My fan directional control stopped working

I don't see a broken wire, but if you have a broken hard plastic vacuum line, that will cause the system to go to defrost mode for safety. It is spring-loaded to do that. Your feet might freeze but the windshield will be clear. The red arrow is pointing to the check valve for that vacuum line.

Okay, I may be slow, but I'm not stopped completely! Now I think I see what's broken. My sad red and blue arrows are pointing to the two ends of the hard plastic vacuum hose. That vacuum leak is relatively small but it will result in a higher than normal idle speed without a corresponding increase in power.

The repair is real simple. An inch-long piece of rubber vacuum hose is all you need to splice the two ends together. Any auto parts store will have it on bulk spools but they usually want to sell it by the foot. Instead, drive to any salvage yard. When you get there, twist and pull on the rubber connector, (green arrow), to pull the part off with the blue arrow so you can take it in and match it up to a piece of hose. If they aren't busy on the phones one of the guys may just chop a piece off something and give it to you. If you have one of the pick-your-own parts salvage yards, almost any car will have some hoses the same size. You want one that slides on somewhat hard so it won't come off. If you can only find something that's close and slides on real hard, spray it first with Silicone Spray Lube. That goes on like water and makes rubber parts like heater hoses slide over metal parts REAL easily, then it evaporates.

The piece of hose should be long enough to slide on far enough so it won't come off, but it should be short enough so the two ends of the plastic hose end up close to each other. That will reduce the tendency for the rubber splice to bend and kink.