I would suspect you may have a low refrigerant level. You need a set of gauges to see what is really going on. But that is a sign of the low pressure switch kicking in and out.

Check the easy thing first. Check your fuse box and find the AC Fuse and (it is 12 on my 86) for good contact and shiny posts.

Then you need to see if the compressor comes on. One quick way to make sure is to reach under the intake hose and locate the two connectors with the green wires and jumper the wires so that the compressor bypasses the low pressure switch. If you do not feel like digging around under that intake hose and AMM you can take two spade lugs and make a little jumper. Then you take the two spade connectors off the low pressure switch and add the jumper. That should have 12 Volts so watch what it touches. Crank her up and see if you hear the compressor running, there will be a delay of a couple of seconds before it kicks on. The system may be blowing cold air with the bypass in place. A system with low pressure will still do a decent job of cooling. The low pressure switch is there to save you for wearing out the compressor and doing all sorts of other bad stuff. Unless you want to burn up your compressor do not run it that way long. The good news if that is this works you are just a couple of cans of Freon away from burrr.

The fan will not kick on until the Freon reaches a certain temperature so there may be nothing wrong with that. Check the fuse and compressor running on the low pressure bypass before you chase that rabbit.

Good luck and may your AC blow cold and the idle be smooth.

Regards,

PT