______________________________________________________________________ I had a professional come out yesterday to service my furnace. He cleaned the igniter and flame sensor and it started back up and worked until sometime today. It was flashing an error code indicating that there was a flame sensed, but the gas valve was off. I cleaned the flame sensor and its mounting locations with emery cloth and reinstalled it, but the error didn’t clear up. I tried to check the voltage at the terminal on the flame sensor and after having my meter in the circuit for about 10s. the error cleared itself. I turned the thermostat back on and checked the voltage again (-3.xx v) and it started up. When it was running, I got about 69 volts (with the – end at the flame sensor and + to ground). I’m assuming the flame sensor is bad and the furnace company is coming back out in the morning to install a new flame sensor. I was wondering if there is supposed to be some continuity between the terminal on the flame sensor and ground. How can you test the things? Also, would it be possible to get a copy of the schematic for future reference. Thanks. Replies: xenos Webmaster “Re(1):Trane Gas Pack – No heat” , posted Tue 10 Feb 20:22 ______________________________________________________________________ There should be no continuity between the sensor and ground however the unit thinks there is. Bad new is you may be looking at a new board. Xenos. The best way to escape a problem is to solve it. petebob “Re(2):Trane Gas Pack – No heat” , posted Tue 10 Feb 20:59 ______________________________________________________________________ Ouch! Any idea on cost? I was hoping that since the LED wasn’t flashing a controller error that it would be OK. I’m crossing my fingers. Any idea why putting my meter into the circuit would make it think everything is OK? It’s cycled several times now correctly and my guess is that it will be fine when the repair man comes back tomorrow with a new flame sensor. xenos Webmaster “Re(3):Trane Gas Pack – No heat” , posted Wed 11 Feb 05:27 ______________________________________________________________________ Hey thats actually good news it may be the insulation on the wire. See the sensor is putting a high voltage in the flame and the flame is conducting this energy to ground. Bad insulation would do he same. It could even be as simple as dust on the back of the board causing a high resistance short to ground. Xenos. The best way to escape a problem is to solve it. petebob “Re(4):Trane Gas Pack – No heat” , posted Wed 11 Feb 16:36 ______________________________________________________________________ Turns out it was the board. Do you have a wiring schematic for this furnace. YCC030F1MOBE. Thanks, xenos Webmaster “Re(5):Trane Gas Pack – No heat” , posted Wed 11 Feb 19:28 ______________________________________________________________________ Email me at xenos@HVACMECHANIC.COM AND i WILL SEND IT. Xenos. The best way to escape a problem is to solve it.