Servicing - Maytag Amana PTC A Series 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 sec-
tion for capacity test procedure.
A step-by-step procedure for determining source of trouble,
suggested method and normal values are provided in the Diag-
nosis 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 equip-
ment for evacuating, dehydrating, charging and testing is avail-
able. 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 minimum
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 equivalent.
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 condition-
ers 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 ac-
ids contribute to the breakdown of motor winding insulation
and the corrosion of compressor working parts and cause un-
necessary 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 electronic
leak detector.
The importance of careful leak testing cannot be overempha-
sized. 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 tubing
and fittings. Soap suds may also be used.
NOTE: The flame of the halide detector will glow green in the
presence of R22 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 con-
tain 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 system. 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.
SILVER SOLDER (Alloy of 30% silver, 38% copper, 32% zinc.)
is used with fluoride base flux on copper to steel, brass to
copper, steel to steel, brass to steel. Recommended heat is
approximately 1200°F.
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