No heat. Customer stated he had to keep hitting reset on primary. Turned thermostat on and furnace fired up. Turned power off to unit 10 times and burner fired up each time. Removed nozzle assembly and found nozzle completely plugged. Replaced nozzle and air filter. Let system run and primary did not trip while I was servicing system. System needs a cleaning, customer took out MA we will schedule cleaning for customer. Please mail invoice.