Danfoss Maneurop LTZ-R404A, Instructions Manual

• In all cases, the application limits of the compressor
must be respected; moreover, high superheat
values lead to high discharge temperatures and
decrease compressor capacity. The maximum
discharge temperature is 130°C: operating at a
higher temperature may result in refrigerant
decomposition.

• Under steady-state operating conditions, check
refrigerant piping or capillary tubes for abnormal
vibrations (refrigeration line movement in excess
of 1.5 mm necessitates corrective actions, pipe
brackets, etc.).

• Monitor the oil sight glass (when mounted)
to ensure proper oil return to the compressor.
After 2 to 4 hours of operations under established
conditions, check the oil level and add oil if
necessary (refer to TI 2-025). If oil return continues
to perform poorly, further investigation of the
piping design is required.

• Ensure that refrigerant flow through the liquid
line sight glass (when mounted) is adequate
and that operating temperatures correspond with
system specifications.

• When needed, refrigerant may be added in the
liquid phase, carefully throttling the refrigerant
on the low-pressure side and as far as possible
from the compressor. The compressor must be
operating during this process.

Do not overcharge the system.

11 – Troubleshooting

• Compressor failure to start: verify that the
compressor is hooked up to the power supply;
check the power lead connections and all suitable
capacitors on single-phase models. If these
verifications reveal no abnormality, control the
motor windings with an ohmmeter.

Note: when the internal motor protector has
tripped out, it may take up to several hours toreset
and restart the compressor.

• Compressor failure to build up pressure: check
to make sure that all bypass valves in the system
have not been opened.
Also check that all solenoid valves are in their
proper position. If the internal pressure relief valve
is open, the compressor sump will be warm and the
compressor will trip out on the motor protector. If
this happens, it may take up to 2 or 3 hours to
reset and automatically restart thecompressor.

• Abnormal running noise: ensure the absence
of  any liquid flood-back to the compressor by
means of measuring the return gas superheat
and compressor sump temperature. The sump
should be at least 10K above the saturated suction
temperature under steady-state operating conditions.

• The high-pressure switch trips out: check
condenser operations (condenser cleanliness, fan
operations, water flow and water pressure valve,
water filter, etc.). If above check out OK, the problem
may be due to either refrigerant overcharging or the
presence of a non-condensable (e.g.air) in the circuit.

• The low-pressure switch trips out: check
evaporator operations (coil cleanliness, fan
operations, water flow, water filter, etc.), liquid
refrigerant flow and pressure drops (solenoid valve,
filter dryer, expansion valve, etc.), refrigerant charge.

• Low refrigerant charge: the correct refrigerant
charge is given by the liquid sight glass
indication, the condenser delta T in relation to the
refrigerant pressure tables (pressure-temperature),
the superheat and the sub-cooling, etc.(if additional
charge is deemed necessary, refer to the “Filling
the system” section).

• Compressor maximum short cycling: there must
be a minimum delay of five minutes between two
compressor starts. DCC recommends the com-
pressor should run at least two minutes after
each start, and between each stop and start must
be three minutes standstill. Only during pump
down cycle, the compressor may run much shorter
until the pumpdown pressure has been reached
or when safety devices will prohibit compressor
further operation.

12 - Maintenance

Maneurop

®

compressors do not necessitate any

special maintenance procedure. However, it
must be recalled that proper operations and
maintenance of the system serve to prevent
against system-related compressor problems.
The following preventive maintenance checks, to
be performed at regular intervals, are highly
recommended:

- Control operating conditions (evaporating

temperature, condensing temperature, com-
pressor discharge temperature, temperature
difference on heat exchangers, superheat,
sub-cooling). These conditions must always
remain within compressor operation limits.

- Verify that safety devices are operational and

properly set.

- Check the compressor oil level and quality; this

step may include an acid test, humidity check,
spectrometer analysis, etc. whenever the oil
becomes discolored.

- Ensure that the circuit is leak tight.
- Verify the proper operation of heat exchangers

and, if necessary, clean them.

- Check the current draw on the compressor

motor as well as proper voltage balance
between phases.

- Check that all electrical connections are still

adequately fastened.

- Make sure the compressor is clean and in

good working order; verify the absence of rust
on the compressor shell, piping and electrical
connections.

- Make sure the refrigerant charge is suitable for

both winter and summer operations. Insure
that periodic in-service inspections required by
local regulations are performed.

13 – Replacement

Precaution must be taken when disconnecting,

cutting or drilling holes in the tubing to ensure that
no refrigerant under pressure is present in the
system.

The refrigerant shall not be discharged

directly into the atmosphere; rather, it must be
removed using approved reclamation techniques
and equipment and then safely stored, in
accordance with applicable legislation.

The presence of refrigerant vapor can

displace air and lead to suffocation. Proper
ventilation is mandatory at all times when servicing
the equipment.

A refrigeration system component change

must be carried out in compliance with local
regulations.

• Make sure that the main power supply has been
switched off.

• Before replacement, it is necessary to determine
the cause of failure and implement remedial action.
If such analysis and repair are not performed,
repetitive failure may occur. Note that an oil acidity

test always proves helpful in diagnosis when
undertaking compressor replacement.

• Check that the new Maneurop

®

compressor and

the on-site compressor to be replaced display the
same electrical and refrigeration performance
characteristics.

• Use the rubber grommets and gaskets supplied
with the new compressor.

• Whenever piping needs to be modified, please
refer to the «

Safety measures prior to assembly

»

section.

• For further details on replacement steps, refer to
the previous sections of this manual.

Note:

In the event of motor failure, flush and clean

the entire circuit before replacing the compressor
in order to remove acids and contaminants.
Systematically install a new filter dryer on the liquid
line. Prior to this step (if necessary), run the system
for at least 2 hours with anti-acid cartridges (in such
instances, the installation of a suction filter might
also be required). After an operating period of
approximately 2 weeks, check the level of oil acidity.
If the oil acid test proves positive, drain and replace
the oil, replace the anti-acid liquid line filter dryer
cartridges and the suction filter previously installed.
Repeat oil and filter dryer replacements until the
system is clean and acid-free. When there is no
longer any sign of acidity, replace the anti-acid
cartridges by the standard model and remove the
suction strainer cartridge as required.

14 - User advisory 

Insist that all service operations only be performed
by qualified personnel.

The compressor and tubing surface tempe-

ratures may exceed 100°C (212°F) and cause
severe bodily burns. Special precaution must be
taken when working around the compressor and
refrigerant tubing. Moreover, a compressor
inoperation can generate very cold surface
temperatures (as low as -45°C / -49°F), thereby
exposing personnel to the risk of freezing burns.

Pressure inside the compressor can reach

dangerously high levels (e.g. abnormal operation,
fire,…) leading to personnel injury if suddenly
released; therefore, never drill, weld or cut the
compressor shell and adjacent tubing (release of
liquid refrigerant can cause flash freezing on
exposed skin).

Be aware that the product warranty may be
deemed null and void in the following cases :

• external modifications to the compressor
(absence of nameplate, drilling, welding, broken
feet, shock marks),

• compressor opened by the customer or returned
unsealed (i.e. open discharge or suction ports),

• presence of rust or water inside the compressor,

• addition of leak-detection fluid in the lubricant,

• use of a refrigerant or lubricant not approved by
Danfoss Commercial Compressors,

• any deviation from recommended instructions
pertaining to installation, application or maintenance,

• use in mobile applications (boats, trains, trucks,
etc.) or under explosive atmospheric conditions
(the compressor connecting box is not explosion-
proof).

The date of production of the compressor is indi-
cated on the nameplate. Ensure that the model
and serial number information is always trans-
mitted with any claim filed regarding this product.

Instructions

5

8510196 P02-A   © Danfoss Commercial Compressors 06/04