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Run 24volts to valve and blow air through valve to see if it opens

If so hook it to the terminals on the vavle turn on the heat and read the voltage should be at least 24 volts

Do you have a multimeter

Look on the side of the valve or if you still have the box read the specs on the box

It should be on the valve

Check your gas pressure at the valve

According to the model # you have a 2 ton system

You might have a bad timer

Get a real electrician no such thing is two phase only three phase and single phase

Check vent and take dryer apart and vacuum inside of dryer because it's probably full of lint

Find the timer manuely turn it to defrost ir the heater turn on change the timer if not replace heater and themostat assembly

Check the high limit switch for continuity, if it's open replace and make sure exhaust vent is clear