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:
Tire Sizes, AWD Vehicles
Note the following regarding AWD vehicles:
Only tires having the same size and are manufactured by the
same manufacturer and have the same profile may be used on the
front and rear.
Different rolling circumfe ...
Cleaning wheels
First read and observe the introductory information
and safety warningsCleaning steel wheels
An industrial cleaner is needed to remove accumulated brake dust. Steel wheels
should therefore be cleaned regularly with a separate sponge.
Any damage to the paint on steel wheels should be touched u ...
Seat belt routing
Fig. 52 Correct seat belt routing and
head restraint adjustment
Fig. 53 Correct seat belt routing during
pregnancy
First read and observe the introductory information
and safety warnings
Seat belts only provide an optimum level of protection during an accident when
they are routed corre ...
© 2016-2024 Copyright www.vwpolo.net
Compressor Types, Checking Pressures
Checking with Expansion Valve and Receiver/Dryer, with Internally Regulated
A/C Compressor