VW Tiguan Manuals

Volkswagen Tiguan Service and Repair Manual: Refrigerant Circuit Pressures (with A/C Service Station), Checking

Volkswagen Tiguan Service and Repair Manual / Refrigerant R134a Servicing / Pressures, Checking / Refrigerant Circuit Pressures (with A/C Service Station), Checking

Test Requirements

Note

  • Check cooling performance. The A/C system is functioning correctly when the air flowing from the instrument panel vents has a temperature of 70C or lower.
  • Setting on Climatronic "LO".
  • Setting on A/C system "AC" on; "max"; "cold".
  • Connections with valve and service connections for measuring and checking.
  • Radiator and condenser are clean (clean if necessary).

 

  • Thermal insulation at expansion valve OK and properly installe
  • Ribbed belt is OK and properly tensioned. Ribbed belt for A/C compressor and generator are OK and correctly tensioned.
  • All air ducts, covers and seals OK and properly installed.
  • Fault finding on the electrical equipment and vacuum system found no malfunction.
  • The A/C system OBD cannot find malfunctions with the Vehicle Diagnostic Tester in "Guided Fault Finding". The measured value block does not show any shut-off condition from the A/C compressor (only on vehicles with "A/C system" OBD).
  • Air flow through dust and pollen filter not obstructed by dirt.
  • The heater and A/C unit does not draw in any secondary air at the highest fresh air blower speed. Evaporator and heater not drawing in secondary air at maximum fresh-air blower speed.
  • The air flaps in the heater and A/C unit reach their end position.
  • Fresh-air intake ducts beneath hood and in passenger compartment as well as corresponding water drain valves OK, see vehicle specific Repair Manual.
  • The engine is warm.
  • Vehicle is not exposed to direct sunlight.
  • Ambient temperature greater than 15 ºC (60 ºF).
  • All instrument panel vents are open.
  • With engine running and maximum cooling output set on air conditioning system.

Maximum cooling output, setting

Setting on Front A/C Display Control Head -E87-.

  • Preselect "Auto" mode (A/C compressor on).
  • Set the temperature preset "LO" for the driver and front passenger sides.

Setting on heater controls:

  • A/C button and Rec- or recirculated air button pressed.
  • Temperature dial in the "Cold" position.
  • Fresh-air blower dial in "4" position.

 

  • The Coolant Fan -V7- runs (the fans run) (at least in level 1).*

Note

For some versions, the fan is switched on only once the pressure in refrigerant circuit has exceeded a specified value.

  • The Fresh Air Blower -V2- runs at maximum speed.
  • Recirculated/fresh-air door set to "air recirculation mode" (within 1 min. after starting vehicle, air-flow door is closed and recirculated air door opened).*
  • Is the coolant shut-off valve closed?*
  • Are the valves on the pump valve unit closed and the coolant circulation pump is not pumping? *

Pressures, Checking

Note

  • Check cooling performance. The A/C system is functioning correctly when the air flowing from the instrument panel vents has a temperature of 70C or lower.
  • Setting on Climatronic "LO".
  • Setting on A/C system "AC" on; "max"; "cold".
  • Connections with valve and service connections for measuring and checking.

 

  • Turn off the ignition.
  • Connecting service station.
  • Take pressure gauge readings (two possible results).
Ambient Temperature in ºC (ºF) Pressure in Refrigerant Circuit in bar (psi) Positive Pressure
15 (59) 3.9 (56.57)
20 (68) 4.7 (68.17)
25 (77) 5.6 (81.22)
30 (86) 6.7 (97.18)
35 (95) 7.8 (113.13)
40 (104) 9.1 (131.98)
45 (113) 10.5 (152.28)

Note

  • Temperature of refrigerant circuit components should be equal to ambient temperature.
  • Pressure will deviate from values in table if individual components of refrigerant circuit are warmer or colder.
  • At absolute pressure, 0 bar/psi corresponds to absolute vacuum. Normal ambient pressure (positive pressure) corresponds to 1 bar (14.5 psi) absolute pressure. 0 bar/psi pressure corresponds to an absolute pressure of 1 bar (14.5 psi) on most pressure gauges (indicated by 1 bar (14.5 psi) below 0).
  • On vehicles with High Pressure Sensor -G65- with which the measured pressure is displayed in the measured value block, the measured pressure should correspond to the values in the table.

The refrigerant circuit pressure is lower than indicated in table

Not enough refrigerant in refrigerant circuit

  • Determine refrigerant circuit leaks.
  • Check the pressure relief valve.

If pressure relief valve has responded:

  • Check the coolant fan activation.
  • Check refrigerant lines and hoses for cross-section constrictions caused by inadequate bending radii.
  • Check refrigerant pipes and hoses for external damage.
  • If no malfunction is found, flush refrigerant circuit with compressed air and nitrogen.

The refrigerant circuit pressure is in line with table or is higher

  • Start the engine.
  • For vehicles with an electrically-driven A/C compressor, switch on the ignition.

WARNING

Hybrid vehicles have a high voltage system. Danger of electrical shock! Inspect the high voltage components visually before beginning. Follow the General Warnings.

  • Set the A/C system to maximum cooling output.

Note

If the low pressure switch was removed to connect the service station, bridge the electrical connections in the corresponding connector for the pressure measurement.

  • A/C compressor is driven by the engine via A/C Clutch -N25-.
  • The A/C Compressor Regulator Valve -N280- is activated by the Climatronic Control Module -J255-.

If A/C compressor is not driven with the engine running or regulating valve is not actuated:

  • Determine and eliminate cause e.g. by checking air conditioner DTC memory.
  • Observe test conditions.
  • Check the A/C Clutch -N25- voltage supply. If it is OK, repair the A/C clutch.
  • Check activation of A/C Compressor Regulator Valve -N280-.

Compressor Types, Checking Pressures

Note

  • Check cooling performance. The A/C system is functioning correctly when the air flowing from the instrument panel vents has a temperature of 70C or lower.
  • Setting on Climatronic "LO".
  • Setting on A/C system "AC" on; "max"; "cold".
  • Connections with valve and service connections for measuring and checking.
  • Check on vehicles with restrictor and reservoir (with internally regulated A/C compressor).
  • Check on vehicles with expansion valve and receiver/dryer (with internally regulated A/C compressor).
  • On vehicles with expansion valve and receiver/dryer (without regulated A/C compressor).
  • Checking pressures for vehicles with restrictor, reservoir and A/C Compressor Regulator Valve -N280- (externally regulated A/C compressor).
    Pressures, Checking
    ...

    Checking with Restrictor and Reservoir, with Internally Regulated A/C Compressor
    Note Connecting service station Observe test requirements   Bring engine speed up to 2000 RPM. Pay attention to the A/C service station pressure gauge. Note Switching pressures for refr ...

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