[ec2000]

I have a Frigidaire FG6RK072C-12 furnace for about 7 years. It started to have problems a couple days ago. The motor was running and then ignitor was on. But the burner might on for a short period and then cut off or it would start and cut off right away. I got a "pressure switch stuck closed" indication. Even I changed a new pressure switch, I still had the same problem. The system seamed quite sensitive, I just touched any wire, it started a new cycle again. Note that I did try to make sure all connections are properly connected. Could this likely be the control board problems or I should open up the motor to do some clean up/rubrication?

[hvac1000]

If you touch any wire and it does that the first thing I would check is for a bad or corroded ground connection. Check and report back. The ground wire is supposed to be green but can be any color. Loosen wire then retighten.

[ec2000]

Thank you hvac1000! Your suggestion was quite good since it triggered me to review all connections of furnace one more time. The ground wire connection was fine. I used a volt-meter to make sure the ~0 ohm. After turned on the power, I touched the white wire from thermostat and ground. I did get ~26ACV and you know what the furnace was running as normal until I took out the measurement. I tried this twice and got the same behavior. So I checked the wires from the thermostat t the control unit. I found the yellow wire a little bit loose so I secure it. It runs now and hopefully it will stay this way.

[hvac1000]

Good deal glad you got it fixed.