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.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..

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

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

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

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.

CY: Yes, that sounds wise. Get the acids out. Fortunately,
we're not at burnout, on this system. Yet.

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.

CY: The system I'm servicing has a receiver. So, in theory
it should feed liquid The metering device is TXV, so it's
got some kentucky windage, as to delivering refrigerant.

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.

CY: When it came out, I got some 409a. Supposed to drop
right in, to sub for 12. Problem is, you have to deliver
liquid. Either pump it into the liquid side, or flash it to
vapor before it gets to the compressor. Which, 409a, is
more expensive than 416a, I find out later. Didn't know you
could sub 416a for both of those. 134a is a bit cheaper than
416, I think. I'd love to load the beast up with a couple
pounds of R-22, I still have a bunch of that. But, the
pressures are a bit too high.

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.

CY: Good to know. Thanks. Ideally I'd like something like
134a so I can use vapor to charge the system. No risk of
slugging the compressor.

Stormin Mormon wrote:
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.

CY: Yes, that sounds wise. Get the acids out. Fortunately,
we're not at burnout, on this system. Yet.

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.

CY: The system I'm servicing has a receiver. So, in theory
it should feed liquid The metering device is TXV, so it's
got some kentucky windage, as to delivering refrigerant.

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.

CY: When it came out, I got some 409a. Supposed to drop
right in, to sub for 12. Problem is, you have to deliver
liquid. Either pump it into the liquid side, or flash it to
vapor before it gets to the compressor. Which, 409a, is
more expensive than 416a, I find out later. Didn't know you
could sub 416a for both of those. 134a is a bit cheaper than
416, I think. I'd love to load the beast up with a couple
pounds of R-22, I still have a bunch of that. But, the
pressures are a bit too high.

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.

CY: Good to know. Thanks. Ideally I'd like something like
134a so I can use vapor to charge the system. No risk of
slugging the compressor.


I have a couple of charging adapters that allow
liquid charging. One is a simple tiny orifice
that you can screw on anywhere on the low side
line or refrigerant cylinder. The other is about
the size of a small fist with expansion room.

http://tinyurl.com/otvo8s

http://tinyurl.com/qzm4es

TDD

well.....since you don't want to fix it right, you could try this: 1.
insult the customer. try a smart-ass answer to any questions he might
have. 2. Add any refrigerant that you want to, because on a system that
old, anything other than R-12 is probably going to put too much stress
on all parts of the system, leading to failure soon. 3. Insist on cash
payment, after all you wouldn't want to have to pay taxes on that 4.
Wish him a nice day, and give him some literature about the LDS church.
5. In about six months, wonder why he hasn't called you back out.

Would you suggest about 8 pounds of R-22 would be about
right?

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


wrote in message
...
well.....since you don't want to fix it right, you could try
this: 1.
insult the customer. try a smart-ass answer to any questions
he might
have. 2. Add any refrigerant that you want to, because on a
system that
old, anything other than R-12 is probably going to put too
much stress
on all parts of the system, leading to failure soon. 3.
Insist on cash
payment, after all you wouldn't want to have to pay taxes on
that 4.
Wish him a nice day, and give him some literature about the
LDS church.
5. In about six months, wonder why he hasn't called you back
out.