matthew13sanderson

Completely different vehicle, but a couple of buddies have Honda civics with the a removed, and the defrost works fine.

Back to my question, do I need to get this fixed? I'm still not totally sure what it does.

87f-150

Yes fix it. It can be fixed with a piece of rubber vacum line .

rikard

That vacuum motor switches between outside air and recirculating cabin air. Its primary function is to cool down the cabin faster when first putting on the A/C but closing off the outside air.
Using the compressor in defrost mode does clear the windsheild faster and shouldn't shorten compressor life. You can always install an aux switch to switch off the compressor.
Regards
rikard

sylver91

Not using the compressor shortens its life, having it engaged and pumping cycles the oil through it, keeping it and the seals lubricated to prevent the freon from leaking and the compressor from locking up.

Warlockk

X2 ya beat me to it. That's why vehicles that have been sitting usually have non functioning Ac.

sylver91

Yup and that goes for any part of the vehicle. Start something up and drive it that has sat for years and its gonna leak, even if it didn't when you parked it.