My daughter has a what the installation manual on it says is a G40UH(X) Series Gas Furnace and Air Conditioner in her house. All was working fine until this morning and it appears the blower has stopped working. They symptoms are: The blower does not come on in the AUTO or ON positions. When the thermostat calls for cooling, the condenser compressor and fan start up, but the blower does not come on to circulate the air. The line from the evaporator coil is cool, so I believe it's just an issue with the blower. I also put the blower setting on the thermostat in the "ON" position and the blower still does not run. I've shut off the a/c to keep the compressor from continuing to cycle in trying to cool the house without a blower. It's hot here in TX so a fix is needed asap.
I've opened the unit to check out the integrated control board during the attempts for the unit to run. The SureLight board has two LED's, both of which blink slowly (1/sec) at the same time, which the table on the panel indicates is "normal operation". I've checked that I do have ~24 VAC on some of the thermostat terminals, so it appears the unit is getting a signal from the thermostat (haven't verified that it is the right signal yet, but there is definitely a signal).
Went up there one more time in the sweltering heat and labelled/disconnected/cleaned and reconnected all the connections to the circuit board. I've got it to the point where it consistently acts as follows:
When powered on, both LED's blink simultaneously with a slow (one/sec) blink.
If set to COOL with fan in AUTO, condenser comes on as setpoint is reached but circultation blower does not come on.
If set to COOL with fan in ON (and I set the setpoint up high enough so condenser would not run since fan not running), circulation blower does not come on. Checking the voltage between the various terminals on the integrated control board, the only place I can get 120 volts is between "Line H" and "Line N" or "Circ N". There is no voltage on the "Cool H" or either of the "Park" terminals to "Line N"
Looking at the diagnostic codes (Table 4)in the attachment you provided, the slow simultaneous flash indicates "Power on- Normal Operation" and "Also signaled during cooling and continuous fan". Then I look in the Troubleshooting Guide for Problem 1 - "Unit fails to operate in the cooling, heating or continuous fan mode" and the Condition 1.4 indicating two slow flash LED indicate a problem with the combustion air inducer motor. Could that be the problem that is causing all of this?? Haven't checked it out yet - should I check it and if so, how? I did try putting the system in the Heat mode and setting the heat setpoint up high enough so that the system should kick on and nothing did. Is that a clue?
I'd like to bypass the control board to check that the blower itself is really working (as I'm starting to believe it's a problem with the control board). To do this would I install a jumper between the Line H to Cool H?? If not, specifics on how I can test the blower would be greatly appreciated.
Obviously I need help and guidance as to the right series of tests to apply to determine what is really not working and how best to repair it. I've tried to attach a copy of a manual I received that might be of help. Anyone to help to guide me through this would be greatly appreciated!