The single biggest killer of gas refrigerator cooling units is
corrosion. The common misconception is that it's the rust on the
exposed pipe at the bottom of the cooling unit (down by the burner) that causes
the leaks. In fact, this is rarely the case. The rust often seen on the exposed
pipes is largely superficial even though it may look terrible. In gas
refrigerator cooling units, the worst corrosion always occurs on the evaporator
piping (the pipes that get cold) because they are physically located inside the
refrigerator cabinet (right behind the back wall of the interior) and is covered
by insulation. While the refrigerator is running, moist air finds its way to the
cold evaporator pipes and condenses on the surface. Since the evaporator pipes
are encased, the condensed water cannot readily drain away and therefore is held
next to the steel pipe. After several years rust develops.
The rusting is accelerated when the refrigerator is turned off for the season,
allowing the evaporator to warm up. The rusting eventually progresses to a point
where severe pitting occurs in the surface of the steel. These pits eventually
extend all the way through the pipe wall into the inner space of the pipes. The
result is a leak.
You will usually, but not always, smell the leak when it occurs. If the leak
does occur on the outside piping, you probably won't smell it. Sometimes, even
if the leak is on the inside, you may not smell it if mostly hydrogen is leaking
out. Most of the time, however, you will know that your refrigerator is leaking
because of the pungent ammonia smell coming from inside your cabinet.
After your refrigerator starts leaking, it will eventually (usually very soon)
stop cooling. The worst thing you could do at this point is to delay getting
your refrigerator repaired because corrosive ammonia is eating away at the
cooling unit steel (ammonia doesn't corrode the steel while it's inside the
cooling unit because of the rust inhibitor inside). The longer you delay
getting your refrigerator's cooling unit rebuilt, the lower the odds are of a
successful and reliable repair. Also the ammonia gas will eat up the inside of
the cabinet and the parts. The light and thermostat will need to be replaced if
left too long and the inside plastic will turn yellow. You can see why removing
all rust from the cooling unit by sand blasting and rust proofing the cooling
unit are essential steps in a proper cooling unit repair. Just as with your car,
if you don't remove the rust, it'll just come back and, after another season or
two of use, the cooling unit will fail again.
