Removing/installing and renewing air conditioner compressor regulating valve N280 — AUDI

Removing/installing and renewing
air conditioner compressor regulating valve
N280
Note
Certain
N280
malfunctions (e.g. valve sticking or open circuit in coil) can lead to problems with the air conditioner compressor (no air conditioner cooling action, icing-up of evaporator etc.). If
N280
is the cause (and not the actual air conditioner compressor), the air conditioner compressor can be repaired by renewing
N280
C, D
.
N280
C, D
is not available as replacement part for all air conditioner compressors. If
N280
cannot be obtained as a separate air conditioner compressor component, the entire air conditioner compressor must be replaced
Electronic parts catalogue
.
There are different versions of
N280
with different assignments
Electronic parts catalogue
. On the air conditioner compressor
A
(in this case a
“Denso”
air conditioner compressor without
air conditioning system magnetic clutch
N25
), the connector for connection to the vehicle wiring harness is attached to
N280
C
via a short wiring harness. On the air conditioner compressor
B
(in this case a
“Sanden”
air conditioner compressor), the connector for connection to the vehicle wiring harness is attached directly to
N280
C
. Removal and installation of
N280
C, D
for other air conditioner compressors (different type, different make) are essentially the same and usually only differ slightly from the procedure described below.
N280
is available in different versions and with different settings
Electronic parts catalogue
. On air conditioner compressors with
N25
(in this case a
“Denso”
air conditioner compressor), the connector for connection to the vehicle wiring harness is attached directly to
N280
A
. On the other air conditioner compressor, the connector for connection to the vehicle wiring harness is incorporated into a 3-pin connector
E
for
N25
and
N280
.
On version
B
of
N280
, the wiring may be connected directly to
N280
or there may be an additional connector at
N280
.
The procedure for removing and installing versions
A and B
of
N280
is essentially the same and usually only differs slightly from the procedure described below. On air conditioner compressors with a 3-pin connector
E
, disconnect the wires to
N280
from
N280
, unplug them from the connector
E
or sever them at a suitable location (and re-connect them using wiring connectors from
wiring harness repair set
VAS 1978 B
.
If, after removing
N280
, the cause of the problem at
N280
is found to be dirt, swarf or some other form of air conditioner compressor abrasion, clean the refrigerant circuit and replace the air conditioner compressor
Chapter
“
Renewing air conditioner compressor on account of leakage or internal damage
”
and
Chapter
“
Cleaning (flushing) refrigerant circuit with refrigerant R134a
”
Removing
Drain the refrigerant circuit
Chapter
“
Working with the air conditioner service station
”
.
Caution
Risk of air conditioner compressor damage if the refrigerant circuit is empty
Never start the engine when the refrigerant circuit is empty.
Depending on the version of the air conditioner service station, the pressure in the refrigerant circuit may be less than 1 bar absolute following drainage.
Depending on the version, the air conditioner compressor may be damaged by running it when the pressure in the refrigerant circuit is low.
Never start the engine if the pressure in the refrigerant circuit is below ambient pressure.
Depending on the vehicle and the installation location of the air conditioner compressor, remove the components impeding access to
N280
Heating, air conditioning
Rep. gr.
87
Refrigerant circuit; System overview - refrigerant circuit
(vehicle-specific Workshop Manual).
On vehicles on which it is not possible to detach or remove at least one of the two refrigerant lines and
N280
with the air conditioner compressor attached to the engine.
Removing the air conditioner compressor
Heating, air conditioning
Rep. gr.
87
Air conditioner compressor
(vehicle-specific Workshop Manual).
Note
With the air conditioner compressor in position, a refrigerant line has to be detached to ensure that the pressure in the air conditioner compressor is the same as the ambient pressure.
On vehicles on which it is possible to detach or remove at least one of the two refrigerant lines and
N280
with the air conditioner compressor attached to the engine (air conditioner compressor is not removed)
WARNING
Risk of injury (frostbite).
Before removing
N280
, connect the air conditioner service station and extract refrigerant. The refrigerant circuit must be empty; danger of injury.
Refrigerant and refrigerant oil will emerge if the refrigerant circuit has not been drained.
The refrigerant is to be extracted before removing
N280
. Renewed evaporation may create pressure in the refrigerant circuit if
N280
is not removed within 10 minutes following extraction. Extract refrigerant again.
Check the pressure in the refrigerant circuit again by way of the pressure gauge of the air conditioner service station.
If the pressure displayed is higher than the ambient pressure (greater than approx. 1 bar absolute), switch the air conditioner service station on again and extract the refrigerant causing the pressure build-up.
Detach one of the two refrigerant lines from the air conditioner compressor
Heating, air conditioning
Rep. gr.
87
Refrigerant circuit; System overview - refrigerant circuit
(vehicle-specific Workshop Manual).
Note
With the air conditioner compressor in position, a refrigerant line has to be detached to ensure that the pressure in the air conditioner compressor is the same as the ambient pressure.
All vehicles
Before removing
N280
, check again whether the air conditioner compressor is actually being driven by the pulley/drive unit. If the overload protection device of the pulley or drive unit has been tripped, the malfunction is usually not caused by the regulating valve, but by the air conditioner compressor (e.g. because it is stiff).
Note
This illustration shows
N280
B
for a
“Sanden”
air conditioner compressor of type
“PXE 14”
. With these air conditioner compressors, the connector for connection to the vehicle wiring harness is attached directly to
N280
B
. Removal and installation of
N280
B
for other air conditioner compressors (different type, different make e.g.
“Denso”
,
N280
with a short wiring harness to the connector for example) may differ. The basic procedure is however the same, as described below for the
“Sanden”
air conditioner compressor of type
“PXE 14”
.
This illustration shows an
N280
B
with an O-ring
E
(not fitted on all versions).
In the case of an
N280
B
with no O-ring
E
, dirt may ingress into the mounting for
N280
C
as far as the O-ring
F
.
If fitted, unfasten the wiring from
N280
B
to the vehicle wiring harness connector from the air conditioner compressor.
Note
On air conditioner compressors with
air conditioning system magnetic clutch
N25
on which
N25
is activated via the same connector as
N280
B
, eject the corresponding wires from the connector (e.g. with an ejector from the
wiring harness repair set
VAS 1978 B
)
Heating, air conditioning
Rep. gr.
87
Refrigerant circuit; System overview - refrigerant circuit
(vehicle-specific Workshop Manual).
If an air conditioner compressor with
air conditioning system magnetic clutch
N25
has a connector from which the electrical wires cannot be ejected, sever the wires to
N280
(or to
N25
) at a suitable location and re-connect using wiring connectors from the
wiring harness repair set
VAS 1978 B
(or renew the connector; refer to
Electronic parts catalogue
)
Electrical system
Rep. gr.
97
Connectors; Repairing electrical wiring harnesses and electrical connectors
.
Thoroughly clean the air conditioner compressor in the area of the circlip
A
and
N280
B
.
Caution
The pressure in the air conditioner compressor must be the same as the ambient pressure.
Refrigerant and refrigeration oil may emerge in the event of higher pressure in the air conditioner compressor.
Dirt may be drawn into the air conditioner compressor in the event of lower pressure in the air conditioner compressor.
Ensure pressure equalisation before removing
N280
B
.
Remove the circlip
A
.
Carefully remove
N280
B
from the mounting on the air conditioner compressor
C
using a suitable screwdriver
D
for example.
After removal, check
N280
B
and the mounting on the air conditioner compressor
C
for contamination.
Note
If the strainer
D
,
N280
B
as far as the O-ring
F
or the mounting on the air conditioner compressor
C
is severely contaminated in this area (e g. with swarf or dark, tacky abrasion), this is an indication of air conditioner compressor damage. In this case, clean the refrigerant circuit and replace the air conditioner compressor
Chapter
“
Renewing air conditioner compressor on account of leakage or internal damage
”
and
Chapter
“
Cleaning (flushing) refrigerant circuit with refrigerant R134a
”
If the strainer
D
at
N280
B
and the mounting on the air conditioner compressor
C
as far as the sealing surface of the O-ring
F
are only slightly contaminated (e g. with light grey deposits from normal air conditioner compressor operation), the cause of air conditioner compressor malfunctioning may be a problem with
N280
B
.
If
N280
B
does not have an O-ring
E
, dirt may have entered the mounting
C
as far as the O-ring
E
during operation. Carefully remove all dirt using a lint-free cloth or similar (do not use compressed air).
Installing
Check the mounting on the air conditioner compressor
C
and the groove for the circlip for contamination and clean carefully and thoroughly with a fresh lint-free cloth if necessary.
Caution
Dirt in the air conditioner compressor or damage to the sealing surfaces in the mounting could lead to renewed failure of
N280
B
or the air conditioner compressor
If necessary, carefully clean the mounting on the air conditioner compressor
C
with a fresh lint-free cloth (do not use compressed air).
When cleaning the mounting
C
, make sure no dirt ingresses into the area beneath the sealing surface for the O-ring
F
or into the ducts provided and that none of the sealing surfaces of the mounting are damaged.
Check mounting for air conditioner compressor
C
for damage (also check for small scratches on the surface; renew air conditioner compressor if damage is found).
Check the O-rings
F,G,H
and
E
(if fitted) of
N280
B
for damage.
Moisten the O-rings
F,G,H
and
E
(if fitted) of
N280
B
with a small quantity of refrigeration oil and check for proper attachment.
Insert
N280
B
as far as it will go in the mounting on the air conditioner compressor
C
.
Fit a new circlip
A
and check for correct positioning in the groove.
Re-install all parts removed in reverse order.
Evacuate and re-charge the refrigerant circuit
Chapter
“
Working with the air conditioner service station
”
.
Note
If refrigeration oil has emerged with
N280
B
removed, use the air conditioner service station to add this quantity of refrigeration oil when charging the refrigerant circuit
Chapter
“
Working with the air conditioner service station
”
.
Check operation of the air conditioner
Chapter
“
Checking pressures
”
and
Heating, air conditioning
Rep. gr.
87
Refrigerant circuit; System overview - refrigerant circuit
(vehicle-specific Workshop Manual).