Question about Goodman GMS90703BXA Heater
Hi-- my furnace heater only blows cold air. From the therostat, if I keep the fan on auto, no air at all. When I turn the fan to on, air blows but it is cold. I can hear the motor/fan running. In looking at the furnace in the crawlspace, I pulled the front panel and had my wife turn the system on with the fan in the on position. The motor turns on, but there is not any flame.
From doing some research, I think I have a bad ignition switch or a bad circuit board or fuse burned out? Any ideas?
I have a TEMPSTAR 5000 (?) which is 15 years old.
I believe you are referring to the blower IN the furnace that distributes heat, not a power ventor which is used to expell flue gases when there is no chimney. I seems the answers given where in that direction. That being said, my answer addresses the blower for heat distribution IN the house.
I think what you are referring to is the fan limit. This senses the temp in the heat exchanger typically via a bi-metal coil that will expand and close a contact, sending power the blower when the preset high temperature in the exchanger is reached. This switch will also turn off burner if temp in exchange reaches max or "high limit", leaving the blower to run until it reaches a "low limit". One possiblility is the bi-metal coil is worn out, thus not responding to temp fluxuation.
A quality technician should never diagnose unless they are in front of the appliance. Hope this helps.
Posted on Feb 21, 2013
I work at a private school and we have three Tempstar furnaces that are going on ten years old. The problem, nine times out of ten, is the schedule on the Honeywell thermostat.
First, make sure the time and day are set correctly.
Second, set temperature and press 'Hold temp.'
Third, press 'Schedule,' it will display monday through friday and display 'wake,' set the time to wake at 5 pm; press 'schedule' and set time to leave at 11 am. set the same times for 'return' for 5 pm and 'sleep' for 11 am.
Do not set scedule for two PMs or two AMs. For example I set the schedule to wake at 5 pm and wake at 3 pm. It did not work at all and only blew cold air. It has to wake in the PM and sleep in the AM.
Then set 'schedule' for Sat through Sun. When saturday and sunday actually roll around the schedule will probably have to be reset again. So set schedule to wake at 5 pm and sleep at 11 am.
Fourth, press 'Run Program' then put thermostat under lock and key and hire an armed guard to stand watch and make sure nobody touches it or looks at it wrong. If somebody comes along later and hits 'hold temp,' it shuts everything down and starts blowing cold air again.
If that does not work, your next step is to make sure everything is clean, change filters, etc. Around the burners are two or three manual reset sensors. Shut down the power, remove the front panel, locate the sensors. They are round black gidgets that are attached by two red wires and two red terminals. Unscrew them and make sure they are clean.
If none of this works, then you need to get professional help for both yourself and your furnace. I did.
Posted on Jan 31, 2010
Sequence of operation, Gas Furnace.
On a call for heat, the 24 volt thermostat sends a signal to the control module. The control module will indicate a call for heat with a light on the control either blinking or remain solid depending upon model. The inducer (exhaust) blower will purge all gasses from the furnace and pressurize a pressure switch. Once the pressure switch tells the module to continue, the electronic ignition will energize and send 120 volts to the ignitor. The ignitor will glow and you will be able to see it if viewed thru the small inspection port. Once the ignitor gets hot enough, it sends a signal to the module opening up the gas valve (24 volts). Either a pilot will come on or the burner tube will ignite then spread the flame to all burners. Lastly a safety sensor will be looking for a certain temperature within a few seconds and the furnace will continue to operate and the room air blower will turn on in a minute or two.
What could go wrong? The unit will not run if there is no signal from the thermostat (bad thermostat or broken wire), the control module does not sense a signal from the thermostat (bad control), the inducer does not energize (bad motor), the pressure switch does not close (blocked vent piping, bad switch, plugged condensate hose), the ignitor does not energize (bad control, bad ignitor), the gas valve does not open or there is no gas (bad gas valve, broken wire, no gas), the pilot does not lite (dirty pilot), the burner does not lite (bad burner, plugged orifice, not enough combustion air), the flame does not spread to each burner (bad flame spreader, dirty flame spreader, more bad burners), the flame safety sensor does not detect flame (dirty or bad flame spreader, bad flame sensor, broken wire, bad control), or the room air blower does not energize (bad fan motor, bad control).
Most newer furnaces will have a diagnostic center or control built into the control module. You may be able to view it as it is running thru a small viewing port. Some models will require the removal of an access panel prior to finding it. On the reverse of the access panel, there will be a diagnostic chart that will aide you in understanding any error code recorded (usually a blinking light).
This is why we technicians earn the big bucks!
Posted on Dec 08, 2008
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Posted on Jan 02, 2017
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