Lennox G20 with electronic pilot. Not induced exhaust. Main problem is that the main burner will not ignite. All systems check out until I get to the voltage to the gas valve. Pilot voltage is 27 VAC and pilot works as expected; sensor heats up and turns off the spark; pilot continues. The main valve, which does not turn on as set up will not operate so the main burner never gets gas. Here is where it gets interesting. Take the main gas lead off of the valve and it shows 27 VAC, when it should. However, when the lead is connected to the valve and I take a parallel measurement of the main and common terminals I only read 14 volts AC and the valve does not open. Also, if I jump from the pilot terminal to the main terminal, the main valve will work, the main burner lights and the furnace heats up as it should. All grounds check out.
Any ideas? My guess is the ignition control unit (which does not have a status LED.)
↧
