Hi Everyone! The little green light that lights up when the AC is engaged wasn't working on my 1992 FJ80, so I determined that there's an LED inside that had failed. I didn't find a guide to fixing it, so I figured it out myself. Here's how I did it. I think this only applies to 1991 and 1992 80's; the ones with cable-driven controls.
To remove the AC switch, apparently you can just tug on it and the module slides out. I didn't know this so I took apart my whole dash. Both ways work just fine.
Once the module is out, take it inside to a clean and well lit workspace. Don't open it up inside the truck!
Remove the small lightbulb by turning the plug (mine is white) counter clockwise. I had to pry on it with a flathead to get it out all the way. This bulb lights up the words "A/C" on the button, but not the green indicator itself. It has to be removed to take the switch apart.
On either side of the module, there are two small slits that hold the locking tabs in place. Gently pull on the button while poking these tabs with a small flathead. Once it starts to move, don't take it all the way out. Here's the unit halfway taken apart, and one of the slits is circled in red.
On the bottom of the module, there's a spring that handles the click in/click out of the switch. You can see it above. This spring is under some tension and can shoot out once you pull the switch outside of the outer cover. Cover the spring when you pull it out. Here's the module taken out of the cover, and the spring removed. I placed it aside as it kept wanting to launch out of the housing.
With the spring set aside, stand up the inner module with the pins facing up. You'll need to gently pry the tabs circled in red and fold the PCB away from the switch housing. Here's those steps.
With the PCB free, check it for any damage. On some, I'm sure it's possible the resistor (blue) might have failed, but mine was fine. It measured I think 269 ohms. In my case, the LED itself was bad. I had a replacement on hand, but any regular 3mm LED should work. I used a green one, but other colors would work as well. Here's my replacement. Note the polarity! It does matter. You can use the flat edge of the LED, as well as the "cup" structure inside it to determine the polarity.
Desolder the bad LED. Use whatever method you prefer, but never pull on the leads when the solder is frozen. You can damage the board that way. Remove all the excess solder so the holes are opened.
Insert the new LED using the black plastic guide and making a note of the spacing. Make sure the polarity is correct, too! Once everything looks good, fold/trim the leads and solder it up.
Once it's soldered, ensure there are no solder bridges or other board defects. Now is a great time to smear some dielectric grease on the switch's pads.
Insert the PCB back into the switch assembly LED first, then snap it down in the rear.
Now, be careful to reinsert the black "clicky spring" and slide it back into the outer housing. Make sure the switch still clicks in and out, as the long arm of the spring must fit into its channel. If it's not in the channel, the A/C switch will only be a momentary one.
Snap the entire module back together, including the lightbulb, shove it back into the socket in the dash and go try it out. They key must be in and the blower switch must be on for the A/C light to light up.
To remove the AC switch, apparently you can just tug on it and the module slides out. I didn't know this so I took apart my whole dash. Both ways work just fine.


Once the module is out, take it inside to a clean and well lit workspace. Don't open it up inside the truck!
Remove the small lightbulb by turning the plug (mine is white) counter clockwise. I had to pry on it with a flathead to get it out all the way. This bulb lights up the words "A/C" on the button, but not the green indicator itself. It has to be removed to take the switch apart.


On either side of the module, there are two small slits that hold the locking tabs in place. Gently pull on the button while poking these tabs with a small flathead. Once it starts to move, don't take it all the way out. Here's the unit halfway taken apart, and one of the slits is circled in red.

On the bottom of the module, there's a spring that handles the click in/click out of the switch. You can see it above. This spring is under some tension and can shoot out once you pull the switch outside of the outer cover. Cover the spring when you pull it out. Here's the module taken out of the cover, and the spring removed. I placed it aside as it kept wanting to launch out of the housing.

With the spring set aside, stand up the inner module with the pins facing up. You'll need to gently pry the tabs circled in red and fold the PCB away from the switch housing. Here's those steps.



With the PCB free, check it for any damage. On some, I'm sure it's possible the resistor (blue) might have failed, but mine was fine. It measured I think 269 ohms. In my case, the LED itself was bad. I had a replacement on hand, but any regular 3mm LED should work. I used a green one, but other colors would work as well. Here's my replacement. Note the polarity! It does matter. You can use the flat edge of the LED, as well as the "cup" structure inside it to determine the polarity.

Desolder the bad LED. Use whatever method you prefer, but never pull on the leads when the solder is frozen. You can damage the board that way. Remove all the excess solder so the holes are opened.

Insert the new LED using the black plastic guide and making a note of the spacing. Make sure the polarity is correct, too! Once everything looks good, fold/trim the leads and solder it up.



Once it's soldered, ensure there are no solder bridges or other board defects. Now is a great time to smear some dielectric grease on the switch's pads.

Insert the PCB back into the switch assembly LED first, then snap it down in the rear.


Now, be careful to reinsert the black "clicky spring" and slide it back into the outer housing. Make sure the switch still clicks in and out, as the long arm of the spring must fit into its channel. If it's not in the channel, the A/C switch will only be a momentary one.


Snap the entire module back together, including the lightbulb, shove it back into the socket in the dash and go try it out. They key must be in and the blower switch must be on for the A/C light to light up.
