Stormin Mormon wrote:
Last couple days, I've had the chance to work on a reach in
cooler, at a restaurant. Under a counter. The old guy who
runs the place says it needs freon every six months. The
aluminum evaporator gets wet, and probably has a lot of
pinhole leaks. I checked all the fittings, and find no leaks
at fittings or braze joints. Metering device is TXV, and the
system has a receiver.

The system is probably 30 plus years old. The evaporator is
above the compressor. About 8 inches higher, and maybe six
feet to the side.

Since the evaportator his higher, perhaps oil return isn't
an issue. Since it runs off a TXV, maybe it will adjust to
the lower heat capacity of 134a. Has anyone else tried such
a conversion? I'd much rather be feeding it 134a, compared
to some other gas or blend.


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. 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. 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. I've had very good luck with this
product:

http://tinyurl.com/otxsfg

TDD