someotherguy
Truly Awesome
You can see in that old pic of mine that sucker is almost completely obstructed with caked-on mud (dust from the air intake combined with the damp coils, it's a natural), and pine needles/leaf debris.Usually its the lack of airflow that leads to a frozen coil
I took apart another when I was building my '94 3500HD project.. this core is from a '98 that had only around 100K or so on it, and the A/C worked seemingly fine. It was really dirty. Not as bad as the old pics from that '88 parts truck I posted earlier, but still surprisingly bad for the fact the A/C was still flowing air.
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It's worth noting you can do a *reasonable* job of cleaning this mess out without total disassembly of the air box, which requires pulling the dash and of course evacuating the A/C system of refrigerant. Big job. Pull the blower motor, *carefully* reach through with a small flexible vacuum hose to suck out loose debris. Then, cover your passenger carpet with trash bags or plastic sheeting and spray some evaporator core cleaning foam in there, then rinse it out thoroughly with water. You'll make a mess. It should get clean enough to hopefully not freeze up again, and should improve airflow noticeably.
Richard