Troubleshooting a Gas Control Valve
My furnace (Sears NTP6) has not been working for over a week. Its had a "Soft Lockout error". I finally got a Sears service guy to look at the furnace and he tells me my Gas Control Valve (SV9540Q2456) needs to be replaced at $700 for parts and labor.
I did some investigation and found a troubleshooting guide for this controller:
After the service man left I started going through the troubleshooting guide.
Step one Â Checked the pilot burner element - ohms to be less then 10. Everything OK there.
Step two Â Turn off gas supply, Make sure the smartvalve is set to "On", Disconnect the control harness, and set the thermostat to "Call for heat". Â OK
Step three Â Check for the proper voltage at the control harness. This should be 24V from Common to Thermostat (or pressure switch) and 24V from Common to "Hot". = THIS WAS NOT OK. I got 7.5V from Common to thermostat and 0.075V from Common to "Hot". The troubleshooting guide calls for something other then the gas control valve as the problem (Most likely the power board Â which is under warranty).
Strange thing here is that the service person had the power board or the Fan controller board (208907) as needing to be replaced under warranty but told me that was a mistake and the gas valve was what needed to be replaced.
Can someone instruct me on the voltage issue and tell me if I am on the right track given the situation.