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Tiffany2 11-03-2012 11:11 AM

No Power to Combustion Air Inducer
My Furnace Lennox G40UH (X) 48B-090-07 does not have hot air. LED 1 flashes, LED 2 is On.

1. Already checked Primary and secondary limit switches.
2. Already cleaned the hose of CAP & CAI.
3. Already checked all cables, caps, loose connectors.
4. Already check filter duct.

1. No power (115V) goes to inducer (inducer itself works fine)
2. When on power, blower ran, but inducer just started and then stopped immediately.
3. Ignitor did not light up at all.

Please help me out. Thank you without end.

notmrjohn 11-05-2012 09:17 AM

1. If no power how do you know inducer is working?
LED code says you have an open limit switch. If switch does not close within a pre-set time, ( usually 2-3 minutes) the safety override turns unit off for about an hour, unless you reset it.
The read out of an open switch may not be precise, it doesn't actually check the switch, but diagnoses from symptom caused by open switch. Since inducer starts then stops, check that plastic tube to inducer and prssure sensor is connected at both ends.
I think other checks are going to need a muti-meter. Check this site, your problem is the first one addressed.

In mean time, I'll see if I can get a friendly admoderstrator to move this thread to HVAC forum, where the experts hang out, shooting the breeze, or trying to fix the breeze shooters.

Wuzzat? 11-05-2012 10:52 AM

If you have a multimeter and a legible schematic you can post there are systematic ways of troubleshooting this.
Even if it takes you 8 hours to fix the problem you'll still be paying yourself a goodly sum for your time.

notmrjohn 11-06-2012 06:40 AM

Check that you have your thermostat set high enough for furnace to come on, though I do not think it is your problem. Just the other day someone had problem with water heater that sounds a lot like yours. Vent fan/inducer came on , then went off when manually started, no ignition, turned out thermostat was set lower than usual.

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