Volkswagen Polo Service & Repair Manual: Checking with Restrictor and Reservoir, 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. |
| – |
Pay attention to the A/C service station pressure gauge. |
Note
| Switching pressures for refrigerant circuit switches are
vehicle-specific.
|
| Connection with valve for low-pressure switch or at
evaporator is only to be used for vehicles with no service
connection on low-pressure side and inaccessible connection at
compressor or accumulator (measurement accuracy). Only applies
to certain vehicles. |
| 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 (measured at service connection) in bar (psi) |
| B - |
Low pressure (measured at connection with valve at
compressor or accumulator) in bar (psi). |
| C - |
Permissible tolerance range |
| D - |
Low pressure (measured at connection with valve for
low-pressure switch or at service connection) in bar (psi) |
| E - |
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
refrigerant circuit |
| – |
Check for leaks and correct. |
| – |
Charge the refrigerant circuit. |
|
| Low pressure in line with value in graph |
| Required cooling output is not attained |
|
|
|
| Low pressure too low (see graph) |
| Required cooling output is not attained |
|
|
|
Note
| If no malfunction is found with this complaint, 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 only increases slightly above pressure with
engine stopped
|
| Low pressure drops only slightly |
| Required cooling output is not attained |
|
A/C compressor faulty. |
| – |
Flush (clean) refrigerant circuit. Refer to
→ Chapter „Refrigerant Circuit, Flushing (Cleaning) with
Refrigerant R134a“. |
| – |
Replace A/C compressor. |
|
|
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. |
| – |
In the event of an obstruction, 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“. |
|
| High and low pressure normal at first After some time, |
| high pressure increases above specification |
| Low pressure quickly drops to value in graph or below, |
| Required cooling output is no longer attained. |
|
Moisture in refrigerant
circuit |
| – |
Flush refrigerant circuit with compressed air and nitrogen. |
| – |
Replace receiver/dryer. |
| – |
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. |
|
| Low pressure too low (see graph) |
| The required cooling performance is obtained |
|
A/C compressor faulty. |
| – |
Flush (clean) refrigerant circuit. Refer to
→ Chapter „Refrigerant Circuit, Flushing (Cleaning) with
Refrigerant R134a“. |
| – |
Replace A/C compressor. |
|
Note
| For the malfunction “high pressure normal, low pressure too low”,
note the following: |
| This fault may cause the evaporator to ice up or the A/C Refrigerant
Low Pressure Switch -F73- to shut off the compressor although the amount
of refrigerant in the circuit is OK. |
|
Possible deviation from specification |
Possible cause of fault |
Corrective
action |
| High pressure normal or too high |
| Low pressure too high (see graph) |
| A/C compressor noise (particularly after switch-on) |
| Required cooling output is not attained |
|
Too much refrigerant in the
circuit. |
| – |
Extract refrigerant from the refrigerant circuit |
| If quantity of refrigerant extracted roughly corresponds to
specified capacity: |
| – |
Replace the A/C compressor. |
| If quantity of refrigerant extracted is substantially
greater than specified capacity: |
| – |
Charge the refrigerant circuit. |
|
|
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. |
Note
Check cooling performance. The A/C system is functioning
correctly when the air flowing from the instrument panel vents
has a temperature of ...
Note
Connecting service station. Refer to
→ Chapter „Connecting Service Station“.
Observe test requirements ...
Other materials:
Side view
Fig. 1 Overview of the right side of
the vehicle Positions ③, ④, ⑤ and ⑤ are also at the same position on the left
side of the vehicle.
Key for :
Tank flap
Roof aerial
Attachment points for the mounts and
roof carrier
Door release lever
Exterior mirrors
Jacking p ...
Folding the seat cushion and backrests on the rear bench seat forwards and backwards
Fig. 82 Rear bench seat: folding the rear
seat cushion forwards
Fig. 83 Rear bench seat: release button
①, red marking ② or release button ③
First read and observe the introductory information
and safety warnings
The rear seat cushions and backrests can be folded forward to extend t ...
Pressure Gauge, Tests and Measurements
Indicators on pressure gauge
1 -
Temperature scale for refrigerant R134a CF3–CH2F or
CH2F–CF3.
2 -
Pressure scale
The pressure gauge may have one or more temperature s ...
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Compressor Types, Checking Pressures
Checking with Expansion Valve and Receiver/Dryer, with Internally Regulated
A/C Compressor