(Sorry I don't have the April issue out. The company
that mails this for me went down about a month ago and stayed down, and I
couldn't get it to you. The combined April/May issue will be out in the first
week of May)
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In this issue:
1) Refrigeration System
Recharging Basics, Part 2: Leak Testing
2) Over 2 Million Maytag Dishwashers Recalled
1) Thought we'd finally get
back to the subject of refrigeration systems this issue, so let's talk a little
bit about refrigerant leaks.
(Just a reminder here, we're
discussing small residential systems in this series, not commercial
refrigeration systems, which are very different critters from a service
As we talked about last time,
the frost pattern is the easiest diagnostic tool to use in determining whether a
refrigeration system is causing our trouble, or whether the problem lies
So if we're looking at an
evaporator coil that's only partially coated with frost and the compressor's
running, we know there's a 'system' problem, either a leak or restriction.
One good way to determine
which one of the two causes of a short pattern we have is to add a few ounces of
refrigerant (a 'diagnostic charge') while watching that frost pattern. If it
travels across the coil as we add refrigerant, we know it's definitely a 'leaker'.
If the pattern doesn't change, then it's restricted.
(We'll talk more about adding
refrigerant in an upcoming article).
Leaks are the more common of
the two problems, and there are several methods used to find them.
The first is to visually
inspect all tubing connections, starting in the compressor compartment. Oil
travels through the system along with refrigerant, so any oil around a soldered
or brazed tubing joint is a really good leak indicator.
Applying leak test 'bubble'
solution to the suspect spot will verify it pretty readily. The products sold
for this purpose are best, but a strong detergent and water mixture can be used
in a pinch, too.
When leak testing, we want to
ensure the area we're testing is under the highest internal pressure we can get,
to give us the highest flow out through the leak.
The way to get that, assuming
there's still some refrigerant left in the system (still some frost showing on
the evaporator), is by testing high side fittings with the compressor running,
but testing suspect low side leaks after it's been turned off for at least a few
The 'low side' includes the
evaporator coil in the freezer, and the suction line (the larger tube that
connects to it) all the way back down to the compressor. This part of a system
contains low pressure when the compressor's running, because it 'pulls' on this
side - not what we want for leak testing.
The 'high side' is all of the
rest of the tubing including the condenser (warm) coil and 'Yoder loop' inside
the cabinet. When testing for high side leaks, I like the compressor running
if possible, because it's 'pushing' pressure into this tubing and increasing
your chances of finding the leak quickly.
The most popular method of
leak testing these days is with an electronic leak detector. There are dozens of
these on the market, and they are terrific at locating low flow and in-cabinet
leaks. Less messy than smearing bubble solution all over, today's models are
very fast and sensitive, but can be pricey.
I'll be dating myself here,
but for many years, I used a Halide leak detector attached to a small acetylene
or propane torch. They are also very accurate when properly set, and use the
change in the color of a small flame to reveal the presence of refrigerant.
After realizing that cigarette smoke was interfering with my old 'first
generation' electronic detector, I went back to my 'old reliable' Halide torch
quite a few years.
A few old-fashioned but still effective leak
L to R, two bubble solutions, internal red dye, and a Halide torch
detector (flame color changes in presence of leaks)
Other leak detection methods
include both staining and fluorescent dyes, and even ultrasonic listening
devices. Many new refrigerators come with a small amount of fluorescent dye
already in the system. But most leaks can be found fairly easily with simple methods.
Well, I'd better stop there
for now. More next time.
2) Here's another appliance
recall I'd like to let you know about.
This one involves some 2.3
million Maytag and Jenn-Air dishwashers, made from July '97 thru June '01, and
it's one we want to get cleaned up pretty quickly.
The latest figures I have
report some 135 of these machines that have caught fire so far, and that scares
me - and you can bet it scares Maytag, too.
Here's a list of model
numbers that are recalled. Note that of these models, only those whose serial
numbers end in the SM thru YZ date code range are recalled.
AFFECTED MODEL NUMBERS
DWU9902AA, DWU9922AA, DWU9962AA, MDB3000AW,
MDB3100AW, MDB4000AW, MDB4010AW,
MDB4030AW, MDB4040AW, MDB4050AW, MDB4100AW, MDB4160AW, MDB4800AW, MDB5000AW,
MDB5100AW, MDB6000AW, MDB6100AW, MDB6160AW, MDB6800AW, MDB7000AW, MDB7100AW,
MDB7130AW, MDB7160AW, MDB8000AW, MDB9000AW, MDB9100AW, MDBD820AW, MDBD850AW,
MDBD880AW, MDC4000AW, MDC4100AW, MDB5100AW
JDB3010AW, JDB3910AW, JDB4950AW, JDB5900AW, JDB6900AW,
SERIAL CODE RANGE: SM-YZ
problem is caused when rinse agent leaks from its dispenser in the door, where
it can short-circuit internal wiring and ignite.
If you have one of the listed
models, call 800-675-0535 to register it. Maytag will send you the necessary
parts kit for your machine and put you in contact with a local authorized
servicer to do the work for you, all free of charge.
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May God richly bless you and
Dave’s Repair Service
New Albany, PA
‘Worry looks around, Sorry
Looks Back, Faith Looks UP’.
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