2 | © Danfoss | DCS (CC) | 2018.06
8510284P01C - FRCC.PI.048.A3.02
Danfoss can accept no responsibility for possible errors in catalogues, brochures and other printed material. Danfoss reserves the right to alter its products without notice. This
also applies to products already on order provided that such alterations can be made without subsequential changes being necessary in specifications already agreed. All trade-
marks in this material are property of the respective companies. Danfoss and the Danfoss logotype are trademarks of Danfoss A/S. All rights reserved.
Danfoss A/S
6430 Nordborg
Denmark
1 – Introduction
These instructions pertain to the MLZ scroll com-
pressors used for refrigeration systems. They provide
necessary information regarding safety and proper
usage of this product.
2 – Handling and storage
• Handle the compressor with care. Use the dedi-
cated handles in the packaging. Use the compres-
sor lifting lug and use appropriate and safe lifting
equipment.
• Store and transport the compressor in an upright posi-
tion.
• Store the compressor between -35°C and 70°C /
-31°F and 158°F.
• Don’t expose the compressor and the packag-
ing to rain or corrosive atmosphere.
3 – Safety measures before assembly
Never use the compressor in a flammable atmosphere.
• Mount the compressor on a horizontal flat sur-
face with less than 7° slope.
• Verify that the power supply corresponds to the com-
pressor motor characteristics (see nameplate).
• When installing a compressor for R404A, R507
R407A, R407F, R448A/R449A, R513A, R452A or
R134a, use equipment specifically reserved for
HFC refrigerants which was never used for CFC
or HCFC refrigerants.
•
Use clean and dehydrated refrigeration-grade
copper tubes and silver alloy brazing material.
• Use clean and dehydrated system components.
• The piping connected to the compressor must
be flexible in 3 dimensions to dampen vibra-
tions.
• The compressor must always be mounted with
the rubber grommets supplied with the com-
pressor.
4 – Assembly
•
Slowly release the nitrogen holding charge
through discharge and suction ports.
• Connect the compressor to the system as soon as pos-
sible to avoid oil contamination from ambient moisture.
• Avoid material entering into the system while
cutting tubes. Never drill holes where burrs can-
not be removed.
•
Braze with great care using state-of-the-art
technique and vent piping with nitrogen gas
flow.
• Connect the required safety and control de-
vices. When the schrader port, if any, is used for
this, remove the internal valve.
5 – Leak detection
Never pressurize the circuit with oxygen or dry
air. This could cause fire or explosion.
• Do not use leak detection dye.
• Perform a leak detection test on the complete system.
• The low side test pressure must not exceed 31
bar /450 psi.
• When a leak is discovered, repair the leak and
repeat the leak detection.
6 – Vacuum dehydration
• Never use the compressor to evacuate the system.
• Connect a vacuum pump to both the LP & HP sides.
•
Pull down the system under a vacuum of
500 µm Hg (0.67 mbar) / 0.02 inch Hg absolute.
• Do not use a megohmmeter nor apply power to
the compressor while it is under vacuum as this
may cause internal damage.
7 – Electrical connections
• Switch off and isolate the main power supply.
• All electrical components must be selected as
per local standards and compressor require-
ments.
• Refer to electrical connections details. For three
phase applications, the terminals are labeled T1,
T2, and T3. For single-phase applications the ter-
minals are labeled C (common), S (start), and R
(run).
• Danfoss scroll compressors will only compress
gas while rotating counter-clockwise (when
viewed from the compressor top). Since single-
phase motors will start and run in only one di-
rection, reverse rotation is not a major consid-
eration. Three-phase motors, however, will start
and run in either direction, depending on the
phase angles of the supplied power. Care must
be taken during installation to ensure that the
compressor operates in the correct direction.
• Use ø 4.8 mm / #10 - 32 screws and ¼” ring terminals
for the power connection with ring connect screw
terminal (C type). Fasten with 3 Nm torque.
• Use ø 6.3 mm tabs for quick connect spade ter-
minals (P type).
• Use a self tapping screw to connect the com-
pressor to earth.
8 – Filling the system
• Keep the compressor switched off.
• Keep the refrigerant charge below the indicated
charge limits if possible. Above this limit; protect
the compressor against liquid flood-back with a
pump-down cycle or suction line accumulator.
• Never leave the filling cylinder connected to the cir-
cuit.
Compressor models
Refrigerant charge limit
MLZ015-019-021-026
3.6 kg / 8 lb
MLZ030-038-045-048
5.4 kg / 12 lb
MLZ058-066-076
7.2 kg / 16 lb
9 – Verification before commissioning
Use safety devices such as safety pressure
switch and mechanical relief valve in compliance
with both generally and locally applicable regula-
tions and safety standards. Ensure that they are
operational and properly set.
Check that the settings of high-pressure
switches don’t exceed the maximum service pres-
sure of any system component.
•
A low-pressure switch is recommended to
avoid low pressure operation.
Minimum setting for R22,
R452A and R513A
1.5 bar (absolute) / 22 psia
Minimum setting for R404A 1.8 bar (absolute) / 26 psia
Minimum setting for R407A 1.7 bar (absolute) / 25 psia
Minimum setting for R407F 1.9 bar (absolute) / 28 psia
Minimum setting for R134a,
R448A and R449A
1.45 bar (absolute) / 21 psia
• Verify that all electrical connections are properly
fastened and in compliance with local regula-
tions.
• When a crankcase heater is required, it must be
energized at least 8 hours before initial start-up
and start-up after prolonged shutdown.
• Please respect a 90 Nm ± 20 Nm for tightening
torque of all rotolock nut.
10 – Start-up
• Never start the compressor when no refrigerant is
charged.
• Do not provide any power to the compresor
unless suction and discharge service valves are
open, if installed.
• Energize the compressor. It must start promptly.
If the compressor does not start, check wiring
conformity and voltage on terminals.
• Eventual reverse rotation can be detected by fol-
lowing phenomena; the excessive noise, no pres-
sure differential between suction and discharge,
and line warming rather than immediate cooling.
A service technician should be present at initial
start-up to verify that supply power is properly
phased and that the compressor is rotating in
the correct direction. MLZ Scroll compressors are
designed to operate for a maximum of 150 hours
in reverse, but as a reverse rotation situation can
go unnoticed for longer periods, phase monitors
are recommended. For compressors MLZ048 and
larger, phase monitors are required for all applica-
tions. Danfoss recommends phase protection for
residential compressors.
• If the internal overload protector trips out, it must
cool down to 60°C / 140°F to reset. Depending on
ambient temperature, this may take up to several
hours.
11 – Check with running compressor
Check current draw and voltage. Measurement
of amps and volts during running conditions must
be taken at other points in the power supply, not in
the compressor electrical box.
• Check suction superheat to reduce risk of slug-
ging.
• Observe the oil level in the sight glass (if pro-
vided) for about 60 minutes to ensure proper oil
return to the compressor.
• Respect the operating limits.
• Check all tubes for abnormal vibration. Move-
ments in excess of 1.5 mm / 0.06 in require cor-
rective measures such as tube brackets.
•
When needed, additional refrigerant in liquid
phase may be added in the low-pressure side as far
as possible from the compressor. The compressor
must be operating during this process.
• Do not overcharge the system.
• Never release refrigerant to atmosphere.
• Before leaving the installation site, carry out a
general installation inspection regarding clean-
liness, noise and leak detection.
• Record type and amount of refrigerant charge
as well as operating conditions as a reference
for future inspections.
12 – Maintenance
Internal pressure and surface temperature are
dangerous and may cause permanent injury. Main-
tenance operators and installers require appropri-
ate skills and tools. Tubing temperature may exceed
100°C / 212°F and can cause severe burns.
Ensure that periodic service inspections to
ensure system reliability and as required by local
regulations are performed.
To prevent system related compressor problems, fol-
lowing periodic maintenance is recommended:
• Verify that safety devices are operational and
properly set.
• Ensure that the system is leak tight.
• Check the compressor current draw.
• Confirm that the system is operating in a way
consistent with previous maintenance records
and ambient conditions.
• Check that all electrical connections are still ad-
equately fastened.
• Keep the compressor clean and verify the ab-
sence of rust and oxidation on the compressor
shell, tubes and electrical connections.
• Acid / moisture content in system and oil should
be checked regularly.
13 - Warranty
Always transmit the model number and serial
number with any claim filed regarding this prod-
uct.
The product warranty may be void in following
cases:
• Absence of nameplate.
• External modifications; in particular, drilling,
welding, broken feet and shock marks.
• Compressor opened or returned unsealed.
• Rust, water or leak detection dye inside the compres-
sor.
• Use of a refrigerant or lubricant not approved by
Danfoss.
•
Any deviation from recommended instructions
pertaining to installation, application or mainte-
nance.
• Use in mobile applications.
• Use in explosive atmospheric environment.
• No model number or serial number transmitted
with the warranty claim.
14 – Disposal
Danfoss recommends that compressors
and compressor oil should be recycled by
a suitable company at its site.
