I put UV dye in an old walk in cooler system.
When I shined my UV spotlight on the receiver,
the tiny pinhole leaks lit up like a starry
night sky. Replaced the receiver and no more
refrigerant loss.

CY: Also a very possible leak. I don't have a UV leak stuff
system, but maybe this is a good reason to consider one.
Used to have a bottle of red dye, for much the same reason.


I did change an old R-12
walk in cooler over to R-134a until I could
tear it down and pressure check every section
to find a leak. To change it over required
removing as much mineral oil as possible and
adding POE oil and refrigerant stop leak. The
system ran fine for a few years until the
owner decided to spend the money on a proper
tear down and leak hunt.

CY: In this case, that would mean unbrazing the compressor,
and unbraze the process stub. Tip out the mineral oil, and
pour in same volume of POE. I sense that's a bit of work.
Compressor change out typically takes me three hours. I
wonder if there would be enough oil return, with gravity, to
keep the oil out of the evaporator.


The R-12 expansion
valve was happy with R-134a and required no
tinkering. There was some fiddling with the
pressure switch but it was a pump down unit
with a solenoid valve controlled by the cooler
thermostat.

CY: I can imagine it would take a different pressure
setting. Probably down a couple pounds. But, that's
something I can set by the actual performance of the unit.
This unit controls temp with the pressure switch. No liquid
line solenoid.

I've had very good luck with this
product:

http://tinyurl.com/otxsfg

CY: Thanks. I've seen people mention that leak stop stuff.
Might work. I should try a can of it. Suggest it to the
restaurant guy.

TDD