My heater won't work and the kids are cold! Its flashing a very rapid code that suggests reverse polarity. But its been here since 2002 so that doesn't make since. When I turn it on I get the rapid code, then the fan comes on for 90 seconds then it shuts down. No inducer and no gas or igniter. I've checked the pressure switch. Its opening and closing with my mouth and I've checked the wiring it looks good