Checking Freon Level
 

I suspected my 88 was low on R12 so decided to add some but I have a question about the site glass. Before I added anything it appeared to be clear w/ ac on and running at 2k rpms and the small ball stayed at the bottom. I hooked up the freon and had my gf keep it at 2k rpms. The freon can got VERY cold and the a/c is now running about 15 degrees cooler at the vent. (Previously saw 70 w/ ambient temp low 90's, now seeing upper 50s at vent, same amb. temp) The site glass looks exactly the same...totally clear and little bead/ball at bottom. Is it possibly still low? About how long should a system take to take in a can of R12? I ran it about 5 minutes and the bottom 2" of the freon can was ICE cold with frozen condensation on outside.
Thanks,

How big was the can of R12? I believe your car holds about 40oz total.

...Bruce

It was a 12 oz can but the system was far from being empty. I'm just curious as to what I should have seen on the site glass and if maybe I should have kept the can on the car longer. It's sealed up so I can add more freon if that's what's needed.

As far as I know you should see the ball floating in the middle of the sight glass. You can also get a pressure gauge and check the system pressure at the compressor to get a better idea of how much freon you have.

...Bruce

I've never trusted the "sight glass" on any car, much better to check pressures or, even better yet, monitor temp. at the vent; add coolant unitil you see temperatures in the mid to high 40's at the center vent with the fan at 1/2 speed, that's probably as good as you'll ever get with the stock system. BTW, if the system is close to fully charged it can take 10-15 minutes (or more) to empty a can of R12, then you should let the engine run (or better yet drive it) for 20-30 minutes to let the system equalize. Then check the temp. at the vent. BTW, where did you get a can of R12? I'm still hoarding my last one.

One last thing, if you over-fill the system you'll start losing cooling capacity.

Good luck,

Jerry M
'78 SC