Refrigeration System Service; Dehydrating And Evacuating Refrigeration System; Leak Testing; Brazing - Amana PTAC Service Instructions Manual

SERVICING

REFRIGERATION SYSTEM SERVICE

WARNING
WARNING
BRAZING REQUIRES HIGH TEMPERATURES. TAKE
PRECAUTION TO PROTECT AGAINST PERSONAL
INJURY OR PROPERTY DAMAGE. TO AVOID THE
RISK OF FIRE, THE REFRIGERATION SYSTEM MUST
BE KEPT FREE FROM CONTAMINATION DUE TO THE
PRESENCE OF AIR. FOLLOW THESE INSTRUCTIONS
EXACTLY. TO AVOID THE RISK OF BURNS,
PROPERTY DAMAGE, PERSONAL INJURY OR DEATH,
DO NOT PLUG IN THIS PRODUCT OR APPLY POWER
TO THE COMPRESSOR IF THE COMPRESSOR
TERMINAL COVER HAS BEEN REMOVED OR IS NOT
FIRMLY IN PLACE.
IMPORTANT NOTE: Effective July 1,1992 before opening
any refrigerant system it is the responsibility of the service
technician to capture the refrigerant for safe disposal.
Refer to the cooling and heater performance charts in this
section for capacity test procedure.
A step-by-step procedure for determining source of trouble,
suggested method and normal values are provided in the
Diagnosis Charts.
Service operations requiring opening of the hermetically
sealed refrigeration system should not be performed in the
home. The unit must be taken to a well equipped shop
where special equipment for evacuating, dehydrating, charg-
ing and testing is available. The following equipment is
necessary.
Equipment to use dry nitrogen of no more than .0012 grains
of moisture. Vacuum pump capable of evacuating to a mini-
mum of 50 microns.
Vacuum Pump - Kenney or equivalent. Micron gauge to check
vacuum. Refrigerant charging cylinder accurate to within
1/4 oz. Electronic leak detector - General Electric or equiva-
lent. Electrical equipment to test: compressors, capacitors,
voltage relays and overload protectors Electrical test board
or portable equipment, including: volt meter, ammeter, and
watt meter. Silver soldering and brazing equipment: Pinch
off tools 1/4" to 5/8" Thermocouple tester.

Dehydrating And Evacuating Refrigeration System

A rather popular misconception exists that since air condi-
tioners normally operate with a refrigerant temperature
above 32°F., moisture in the system is harmless. Nothing
could be further from the truth. Oxygen from moisture plus
normal compressor and motor heat reacts chemically with
the refrigerant and oil to form corrosive hydrochloric and
hydrofluoric acids. These acids contribute to the break-
down of motor winding insulation and the corrosion of com-
pressor working parts and cause unnecessary compressor
failure. Sludge, which is a residue of the chemical action,
coats all compressor parts, the inside of refrigerant tubing,
and may even restrict refrigerant flow through the capillary
tube(s).

Leak Testing

Refrigerant leaks are best detected with a halide or elec-
tronic leak detector.
NOTE: Leak detectors must be compatible with R-410A re-
frigerant.
The importance of careful leak testing cannot be overem-
phasized. Undetected leaks invariably lead to repeated calls
and eventually result in system contamination, restrictions
and burned out compressors.
For a system that contains a refrigerant charge and is sus-
pected of having a leak, stop the operation, check all tub-
ing and fittings. Soap suds may also be used.
NOTE: The flame of the halide detector will glow green in
the presence of R-410A refrigerant.
If a leak is detected, do not attempt to apply more brazing
material to the joint. Recover the charge, unbraze the joint,
clean and rebraze.
For a system that has been newly repaired and does not
contain a charge, connect a cylinder of refrigerant, through
a gauge manifold, to the process tube of the compressor
and liquid line strainer. Open the valve on the cylinder and
manifold and allow the pressure to build up within the sys-
tem. Check for and handle leaks as described above.
After the test has been completed, recover the test charge,
evacuate the system, and recharge with clean refrigerant.

Brazing

Satisfactory results require cleanliness, experience and the
use of proper material and equipment.
The connections to be brazed must be properly sized, free
of rough edges and clean.
The generally accepted materials are:
SIL-FOS (Alloy of 15% silver, 80% copper, 5% phosphorus) is
used without flux on copper to copper. DO NOT USE FOR A
COPPER TO STEEL CONNECTION. Recommended heat is
approximately 1400°F.
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