air leakage around the cold end header box gasket.
Damaged cold end header box tubing.
Problem
TABLE 8
Check that the pressure switch is open without the com-
bustion air inducer operating. Replace if defective.
Check for restricted vent. Remove all blockage. Check for
proper vent sizing. See table 13.
Check that the pressure switch tubing is correctly routed.
Correctly route pressure witch line.
Remove any obstructions from the the pressure switch
line and/or taps
Check pressure switch tubing for leaks. Replace damaged
tubing if necessary.
Check pressure switch tubing for condensate. Remove
condensate from tubing.
Check the differential pressure across the pressure
switch. Check for restricted inlet vent. Remove all block-
age. Check for proper vent sizing and run length.
Check that the correct pressure switch is installed in the
unit. Replace pressure switch if necessary.
Check for correct wiring and loose connections. Correct
wiring and/or replace any loose connections.
If all the above modes of failure have been checked, the
pressure switch may have failed. Replace pressure switch
and determine if unit will operate.
Check trap for any cracks or damage and replace if nec-
essary.
Check that the furnace is set properly with a slight tilt (0
- 1/2") towards the front if necessary. See furnace installa-
tion instruction.
Check gasket and replace if necessary.
Check gasket and replace if necessary.
Check tubing and replace if necessary.
Page 17
Corrective Action