Lennox EL280UH110P60C Unit Information page 16

Test 1 Checking resistance of ignitor circuit
Remove 5−pin plug from integrated control.
Check Ohms reading across terminal 1 and 5.
Reading should be between 39 and 70 ohms. If
value is correct, this is the only test needed. If
the meter reading is not correct ("0" or ifinity),
then a second test is needed.
Meter
(set to ohms)
Test 2 Checking the resistance of the ignitor
Seperate the 2−pin jack plug near the manifold and check
resistance of the ignitor. Reading should be betwenn 39
and 70 ohms. If reading is correct, then there is a problem
with the wiring between the jack plug anf the control. If
reading is not correct, the issue is the ignitor.
Meter
(set to ohms)
Test 3 Checking voltage to ignitor
Insert meter probes into terminals 1 and 5.
(use small diameter probes in order to not
damage plug). Check voltage during 20
second ignitor warm up period. Voltage
should read 120 volts + or − 10%. If voltage
is above or below these values, check for
correct supply voltage to furnace.
Meter
(set to AC volts)
EL280UH Ignitor Check Out
FIGURE 9
Page 16
Integrated control detail
Integrated control detail
Integrated control detail