I've thought about this because my air diverter valve does not work properly. All I have found on the dash air/heat subject is this:
https://www.justanswer.com/rv-motorh...otor-home.html That article suggests the heater core may be accessed by removing the black box on the exterior of the firewall. You could ask your own question there too.
and:
https://www.winnebagoind.com/resourc...g%20&%20AC.pdf
Have you looked up your dash air on the Winnebago schematics website, the link is in a sticky at the top of this forum.
If it was the fan, I hope it didn't destroy the heater/air conditioner exchangers.
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2000 Winnebago Ultimate Freedom USQ40JD
, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA.
" My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy