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2. Brazing
WARNING
1. R-404A itself is not ammable at atmospheric pressure and temperatures up
to 176°F (80°C).
. R-404A itself is not explosive or poisonous. However, when exposed to
high temperatures (open ames), R-404A can be decomposed to form
hydrouoric acid and carbonyl uoride both of which are hazardous.
3. Do not use silver alloy or copper alloy containing arsenic.
4. Use an electronic leak detector or soap bubbles to check for leaks. Add a
trace of refrigerant to the system (if using an electronic leak detector), and
then raise the pressure using nitrogen gas (140 PSIG). DO NOT use R-404A
as a mixture with pressurized air for leak testing.
1) Braze all ttings while purging with nitrogen gas owing at a pressure of 3 to 4 PSIG.
CAUTION
1. Always install a new drier every time the sealed refrigeration system is
opened.
. Do not replace the drier until after all other repair or replacement has been
made. Install the new drier with the arrow on the drier in the direction of the
refrigerant ow.
3. When brazing, protect the drier by using a wet cloth to prevent the drier from
overheating. Do not allow the drier to exceed 50°F (11°C).
) Use an electronic leak detector or soap bubbles to check for leaks. Add a trace of
refrigerant to the system (if using an electronic leak detector), and then raise the
pressure using nitrogen gas (140 PSIG). DO NOT use R-404A as a mixture with
pressurized air for leak testing.
3. Evacuation and Recharge (R-404A) (except MLH model)
1) Attach a vacuum pump to the system. Be sure to connect charging hoses to both high
and low-side access valves.
IMPORTANT
The vacuum level and vacuum pump may be the same as those for current
refrigerants. However, the rubber hose and gauge manifold to be used for
evacuation and refrigerant charge should be exclusively for POE oils.
) Turn on the vacuum pump. Never allow the oil in the vacuum pump to ow backwards.
3) Allow the vacuum pump to pull down to a 9.9" Hg vacuum. Evacuating period depends
on pump capacity.
4) Close the low-side valve and high-side valve on the gauge manifold.