Determining Amount of Freon in Machine

[ZMonet]

I have R12 gauges and I was wondering if there is any way to use the gauges to determine the amount of freon (under or overcharged) in the machine?  I also purchased this $10 home/auto gauge that was supposed to tell me the freon level (low/normal/caution/danger) but it didn't seem to work with the soda machine (couldn't get it to connect).  Any help appreciated.

[globalcompressors]

Is it the single gauge and hose set up? The dial green, yellow, red, etc? It's probably one used for automotive with a 134a snap on
connector on the end of the hose, kind of like an air hose fittling?

You need a set of gauges, blue and red, manifold, and 3 hoses.
Use a clamp on, tap valve, screw the hose to it and read the pressure. A decent set runs around $100 or so.

Eric

[ZMonet]

Thanks Eric.  This is an old R12 gauge.  It has the three hoses.  Will reading the pressure tell me if it under or overcharged?  On my machine I only see the low-side connection, not the high.  Can I do the reading just off the low?  Thanks Eric (or anyone else).

[globalcompressors]

Yes,

Those will work...Low side is what you're after. Loose rule of thumb, running, cold machine, 5-10 psi. Hot machine, running
compressor, 30-40 psi. Hot machine, non-running, static 80 psi.

Hope this helps. That's about the best I can do without starting
a refrigeration school. Good Luck!

Eric

[ZMonet]

I'm sure I'm missing something.  I tried hooking up the blue hose to the low side and let it run and got no reading.  I tried turning the valve openers on the blue gauges, but still got no reading.  I then tried to do the same with the red hose and still got no reading.  Am I doing something wrong here?  I suppose it is possible the gauges don't work, but I think it is more likely I'm the culprit.  Is it possible that the low side valve isn't functioning properly?  Does this happen?  Any help appreciated.  My 1000 words...

[FDNY1975]

This type of service valve needs to be opened up to get a reading on the gauge. Take off the cap you see just above where you put your hose under it is a service valve. If you don't have a service wrench that can be bought at any local refrigeration supply store you can open it with an adjustible wrench just be carefull not to strip it. You will then get a reading on you gage and be able to add freon just remenber to close it again before you disconect the hose.

[ZMonet]

Thanks FDNY.  I got the cap off, but I want to make sure I'm opening it up correctly.  I assume I should hook up the hose prior to turning the stem.  Then, how many times will I need to turn the stem before I turn it on?  The problem is that it is difficult to get to the stem with the machine on because the fan is going.  Will I get a reading instantly or do I need to wait for pressure to build up or something?  Finally, if I undid the gauge hose before properly closing the stem, would what freon is in there escape?  Thanks again.  Sorry for the 50 questions, but I feel like I'm close...

[johnieG]

1: Turn machine OFF, wear safety glasses & wear gloves!

2: Connect Gauge sets' blue hose to the service port fitting shown. make sure all of your gauge-sets valves are "off" otherwise you'll leak freon out of the yellow or red hose!

3: turn the valve counter clockwise about 4-5 full turns. note that this "unscrews/raises" the service valve open & exposes the service port to the inside system pressure.

4: Take a note of what the "resting" pressure is, & now turn the machine on, & watch the pressure reading on the blue hoses (low-side/left Gauge).

5: reverse the above after you're done recording the pressures.   note that before you detach the blue hose from the fitting/port, you should close the service valve clockwise (as viewed from above) so that it "lowers" the service valve back down to seal off the service port, snuggly, do not go gorilla on it!

when removing the blue hose be carefull of freon escaping it can cause frost-bite, wear gloves! oh & no smoking! (burned freon is poison!)

now your getting somewhere.

[ZMonet]

lol....Thanks JohnieG for the detailed instructions.  I'm off on a 410 mile roadtrip to pick up my 7UP Slider and my U-Select-It, but this info will give me something to look forward to/think about on the trip.

[ZMonet]

I tried following JohnieG's directions...I hooked everything up, but got no reading on the gauge.  When I turned it on, I also got no reading.  When I turned the nob on the gauges freon gas started coming out (quickly closed).  I then tightened the service valve back down.  When I took off the gauge connector a little gas came out and a couple drops of oil.

Is it likely that the gauges aren't working, or could it be something else?