My AC units (dometic) work fine. I swapped out the vents. I found the ducting to be collapsed and used PVC to open then up, and placed some short pieces of PVC at each end of the ducting to prevent collapse and the air flow significantly improved.
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Mike and Lorraine
2002 3655 FL, 2005 3650RK
2010 3665RE, 2015 3910FB
F350 crew cab dually 6.7
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