atwood 8500iv

[noshi]

I have discovery 2003 2 zone furnace .zone 2want start has code air flow fault dont know wat to do. help

[Rook]

Fan must be running or burner will not light. Is it running? Rook

[Hooligan]

noshi- Try this list of service manuals and troubleshooting. Furnaces are down the page.
Service Documents
Hydroflame = Atwood... (if the fan is running it may be the sail switch..)
hope this helps

[Gary RVRoamer]

if the fan isn't running, that's the problem. If you can hear it running, then the problem is that it is not running fast enough, i.e. not moving enough air to engage the sail switch. This can be caused by low battery voltage, or by blockage in the air path. Since a single motor drives both the intake/exhaust fan and the air circulation fan, a blockage in either one causes problems in both.