Well MY refrigerant guy told me the opposite and since he's been in the business for 35 years I tend to believe him.

No need to appologize to me. I could be wrong and I frequently am. I do know however that the more you put in the further back up the line you'll have liquid on the high side. If you get liquid back into the compressor it can break it.

I've been told by more than one tech that in a converted system you need to put a little less R134a in than the system would take of R12 because it doesn't have the same evaporation temps/pressures.

When the liquid evaporates after passing through the expansion valve is where it cools. If you have to much pressure on the low side it doesn't evaporate as fast and doesn't cool as well.

Edwin

 

i taped a digital thermometer to the suction line and gassed it until it got as cold as it was going to then gassed it untill it started warming up. then i removed the 134 till it got back down to the coldest point and left it there. there are bubbles in the site glass.

 

I was told to charge them just to the point of no bubbles but that's with R12 so your method is most likely a very good one.

Also if you buy your stock of R134a in the winter you'll get it a lot cheaper.

Edwin

 

Well i have mine totaly wrong. I have absolutely no bubbles at all. We got 1" of snow last night, so after it melts I will try that!

 

WHY? Ain't you cool enough?

 

My ac went out a few years ago...I think this will be year that I fix it.

 

I am SOOO glad I bought that 30# tin of R12 years ago.

 

You have yourself a gold mine now...
A 30# drum of real R-12 cost in the neighborhood of $1,300.00 now.
I have a stash also.
When you use R-12 you need to clear the sight glass for a full charge, but when you use R-134 or most of the drop-in's you only fill to 80% so it will be over charged if the sight glass is full.
R-12 is still available and all of the AC shops here still recharge with it on a virgin system.
On my retrofits I use Hot Shot from Icor and it seems to work the closest to R-12 and a lot better than R-134A
http://www.icorinternational.com/hotshot_opening.html#
Also have my own HVAC equipment vac. pump, digital scale, leak detector and EPA license because you need that to buy referent here.
Jim

 

Jim, you continue to be the MAN!

 

Hey Jim, do you happen to know the glide on HotShot?

 

Being in the HVAC&R field, I often have the work of reclaiming R12 so as to fix a leak and upgrade to HotShot. That coupled with my freon recycler/cleaner thing (brings pure gas back up to "As New" standard) and I'm set for a while.

 

What do you mean? I think I am missing something here?
Jim

 

What brand of recycler do you have?
Can you change tanks if you have to clean a burn out so you don't contaminate your booty?
I have a small Robinair I got about 8 years ago that is small enough to take on a roof or up a ladder and my vacuum pump is an Edwards industrial unit made in England It is certified to 2 microns It was originally from an electron microscope It is a bit overkill but the price was right. I also have an old belt driven Welsh vacuum pump.
Do you work on stationary or mobile units?
I used to work on some of the units in the big transit busses for LA County and they took 45# of R-22. The units were rated at 30 tons and the cold air had to be tempered through the heat exchanger or it could freeze the passengers solid. The compressors were 5 cylinder Trane units and either v-drive from the engine or they had a separate 4 cylinder Perkins or Kiki diesel driver.
This was back when the practice of recovering freon was to crack a line and let it out.
How did I get here?
Jim

 

I have a 90. Where is the site glass? Or does it have one?

 

The sight glass should be on the top of the reciever/ dryer, round canister on the passenger side fender above your air box. the window is only about 1/4" dia. and might be covered with crud.