Audi Q7 2007 Repair Manual page 225

head (on "Comfort" version) or switch off operating mode
"Econ" (on "Basic" version).
– Set temperature preselect "Lo" for driver's and front passeng‐
er's side or set temperature rotary switch of the Climatronic
Control Module - J255- front A/C control head to "cold" stop
(depending on A/C system version).
– Set direction of air flow to "instrument panel vents" on the Cli‐
matronic Control Module - J255- front A/C control head.
– Select "read measured values block". Use the Vehicle Diag‐
nostic Tester via the "Guided Fault Finding" function.
– Check the indicators in the various display fields on the tester
display:
♦ A duty cycle greater than 30% is shown in the display field for
the A/C Compressor Regulator Valve - N280- activation (the
valve -N280- is activated, the compressor is switched on).
♦ A current greater than 0.3 A is shown in the display field for
the current to the A/C Compressor Regulator Valve - N280-
(the current flows via the valve -N280- , the compressor is
switched on).
♦ The pressured measured by the High Pressure Sensor - G65-
and display increases over the value with the compressor
switched off.
Note
The A/C Compressor Regulator Valve - N280- is activated by
♦
the Climatronic Control Module - J255- front A/C control head
so that temperature of air downstream of evaporator in front
A/C unit reaches the specified value (approximately 2 to 5° C):
After vehicle start, depending on temperature, engine speed
♦
and vehicle voltage in the measured value block, a value
greater than 75 % (0.55A) is displayed for activation of the A/
C Compressor Regulator Valve - N280- .
As soon as the temperature measured by the Evaporator Vent
♦
Temperature Sensor - G263- approximates the specified val‐
ue, activation of the A/C Compressor Regulator Valve - N280-
is reduced and thus the compressor output is reduced.
If the pressure measured and displayed in the High Pressure
♦
Sensor - G65- does not change and compressor activation is
OK, check whether the compressor is actually being driven (an
overload protection is installed between the compressor and
the belt pulley/drive unit. The compressor will not be driven if
it has been triggered). If no malfunction is found, there is a
malfunction in the refrigerant circuit. Bring the vehicle to a
workshop that has the necessary tools and in which the work
can be performed accordingly by qualified personnel. Refer to
⇒ Refrigerant R134a Servicing; Rep. Gr. 87 ; A/C System
General Information (Refrigerant R134a, Servicing; A/C Sys‐
tem, General Information). If the compressor control is not OK,
then inform the workshop of the problem at hand.
The connector to the A/C Compressor Regulator Valve -
♦
N280- and the connector to the electric engine mounts are
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not identical in construction. If these connectors are interchanged,
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
no entry appears in DTC memory, however since the com‐
with respect to the correctness of information in this document. Copyright by AUDI AG.
pressor is continuously actuated (by the engine control mod‐
ule), the evaporator may ice-up.
– Press button for recirculating air mode on the Climatronic Con‐
trol Module - J255- front A/C control head (symbol for "recir‐
culating air mode" lights up in button).
Heating, Ventilation and Air Conditioning - Edition 04.2013
Audi Q7 2007 ➤
13. A/C Unit, Checking Cooling Output
219