I got to use my AC this morning for the first time on a small trip . I have converted from a non factory AC-ed car to factory AC. After two cans of 134A I am getting 46* out of the vents with 90 degrees outside. . I am undecided about adding the third can of 134A. It is working so good now I am thinking about leaving it alone.

Whats your vent temperature running

Joe Crawford
Texas

Hey Joe,

I put 2.5 cans in my rebuilt system and get 40* air from the vents. I made sure that I had 40psi on the low side. Starting on the same project in an 88 Formula today. Hoep it works as well as the last....

Pat

Regardless of what your air temp is, the system was designed to hold a certain amount of refrigerant. Refrigerant helps to cool the compressor so you need to make sure you have the right amount in there.

quote Originally posted by josef644: 134A I am getting 46* out of the vents with 90 degrees outside. .

46* duct temp is ideal for a GM system of that era even on R12. The preasure switch cycles on at 46 psi. On R12 the low side psi is almost the same as the temp at the evaporator core temp. The core temp is higher on R134A. Then there is the efficiency loss transfering from the core temp to the air temp. Mixing 90* ambient air with 40* core temp generally makes about 50* duct temp. You have done great already. Overfilling a system does not make it colder, it makes it warmer.

Most of what you said was "Greek" to me. My car is an 86 4cyl. It has the V5 compressor with the cycling switch installed in to the side of it. The V5's don't have a "cycling" switch on the accumulator. As I understand it the head pressure is what determines how hard it is working to arrive at a "predetermined" pressure for best performance.

My friend that put in the two cans said that it would need almost a 3rd can. He had a chart and also used 80% calculation to come up with the " almost three 12 oz cans". He had gauges. I just have a "add a can hose", with no gauge.

We stopped filling because the belt started screaming. It was to hot to climb underneath and tighten the belt. Remember the compressor is just above the cat converter and muffler. I just waited till I got home and let it cool down overnight to adjust the belt. I drove it 60 miles today . The belt never screamed any more.

I know that when my home AC freon got low the evaperator iced up. I don't want to ice the one in my car.

I also forgot to install the "drip cup" underneath the evaporator. I had water everywhere in the spare tire well. That will be a real fun job to put in. I love working upside down.

[This message has been edited by josef644 (edited 07-27-2008).]

i use the 90% method.
so by my method you would need 36 ounces.

I'd get a set of gauges on there before you add any more R134. The 2.5 cans is a good ballpark and your vent temps are good but you have no idea where the high pressure side is and adding more R134 is a blind shot.

With a V5 compressor pressure does not tell you all that much. The displacement constantly changes, so the pressure is not a good reflection of charge. The only way to accurately verify charge levels is the start from empty and monitor how much you have added. 80-85% of the R12 charge is a good number to use on all conversions.

quote Originally posted by Electrathon: With a V5 compressor pressure does not tell you all that much. The displacement constantly changes, so the pressure is not a good reflection of charge. The only way to accurately verify charge levels is the start from empty and monitor how much you have added. 80-85% of the R12 charge is a good number to use on all conversions.

Ok , we installed a new dryer and orfice tube. 4 oz of oil in the dryer. Had put 4 oz in the rebuilt V5 compressor. Then we started off empty with a 30 min vacume. Waited till after lunch ,(about 40 mins), and the needle was still holding. That is when we added the 134A. Then the belt squeeled and we stopped. When I turned the AC back on, it would run about 30-40 seconds till the belt squeel came back. After 3 or 4 times we gave up for the day. It was fine today after I tightened the belt last week. I didn't get to mess with it again till this morning.

It was 102 on the shade here at 330 pm this afternoon.
Joe Crawford

[This message has been edited by josef644 (edited 07-27-2008).]

Let us know how it works.

[This message has been edited by TK (edited 07-27-2008).]

The reason why preasures do not help that much on a variable compressor is that the displacement constantly changes, thus adjusting the preasure. Depending on ambient temp, 1.5 lbs and 2.5 lbs can have the exact preasure readings, or it may have differant readings. There are a few tricks that force the compressor to full displacement, then you can use preasure readings. It is not even close to being as accurate as starting from empty and filling the proper volume though.

quote Originally posted by TK: Let us know how it works.

Will do

40º on mine. once in a while it will hit 38º after a quick rain shower.

I cant get the "add a can" connector to work. its about 10years old. I was gonna put in about half a 12 oz can. I'm gonna have to take it to some one with a good hose end. Maybe Friday. I have mowing scheduled for the rest of the week.
Joe

Cold!

Mine runs about 46 degrees on a 90 degree day. I'm not complaining.

quote Originally posted by Cooter: Cold!

Showoff.

Are you running propane?

quote Originally posted by Cooter: Cold!

134a. I cheated- it was only about 90 when I checked the temp, but the car was sitting, so at highway speeds, it might get cooler

This is with a Caddy compressor- I don't know what kind it is, whatever comes on an '88 ElDorado. I had to back off the low pressure switch a little because it cycled too often. THe low side pressure is probably somewhere around 25 PSI at the temp shown above.

[This message has been edited by Cooter (edited 07-28-2008).]

Holy Sheep that is good. My wifes 2002 Elantra puts out 38 at about 60 mph. I don't remember the outside temperature, I am in Texas so it was somewhere around 95. Give or take a few.
Joe Crawford
Texsa

The last I checked my vent temp was 113ºF but the last I checked the internals inside my compressor were still in pieces. Still have a charge though.

quote Originally posted by DIY_Stu: The last I checked my vent temp was 113ºF but the last I checked the internals inside my compressor were still in pieces. Still have a charge though.

So are you saying when the belt squeeled and such your compressor was imploding? Very interested. Hve to do this stuff soon.

quote Originally posted by sjmaye: So are you saying when the belt squeeled and such your compressor was imploding? Very interested. Hve to do this stuff soon.

No It was a new belt and had streched a bit since I had put it on the car. I had about 5000 miles on the car. Belt squeel.