I have a Lennox gas heater in my home and the blower does not work on auto, only on manual. What is wrong?
filed in Home & Garden on Feb.15, 2010
The heater is "kicking on". That is, I can hear the actual heating unit turn on. But the main blower will only work if the manual fan is on. And even then it does not blow warm air. I was advised that by turning the thermostat off and back on that the heater would reset but this does not seem to work either. Any advice is appreciated.
February 15th, 2010 on 6:31 am
After the "fire"starts in the heater, it has to warm up a thermocouple to turn on the blower, so it takes a little while for blower to kick in, and when it shuts down the "fire" stops but the blower should keep going for a minute till it cools down. In the "manual" position the blower runs for ventilation, not heat. "Auto" is for heat.
February 15th, 2010 on 6:31 am
If it only works on auto then the wire going from the G terminal on the thermostat to the G terminal on the heater is not connected or broken.
If it runs but doesn’t blow then it could be a burned out motor,broken belt,bad fan/limit switch or plugged filter
February 15th, 2010 on 6:31 am
I would say the burner is not actually lighting.
It would be blowing warm air when you put the fan switch in the on position.
Your probably hearing the combustion motor running.
Since there are so many different models its hard to say what the problem is, it could be a cracked igniter if it has one or a pressure switch or limit switch or a variety of possible problems.
You could start out trying to find a diagnostic light on a circuit board or control if it has one.
February 15th, 2010 on 6:31 am
Based on your description, your power ventor motor is turning on and that is what you are hearing. It has to come on to vent the products of combustion out of the house. The main blower will not turn on in auto mode until unit has fired up for a short time. In manual mode the fan will run until you shut it off. Your unit is not firing up if you do not get warm air through the vents after a short period of time from initial start-up. Most units will attempt to light a series of times(usually no more than six) and will go into lockout. Indicated by a flashing led bulb on the gas valve or circiutboard. Some models will reset themselves after a set – time and will cycle again as long as t-stat calls for heat. Some models have a sight glass to view the flashing bulb and others do not. Most common problem is that the hot surface igniter is bad or something as simple as blocked venting. Do not know of how many times I have removed kids toys from exhaust vent pipes. If unsure of what you are doing, please call in a licenced service technician to investigate. At said time, have them do the required annual service if not already done. IT STATES IN MANUAL TO HAVE SERVICED ON ANNUAL BASIS BY QUALIFIED TECHNICIAN. Most people do not know this because they choose not to read the manual for the unit or none exists.
February 15th, 2010 on 6:31 am
Turn the breaker in the breaker panel off for 20 seconds. Then back on. If it still fails to operate call in a Tech.