It's Easter morning... and it's colder than Christmas morning... and my 5-year new Goodman GMNT furnace is not working. Getting 4 blink code, main / auxiliary switch error. I have turned unit on and off and have it working, however when it shuts down and I think the blower continues to run causing a "hot electrical" odor. Afraid to keep unit on over night making house very cold by morning.

How do I diagnose problem and fix.

Thanks for your help.

You need to call for service. It sounds like your blower motor or heating elements are not working correctly. Check your air filter and make sure all ducts and return airs are open.

Thanks for the reply. I cleaned the blower last night, it was dirty aroung the motor, and the system ran well at first then had the same error. Is there a way to expose the heating elements for cleaning?