Volkswagen Touran Service Manual: Checking with Expansion Valve and Receiver/Dryer, with Internally Regulated
A/C Compressor
 Note
| Connecting service station. Refer to
→ Chapter "Connecting Service Station". |
| Observe test requirements. Refer to
→ Chapter "Pressures, Checking". |
| |
Bring engine speed up to 2000 RPM. |
| |
Observe manometer battery. |
Note
| Switching pressures and design of refrigerant circuit
switches are vehicle-specific. |
| The pressures should be measured at the service connections.
The location of these connections is vehicle-specific. |
| Increasing from initial pressure (when connecting the
pressure gauges) to a maximum of 20 bar (290 psi). |
|
|
|
| Decreasing from initial pressure (when connecting pressure
gauges) to the value in the graph. |
| A - |
High pressure in bar (psi) |
| B - |
Low pressure in bar (psi) |
| C - |
Permissible tolerance range |
|
|
|
|
Possible deviation from specification |
Possible cause of fault |
Corrective
action |
| High pressure remains constant or increases only slightly
(above pressure with engine stopped), |
| Low pressure quickly drops to value in graph or below |
| Required cooling output is not attained |
|
Not enough refrigerant in
circuit or expansion valve malfunctioning. |
| |
Extract refrigerant from the refrigerant circuit |
| If quantity of refrigerant extracted roughly corresponds to
specified capacity: |
| |
Charge the refrigerant circuit. |
|
| Low pressure in line with value in graph |
| Required cooling output is not attained |
|
|
| If quantity of refrigerant extracted is substantially less
than specified capacity: |
| |
Localize the leak with leak detector and eliminate |
| |
Charge the refrigerant circuit. |
|
Note
| If no malfunction can be found and the function of the A/C
system is not correct after repeating the test, flush (clean)
refrigerant circuit with refrigerant R134a. Refer to
→ Chapter "Refrigerant Circuit, Flushing (Cleaning) with
Refrigerant R134a". If that is not possible in this
workshop, flush the refrigerant circuit with compressed air and
remove moisture with nitrogen. Refer to
→ Chapter "Refrigerant Circuit, Flushing with Compressed Air and
Nitrogen". |
|
|
|
|
Possible deviation from specification |
Possible cause of fault |
Corrective
action |
| High pressure increases above specification |
| Low pressure quickly drops to value in graph or below |
| Required cooling output is not attained |
|
| Constriction or obstruction in refrigerant circuit |
|
| |
Run hand over refrigerant circuit to check for differences
in temperature |
| If difference in temperature is found at one component: |
| |
Replace the hose or pipe if kinked or constricted. |
| |
If there is an obstruction, flush refrigerant circuit with
compressed air and nitrogen and replace expansion valve. |
| If no malfunction can be found. |
| |
Flush (clean) refrigerant circuit. Refer to
→ Chapter "Refrigerant Circuit, Flushing (Cleaning) with
Refrigerant R134a". |
|
Note
| If the function is not correct after flushing the
refrigerant circuit, the expansion valve must be replaced. |
|
|
|
|
Possible deviation from specification |
Possible cause of fault |
Corrective
action |
| High and low pressure normal at first |
| After some time, high pressure increases above specification
and low pressure drops to value in graph or below |
| Required cooling output is no longer attained. |
|
| Moisture in refrigerant circuit |
|
| |
Examine expansion valve for dirt or corrosion; replace if
necessary. |
| |
Flush refrigerant circuit with compressed air and nitrogen. |
| |
Repeat test if function is not OK. |
| |
Flush (clean) refrigerant circuit. Refer to
→ Chapter "Refrigerant Circuit, Flushing (Cleaning) with
Refrigerant R134a". |
| |
Charge the refrigerant circuit. |
|
Note
| Always replace receiver/dryer in case of this malfunction. |
|
Possible deviation from specification |
Possible cause of fault |
Corrective
action |
| High pressure normal or too high (see diagram), |
| Required cooling output is not attained |
| A/C compressor noise (particularly after switch-on) |
|
| Too much refrigerant in the circuit. |
| Expansion valve or A/C compressor faulty. |
|
| |
Extract refrigerant from the refrigerant circuit |
| If quantity of refrigerant extracted roughly corresponds to
specified capacity: |
| |
Charge the refrigerant circuit. |
| If quantity of refrigerant extracted is substantially
greater than specified capacity: |
| |
Charge the refrigerant circuit. |
|
Note
| If the function of the A/C system is not correct when the test is
repeated, re-install old expansion valve and flush refrigerant circuit
with compressed air and nitrogen. Then replace A/C compressor and
receiver/dryer. |
|
Possible deviation from specification |
Possible cause of fault |
Corrective
action |
| High pressure only increases slightly above pressure with
engine stopped |
| Low pressure drops only slightly |
| Required cooling output is not attained |
|
|
| |
Flush (clean) refrigerant circuit. Refer to
→ Chapter "Refrigerant Circuit, Flushing (Cleaning) with
Refrigerant R134a". |
| |
Replace A/C compressor and receiver/dryer. |
|
|
Possible deviation from specification |
Possible cause of fault |
Corrective
action |
| Low pressure too low (see graph) |
| The required cooling performance is obtained |
|
| Expansion valve or A/C compressor faulty |
|
| |
Charge the refrigerant circuit. |
|
Note
| If A/C system function is not OK when the test is repeated,
flush (clean) refrigerant circuit. Refer to
→ Chapter "Refrigerant Circuit, Flushing (Cleaning) with
Refrigerant R134a". Then replace A/C compressor and
receiver/dryer. |
| With this malfunction, evaporator may ice up although
quantity of refrigerant in circuit is OK. |
|
|
|
|
Possible deviation from specification |
Possible cause of fault |
Corrective
action |
| High and low pressure normal |
| Required cooling output is not attained |
|
To much refrigerant oil in the
circuit. |
| |
Discharge the refrigerant circuit. |
| |
Flush (clean) refrigerant circuit. Refer to
→ Chapter "Refrigerant Circuit, Flushing (Cleaning) with
Refrigerant R134a". |
|
| High and low pressure normal |
| A/C compressor noise (particularly after switch-on) |
| The required cooling performance is obtained |
|
|
|
Note
| Overfilling with refrigerant oil can occur in the event, for
example, the compressor has been replaced without adjusting the quantity
of refrigerant oil. |
| If the A/C compressor is not replaced, the refrigerant oil should be
drained from the A/C compressor via the oil drain plug. Out of the
entire quantity of refrigerant oil, 50 grams should be put in the A/C
compressor and the rest in the refrigerant circuit. Refer to
vehicle-specific repair manual. |
Note
Connecting service station. Refer to
→ Chapter "Connecting Service Station".
Observe test requirements. Re ...
Test Requirements
Radiator and condenser are clean (clean if necessary).
The ribbed belt for the A/C compressor and alternator
tensioned corre ...
Other materials:
Volkswagen Touran Owners Manual. Indicator lamp in the vehicle key
Fig. 19 Indicator lamp in
the vehicle key
First read and observe the introductory information
and safety warnings If a button in the vehicle key is
pressed briefly, the indicator lamp (arrow) flashes once. The lamp will flash
several times if the button is pressed and held, e ...
Volkswagen Touran Owners Manual. Stowage areas in the rear floor area
Fig. 117 Stowage areas in
the floor area of the second row of seats
First read and observe the introductory information
and safety warnings Place the floor mat (if fitted) to
one side.
To open, pull the lid up from the centre (arrow)
at the rear.
To close, press the lid do ...
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Checking with Restrictor and Reservoir, with Internally Regulated A/C
Compressor
Checking with Expansion Valve and Receiver/Dryer, without Regulated A/C
Compressor