how can you tell what refrigerant is in a system that has somehow had its nameplate defaced or removed? Temperature and pressures for R-12, R-134a and R-409a are very close and I am not convinced a pressure reading compared with temperature could definitively identify the refrigerant.
Is there any mod.#'s on the compressor or the skid?
Always check your metering device, if it is like a labeled TX valve.
Next collect the numbers from your compressor, if available. If you carry the book on your truck lesting what the numbers mean, then you have the start for categorizing the pressure range of the refrigerant as well as the temperature range of the gas.
As well as the physical elements of the box being cooled.
You can firgure since it is a freezer, it will be using one of several types of refrigerants.
Let's break this down.
It may be MP66. But that would mean you had to have an older R-12 compressor. It would mean your TX valves would be labeled R-12 on them.
This would add up to an MP66 charge being the most likely gas in the system as of this date.
Another freezer; this one has an R-22 TX valve.
That would mean it is probably R-22. Duh?!
But how about if the valve has one of those sticker labels with several colors on the powerhead?
It could be any of several refrigerants.
If the charge is small enough, it may be cost effective to recover, replace the drier and recharge with what you beleive the best refrigerant is for that application.
If the powr head label is purple, then you have either R-502 in there... or it has been topped off and or replaced by the drop in replacement. And not R-404.
Hope this helps. Sometimes there's simply nothing to do but to pull it out and put in what you can label as being the gas your sure of.
Whatever you end up doing, always leave the system labeled if you added freon. And be liberal with your Sharpie!
Unless your supply house or some other place nearby has a refrigerant analyzer, this is all you can do and be assured as to what is in the system.
Originally posted by R12rules
Sometimes there's simply nothing to do but to pull it out and put in what you can label as being the gas your sure of.
When in doubt, pull it out.
I use a Sharpie marking pen for indoor work, but any outdoor stuff calls for a more permanent paint marker......Sharpie's will fade away in sunlight after about a year or so.
Ice, I'm with you!!!
I got two styles of outdoor markers like the one's junk yards use for auto parts.
They last quite a while outdoors.
But I like to do most of my marking where the sun dont shine.
The evap coil near the TX valve cover.
The compressor label itself, if it's white.
Or near the contactor if it has a large electrical panel.
Then also on the filter drier. I mark that too.
Those markers for outdoor use are sold thru welding supplies.
Tough one the tell the customer...There is no easy way to tell what someone has put into the system. If you know what the base product was ( R-12 or 502) then you have to pull the old refrigerant, change the drier, pull a vacuum add your own refrigerant. Make sure you lable the system properly so when I come back the next time I don't have to do the same thing.
If you don't know what the base is then check txv heads and/or compressor model number. Then go from there.
labeling is cheaper than retro-fits....