Ok some of these pics are where I pulled the blower motor and shoved phone up there, but this is the intake side (RH) of the evaporator. Previous owner must have hated recirc and loved eating dust. Before:
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Another:
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Soaked with Simple Green:
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Rinsed out:
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Like you everything else checked out but the air flow just wasn't there; blower changes speed, all the doors open/close, freon/compressor good to go, even tried replacing the solid-state resistor thing. But all that crud on the evap just wouldn't let air through. BTW if you get any condensation in the cab check the heater box drain, it's on the firewall just rear (and almost impossible to see) of the RH cylinder head, might be clogged and that's where all this water and debris I flushed out went. Good luck!