Checking and adjusting CO2 level in auxiliary heater exhaust gas (heater type "S") — AUDI

Test requirements

Coolant temperature less than 30°C
Ambient temperature less than 20°C
Second battery -A1 OK and adequately charged
Sufficient fuel in tank (fuel gauge in dash panel insert not in red zone)

Checking:

Switch off ignition.
Switch on exhaust analyzer V.A.G 1788 and insert corresponding hose of exhaust probe into exhaust pipe -A- of auxiliary heater.
Switch on auxiliary heater.

As soon as operating and display unit for air conditioner/Climatronic -E87 is switched on (by auxiliary heater), it is to be set to maximum heat output (temperature preselection "Hi").
Allow auxiliary heater to run in full load mode for approx. 5 minutes and then read off CO2 (carbon dioxide) level on measuring instrument.

Specification:

9.5 to 12 % by vol. CO2

Notes:

Exhaust probe must not impede emergence of exhaust gas from exhaust pipe during test.
If measured value is outside permitted range:
Check combustion air blower intake area for dirt and clean if necessary.
Check fuel delivery => Page
82-76
.
Adjust CO2 level in exhaust gas.

If starting problems are encountered with auxiliary heater although fuel delivery is OK, adjust CO2 level towards upper specification limit.

Adjusting CO2 level in exhaust gas:

Switch off ignition.
Remove noise insulation.

=> General Body Repairs; Repair Group 50; Removing and installing noise insulation
General Body Repairs
Removing and installing noise insulation

Switch on exhaust analyzer V.A.G 1788 and insert corresponding hose of exhaust probe into exhaust pipe of auxiliary heater.

Switch on auxiliary heater.
Allow auxiliary heater to run in full load mode for approx. 5 minutes and then adjust CO2 (carbon dioxide) level by turning CO2 adjusting screw.

Setting:

10 to 11.5 % by vol. CO2

Following adjustment, secure CO2 adjusting screw with locking fluid.

Notes:

CO2level in exhaust gas can only be altered to a limited extent by turning CO2 adjusting screw (do not screw in screw as far as stop or screw it out such that it projects).
If CO2level in exhaust gas cannot be adjusted although fuel delivery is OK:
Check electrical components of auxiliary heater (combustion air blower) =>Page
82-206
.
Dismantle auxiliary heater and examine burner element as well as seals =>Page
82-142
.