Step 4—Discharge Solenoid Valve
Some larger units equipped with scroll compressors contain a
solenoid valve that is piped between the discharge tube and suction
tube of the compressor. The purpose of the solenoid valve is to
cause a rapid pressure equalization around the compressor, thus
reducing the normal shutdown sound created by reverse rotation of
the scroll. The solenoid valve is normally closed and is wired
across high-voltage line 1 to load terminals of the contactor. (See
Fig. 18.) The solenoid-valve assembly also requires a check valve
piped in the discharge tube between the solenoid-valve tee and the
condenser coil, or reversing valve on heat pumps. The purpose of
the check valve is to prevent refrigerant from bypassing through
the solenoid valve into the suction tube when the unit cycles off.
MILLENNIUM SCROLL COMPRESSOR
Step 1—Features
The scroll compressor pumps refrigerant through the system by the
interaction of a stationary and an orbiting scroll. (See Fig. 29.) The
scroll compressor has no dynamic suction or discharge valves, and
it is more tolerant of stresses caused by debris, liquid slugging, and
flooded starts. The Millennium scroll varies from the Copeland
scroll in that the Millennium has a shutdown flapper valve located
between the scroll plates and the discharge head, whereas the
Copeland has a check device at the discharge connection after the
discharge head. The Copeland discharge head unloads when the
compressor shuts down. The scroll plate actually runs backwards
while it unloads.A1to3second unloading of refrigerant occurs.
The Millennium flapper valve eliminates the refrigerant unloading
by not allowing the discharge head to run backwards because of its
location. The Millennium scroll compressor uses Zerol 150 oil
with 3 percent Syn-O-Ad and is the only oil recommended for oil
recharge. See Table 14 for recharge requirements.
Step 2—Compressor Protection
Millennium scroll compressors are protected by an internal line-
break mounted on the motor windings. Internal protectors respond
to overcurrent and high temperature. These protectors are
automatic-reset devices containing a snap-action, bi-metal switch.
Step 3—Troubleshooting
Troubleshooting mechanical and electrical problems in a scroll
compressor is similar to a reciprocating compressor, except that a
scroll compressor should never be allowed to pump into a vacuum.
The scroll compressor is capable of pumping into a vacuum very
quickly, which could cause fusite arcing and compressor failure.
See Step 4 of Reciprocating Compressor section for removal and
replacement.
Step 4—Scroll-Compressor, 3–Phase Monitor
CES0130075 — PHASE MONITOR
This control is factory-installed on all 3–phase, scroll-compressor
models. (See Fig. 31 and 32.) On start-up, the control will energize
the pilot relay for 2 seconds. The monitor will check for correct
compressor rotation. If rotation is correct, unit will continue to run.
If rotation is incorrect, the control will break the 24–vac power at
the contactor and an LED light on the control will flash. If LED is
flashing, turn off power, reverse L1 and L3 field-power leads, and
restart unit. This control will check incoming power at every
restart.
OLYMPIA SERIES HORIZONTAL UNITS
Step 1—General
This family of units has horizontal airflow which allows for greater
installation flexibility. The blow-through design of the coil, along
Table 14—Compressor Oil Recharge
COMPRESSOR MODEL
RECHARGE
(FL. OZ.)
OIL TYPE
Carlyle/Scroll
”J” Type 44 Suniso 3GS
SC, SRD450AC 34
Zerol 150
w/3 percent
Syn-O-Ad
SR 52
SRH482, SRY482 68
SRH602, SRY602 70
Copeland
CRG3, CRH3, CRJ3, CRK3, CRL3 51
Suniso 3GS
CRN5, CRP5, CRT5, CTH1, CTL1 66
CRC4, CRZ4 36
CR16K6 Through CR42K6 42
*ZR18K1 19
*ZR23K1, ZR28K1 24
*ZR34K1 30
*ZR40K1 34
*ZR49K1-PFV 56
*ZR49K2-TF5, ZR49K2-TFD 56
*ZR61K2-PFV 56
*ZR61K2-TF5, ZR61K2-TFD 66
Tecumseh
AV55 50
Suniso 3GSAW55 30
AG 60
Bristol
H23A 52
Suniso 3GS
H23B 37
H24A3, H24A4 47
H24A5 52
H25A, H26A 62
H25B, H26B, H29B 32
*Copeland scrolls are charged initially with Sontex 200LT white oil. Since this
oil is not commercially available, use 3GS.
Fig. 30—Location of Discharge Thermostat
A90198
PLASTIC CAP
PRONG
BLUE SEALANT
GROMMET
THERMAL GREASE
THERMOSTAT
29
To Next Page
Loading...
Need help?
General
