Testing heating capacity of air conditioner and checking functioning of pump/valve unit — AUDI

This test checks the functioning of the pump/valve unit (heat regulation valves -N175/-N176 and coolant circulation pump -V50).

If the temperatures obtained are lower than the specification (insufficient heating capacity):

Check functioning of heat regulation valves -N175/-N176 and coolant circulation pump -V50 => Electrical testing,Page
01-196
.

If no fault is found:

Check whether coolant hoses (from engine and from heat exchanger for heater to pump/valve unit) have been interchanged => Page
87-65
and

=> Appropriate Engine, Mechanics Workshop Manual; Repair Group 19
Appropriate Engine, Mechanics Workshop Manual

Check whether electrical contacts of pump -V50 have been interchanged (running direction).

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

Special tools, testers and other items required

Fault reader V.A.G 1551 (or vehicle system tester V.A.G 1552) with wire V.A.G 1551/3

Test requirements:

Coolant circuit bled properly:

=> Appropriate Engine, Mechanics Workshop Manual; Repair Group 19
Appropriate Engine, Mechanics Workshop Manual

All air ducts, covers and seals OK and properly fitted.
Air flow through dust and pollen filter not impaired by dirt.
Engine warm.
Code checked and, if necessary, corrected => Page
01-106
.
Vehicle not exposed to sunlight.
Basic setting performed => Page
01-101
.
Fault memory interrogated => Page
01-104
.

Testing

Close bonnet.
Switch on ignition.
Close doors, windows and sun roof.
Start engine and let it run for a few minutes with maximum cooling capacity (compressor ON, temperature preset to "LO" for left and right-hand side).
Switch off ignition.
Press "Rest" button on operating and display unit -E87 (-E87 is switched on, pump -V50 does not run, valves -N175 and -N176 are closed).

Note:

The operating time for the "Rest" function is limited to approx. 10 minutes by the operating and display unit -E87.

Read measured value block, display group 014, =>Page
01-158
.
Check display in display zone 3 and 4.

Specification:
Ambient temperature plus max. 15°C

Set temperature preselection for driver's side to "HI" at operating and display unit -E87.
Check display in display zone 3 (temperature increases).
Specification: approx. engine temperature
(pump -V50 running, valve -N175 open)

Check display in display zone 4 (temperature remains virtually constant).
Temperature increase less than 10 °C
(valve -N176 closed)

Set temperature preselection for front passenger's side to "HI" at operating and display unit -E87.
Check display in display zone 4 (temperature increases).

Specification: approx. engine temperature
(pump -V50 running, valve -N175 and -N176 open)

Set temperature preselection for driver's and front passenger's side to "LO" at operating and display unit -E87.
Check display in display zone 3 and 4.
Specification: Temperature drops to ambient temperature (plus max. 15 °C) within 5 minutes
(pump -V50 running, valves -N175 and -N176 closed)