Ok, time for some WTF is broken this time electrical trivia.

My 84 has developed the strange issue over the last week where the cabin fan will stay running after the car is turned off. Eventually it'll shut off, but it runs for several minutes, almost like the car has gotten confused about what fan to run until the car cools off!

Potentially connected electrical issue: A few weeks ago, I noticed that the radiator cooling fan would keep running indefinitely, long after it should have cooled off and shut down. Tapping on the cooling fan relay at that point would get it to 'click' and then turn off, like the relay was getting stuck on periodically.

So, I ordered a replacement relay. Turns out that I got the version for non-air-conditioning cars- it's got two fewer pins on the control side (the ones labeled A and B on the relay itself). Now, my A/C doesn't work, and I'm about 2 seconds from just deleting the whole system anyhow, so I don't actually care, so after consulting the wiring diagrams, I went ahead and plugged in the new relay (location 1 in the under-dash relay board, to be clear). Now, the fan doesn't come on at all. Still doesn't turn on when I put the old relay back in either, so there's apparently more to it than just the relay. I'm going to check the temperature sensor and the resistor stuff here this weekend, but it's strange that the new relay wouldn't work at least as well as what I had before. And the timing of this issue in conjunction with the other fan staying on after turning off the car is messing with me a bit.

Anyone had a similar problem before? I'm going to just go through the various wiring diagrams and see if I can track it down, but any suggestions on where to start would be appreciated!

 

REPLACE TEMP SENSOR IN YOUR RADIATOR

 

The AC circuit locks out the "heater fan"...and the rad fan should turn on when the AC switch is on.

My guess is, the different relay in your car, is powering the cabin/heater fan instead of the rad fan, because of the wiring differences.

 

Ooh, that actually would explain pretty much everything now that you mention it... And the original relay having died completely would explain why it didn't seem like it was behaving any differently... Feels like the wiring diagrams out there leave a LOT out, because based on pin names and their arrangement on the relays, this shouldn't make a difference electrically.

And to Giantviper's shouted point, I probably should replace the temp sensor just because I'm having issues with the cooling system, but tapping on a stuck relay causing it to make an audible click and then shut off points VERY strongly to the relay being a problem. I've not had any other issues with cooling until this, so I suspect the sensor is fine anyhow.