I have an Armstrong sx90 gas furnace w a/c. The furnace circulating fan quit operating. The tech replaced the circuit board (part no 40403001) which had a burnt diode. Now the fan operatesin all functions, but stops as soon as the compressor stops. It used to run on for a minute or two after compressor stopped. An solutions?

The blower conrol board has a time delay off setting on it. You paid good money to have it put in, call them back to finish the job.(I say warranty call back.) My blower has never shut off it runs 24/7. I have my thermostat set for fan ON all the time. It keeps a more constant whole house temp. Blowers a made to run around the clock if you want them to and at very little cost.