Well, here is another question related to my OLD carrier furnace. Again, it is a 58DXA060-101GG (or 100GG.) The issue is that during the day it seems to do pretty ok as far is starting a heating cycle. At night/early morning it seems to be a different story. The thermostat will call for heat, the inducer motor will start up. After a pre-determined time (1 minute?) it shuts off. The thermostat is still calling for heat. If I power cycle the system either from the thermostat or the circuit breaker, or furnace blower door switch, it will run the cycle again and 9 out of 10 times it will continue as normal. Sometimes during the day/evening it will do this as well. But usually we wake up to a house, set to 68-72, and it is 62-66.
I have replaced the pilot once before (3-wire spark pilot), and it still had the issue. I replaced the ignition lockout control, still same issue. These 2 items were "diagnosed" as issues by an HVAC repair person. Obviously they were not the solution. I can't make the furnace replicate the issue, because when I power cycle to test the furnace, it "resets" and works fine. If I don't power cycle, the furnace stays in lockout and I can't take any readings.
I really don't want to throw money replacing parts in hopes it fixes it. My next parts on the list of possible problems are the main control board and the gas valve. I have read similar issues on other sites that people replaced the main control boards and that solved the problem. The furnace is so old that it doesn't have and LED or other indicator to show an error code. So that option is out. Also no flame sensor in this furnace as the 3-wire pilot is a b-metal switch that acts as a flame sensor. Any suggestions?
My plan was to buy the control board next. It looks like the new replacement versions have LED lights, which could help in the future.
Other observations include: Spark igniter will spark for an extended period of time sometimes. Pilot light will sometimes "sputter" and the igniter will spark again to re-light.