Hi Jason,
Without the fan running you will have no AC as the fan not running inhibits the AC by default. As Grimbo says, what makes you say the gas is OK? Have you had it checked with gauges? Although cleaning the evaporator (shown in the photo) is a good idea, if you can get to it without ripping the dash apart, it isn’t going to cause the fan to not come on or in turn stop the AC system pulling the clutch in. Gas can be lost easily through leaking pipes and the 80 does have a couple of areas where pin holes can appear, along the pipe that is bolted to the firewall is one, rear AC if you have it can be another depending on corrosion issues. Low gas isn’t going to prevent your fan working though.
The fan would be the first thing to sort out and as Grimbo has said, first place to look is fuses. I had an instance where my fan stopped working and I bypassed it with a wire from the fusebox and a toggle switch in desperation one winter. After some time I reversed the bypass and it has worked faultlessly since. For the life of me I have no idea why it stopped or what happened to make it go again. Not much help I know but for it to inhibit the AC it must be something feeding the fan and climate control (which I guess is what you have, rectangle with buttons and slider across the bottom) rather than a problem with the fan.