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The normal sequence of operation:
Inducer vent motor comes on
Pressure switch closes
Main circulating blower comes on
If furnaces fails before ignition we should get an error code by blinking lights on the control board. Turn power off and back on, then call for heat.tell me how far in that sequence it goes and what error code is on first failure We will go from here.
Control board will be in blower compartment
Ok pressure switch is closing if igniter starts to glow. So lets start there.Do you have a volt meter for troubleshooting?
Let me ask you tis. After the igniter glows do you hear the gas valve click or any slight brief odor of gas?
We really need to know if the board is sending 24 volts to the valve to know how to proceed in troubleshooting so we are not guessing.You can get an inexpensive one at Walmart for about 15 bucks if you would like.
That will be great.That will tell us if the gas valve or pressure may be the issue or if board is never calling for the valve to open.
Just make sure to get a meter with leads and that reads actual voltage, not just on of those little 120 volt test lights that shows if a circuit is hot or not.Here is a sample.
Sounds great. If you happen to have access to a manometer or a gas pressure tester, bring that too. If we are getting 24v to valve we need to check inlet pressure to valve next.Talk tomorrow.
OK set the meter to AC volts. Lest put one lead on each of the gas valve terminals and call for heat.When igniter glows watch to see if we are getting 24v ac to valve.
What are the terminals labeled?
Ok on the mode switch on board are you set to 1STG or 2STG on dip switch?
Ok we should get 24v between both C and M and between C and HI
What is model on meter? Does it not read actual voltage?
OK if we are getting 27v the issue is either going to be gas pressure issue or bad valve.Do you have any other gas appliances that are working properly?
OK our next step is to check the gas pressure into the valve.Without having a manometer or gas pressure tester we are guessing. You can either take a chance that valve is the problem or get gas pressure tested.
Excellent. Thanks for allowing me to help to this point.