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Recharging Refrigerant

S

Steve@Advance

Well-known Member
The drink machine at work keeps icing up the coil.
There is no auto defrost system, there is no
reason to need defrosting since the setting is
always above freezing.

I'm assuming it's low on refrigerant.

It has a charge port, appears to have been added.
We've had this machine about 10 years, never added
any before, so it must be a very slow leak.

I've never tried to add to a system this small. It
only holds 8 ozs. If I connect the gauges, won't I
loose so much removing the connections it will
change the amount left in the system? There is
only a port on the low side anyway...

The tag says it uses R12. How can I tell if it
still has R12 or has been changed to 134? Should I
just start over with 134? What about the
compatibility with the oil?

I have 1 can of R12. Don't want to waste it!
Thinking about just connecting it with a simple
hose with a ball valve and giving it a guess...

Any ideas?

Thanks!
 
R-12 fittings and 134A fitting are different so if a small fitting and screw on R-12 if bigger and snap on 134A
 
8 oz is going to be a critical charge unit. Vacuum it down and use a charge cylinder or digital scale. You could guess like you would on a window shaker I reckon but it'll be risky.

You might want to clean the condenser coil and check the fan first before you open that can of worms.
 
The fitting on a can of 134a is different from r12, so you will need to buy an adaptor.

I have 40 year old dehumidifiers that leaked out all the r12. I pulled a vacuum and filled with 134a. They work fine. I also installed an old thermostat from westinghouse a/c on the suction line, so if the suction line frosts up it turns compressor off. I just wish I hadn't pitched so many of the frost controls.

Then I removed all the electrical controls from dehumidifiers and put them under water to look for leaks, found none. So my leaks are extremely small. So far, 6 months later,my 2 dehumidifiers are working just fine.

I look at it this way, anything using r12 is very old so if you get a few more years out of it using 134a I'm not going to worry about the oil. The unit is on borrowed time.
George
 
Icing is indeed an indicator of a low charge. If the tag says that R-12 is in the system, it is probably still using R-12. Small critical fill systems like this are generally sealed systems that rarely need service.

BUT... the only SURE way to tell which refrigerant is currently in the system is to have it analyzed. There are analyzers on the market that can tell you which refrigerant (or mixture of them) is present.

Since the capacity is so small, it would be critical to have the right amount in the system for proper function. Recover, vacuum, and recharge with an accurate measurement is the recommended course of action. Then you will know that it has the correct charge in it.
 
That sounds like a plan, vacuum it down and start over. I have a digital scale, so long as I don't move the hose or scale or touch anything while it's charging I could get somewhat close to the 8 oz. charge.

The condenser and evap are clean, the fans are working.
 
Think I'll vacuum it down and recharge with r12. I have a scale, just going to be tricky getting the hose off quick enough!
 
I'm thinking the r12 and 134 would interchange. Since I have a can of 12, might as well find it a good use before the can rusts out!

Next time, if it's still alive, I'll go to 134.

It is probably 40 years old, just hate to junk it, everything else works good. It's mechanical, I can work on it!
 
Hello Steve@Advanced

Here is what you do. After you have charged the system, push down on the hose. Then completely unscrew the fitting while pressing down. Tnen a quick removal should minimize the loss of refrigerant,

Guido.
 
(quoted from post at 12:45:40 06/24/14) Thanks, I'll try that!
Click to expand...
don't do all that dump charge/vacuum /etc. Just add a little refrigerant at a time until the suction pressure is about 35-38 degrees and after a few hours the ice will go away & your charge will be right with the world. Life really is simple sometimes.
 
I would add the r-12 to system a little at a time till suction pressure reaches approx. 20#.
If the suction frosts back to the compressor you have added to much. Will not hurt anything. Just let a little back out.
Fittings for 134a and r12 are the same on refrigerators and commercial walk-in units.
I work on these type units all the time.
Would not recommend using R-134A.
 
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