Stormin Mormon wrote:
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



One thing I should mention is that when I change
over a small system, (compressor burnout), I have
a couple of Q-size nitrogen cylinders and injectors
that I use to blow system flush through the tubing
and evaporator/condenser. If you get the right
compressor, you may not have a problem with the cap
tube when it comes to capacity if you go back with
R-134a. I personally like to use R-416a which will
sub for both R-12 and R-134a. The R-416a runs a lower
head pressure than R-12 and will work with either
oil. It is recommended to use alkylbenzene or POE oil
if you have an oil return problem but I've never had
problem using 3GS mineral oil in a system with R-416a.

TDD