Friedrich SM21L30-A, Service Manual

Page: 11 / 36

11
EQUIPMENT REQUIRED
1. Voltmeter
2. Ammeter
3. Ohmmeter
4. E.P.A. Approved Refrigerant Recovery System.
5. Vacuum Pump (capable of 200 microns or less vacuum.)
6. Acetylene Welder
7. Electronic Halogen Leak Detector (G.E. Type H-6 or
equivalent.)
8. Accurate refrigerant charge measuring device such as:
a. Balance Scales - 1/2 oz. accuracy
b. Charging Board - 1/2 oz. accuracy
9. High Pressure Gauge - (0 - 400 lbs.)
10. Low Pressure Gauge - (30 - 150 lbs.)
11. Vacuum Gauge - (0 - 1000 microns)
EQUIPMENT MUST BE CAPABLE OF:
1. Recovery CFC’s as low as 5%.
2. Evacuation from both the high side and low side of the
system simultaneously.
3. Introducing refrigerant charge into high side of the
system.
4. Accurately weighing the refrigerant charge actually
introduced into the system.
5. Facilities for fl owing nitrogen through refrigeration
tubing during all brazing processes.
HERMETIC COMPONENT REPLACEMENT
The following procedure applies when replacing components
in the sealed refrigeration circuit or repairing refrigerant
leaks. (Compressor, condenser, evaporator, capillary tube,
refrigerant leaks, etc.)
1. Recover the refrigerant from the system at the process
tube located on the high side of the system by installing
a line tap on the process tube. Apply gauge from
process tube to EPA approved gauges from process
tube to EPA approved recovery system. Recover
CFC’s in system to at least 5%.
2. Cut the process tube below pinch off on the suction
side of the compressor.
3. Connect the line from the nitrogen tank to the suction
process tube.
4. Drift dry nitrogen through the system and un-solder
the more distant connection fi rst. (Filter drier, high side
process tube, etc.)
5. Replace inoperative component, and always install a
new fi lter drier. Drift dry nitrogen through the system
when making these connections.
HERMETIC COMPONENT REPLACEMENT cont’d
6. Pressurize system to 30 PSIG with proper refrigerant and
boost refrigerant pressure to 150 PSIG with dry nitrogen.
7. Leak test complete system with electric halogen leak
detector, correcting any leaks found.
8. Reduce the system to zero gauge pressure.
9. Connect vacuum pump to high side and low side of
system with deep vacuum hoses, or copper tubing.
(Do not use regular hoses.)
10. Evacuate system to maximum absolute holding
pressure of 200 microns or less. NOTE: This
process can be accelerated by use of heat lamps,
or by breaking the vacuum with refrigerant or dry
nitrogen at 5,000 microns. Pressure system to 5
PSIG and leave in system a minimum of 10 minutes.
Release refrigerant, and proceed with evacuation of
a pressure of 200 microns or less.
11. Break vacuum by charging system from the high side
with the correct amount of liquid refrigerant specifi ed.
This will prevent boiling the oil out of the crankcase,
and damage to the compressor due to over heating.
NOTE: If the entire charge will not enter the high side, allow
the remainder to enter the low side in small increments while
operating the unit.
12. Restart unit several times after allowing pressures
to stabilize. Pinch off process tubes, cut and solder
the ends. Remove pinch off tool, and leak check the
process tube ends.
SPECIAL PROCEDURE IN THE CASE OF COMPRESSOR
MOTOR BURNOUT
1. Recover all refrigerant and oil from the system.
2. Remove compressor, capillary tube and fi lter drier from
the system.
3. Flush evaporator condenser and all connecting
tubing with dry nitrogen or equivalent, to remove
all contamination from system. Inspect suction and
discharge line for carbon deposits. Remove and clean
if necessary.
4. Reassemble the system, including new drier strainer
and capillary tube.
5. Proceed with processing as outlined under hermetic
component replacement.
ROTARY COMPRESSOR SPECIAL TROUBLESHOOTING
AND SERVICE
Basically, troubleshooting and servicing rotary compressors
is the same as on the reciprocating compressor with only
one main exception:
NEVER, under any circumstances, charge a rotary
compressor through the LOW side. Doing so would
cause permanent damage to the new compressor.