I was going to piggyback on this HOW TO thread by LordBiotree, but I cannot post there.

(This was done on my D21 Hardbody)

My A/C is original as far as I can tell. It is still on R12 and has always worked well.

Just before a recent club ride, I decided that it could probably work better with a little TLC.
One problem is that it was blowing cool all the time, and cold intermittently.
Another problem was that it was not blowing very hard from the upper vents.

Upon investigation, I found that I had three problems:
a partially clogged evaporator
a malfunctioning vent control
low refrigerant charge

I started by removing the blower from below the glove box. By removing two screws, a nut and the squirrel cage, I was able to dissassemble the blower motor. I used compressed air to blow out the carbon dust from the worn brushes. I oiled the bushings and the felt reservoirs surrounding the bushings. I reassembled the motor and laid it aside.

I removed the glovebox and the bottom half of the evaporator housing from inside the truck. There are two large screws that hold it to the firewall. Other than that, there are a bunch of clips that hold the two halves together. There are four across the back of the housing that you have to get "blind". I used a long, thin, flat screwdriver to pop them loose. You may not be able to get the back ones back in place afterward, but not to worry; the two large screws are plenty to hold it in place. The front clips are easy to put back.



I used a plastic basin to catch water as I hosed it out with the garden hose. I sprayed it with Castrol Super Clean, then rinsed it again.




I cleaned out the bottom housing and reinstalled everything.



With the vent control set for the upper vents, a strong blast of air was still blowing out of the lower vents. I simply plugged the lower vents with a clean pair of socks and the upper vents are blowing properly again. It's a redneck move, but I cannot justify removing the entire dash just to fix a faulty flap in the ducting.

I hooked up the gauges to the system and found that the charge was on the low end of the reccommeded charge. My system has a sight glass built into the accumulator. With the system running and stable, It was showing a lot of bubbles. It actually looked like it was foaming. That is a sure sign of an undercharged system.
Since I have had the truck for three years and it has always worked, I figure it has the right to be a little low on refrigerant. I suspect that it leaked out past the compressor seal over the years.
I topped it off with R12 until the bubbles went away and called it good.

What a difference! This system never worked this good in all the time I have had it. I should have checked it two years ago.

wow! I need to check mine too!

where you get the R-12? I need some of that stuff.

quote:

Originally posted by LordBiotree:
where you get the R-12? I need some of that stuff.

My late father bought a tank just before it required a licence to buy. I inherited it when he passed. It is highly cherished.