1996-2006 Volkswagen LT Van Checkingpressuresonvehicles -> 10.2 Checking systems with a restrictor and collector... User Manual
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Checkingpressuresonvehicles -> 10.2 Checking systems with a restrictor and collector... for Your Volkswagen LT Van Second Generation (1996-2006)

Amarok 2011 ➤ , Beetle 2012 ➤ , Bora 1999 ➤ , CC 2010 ➤ , CC 2012 ➤ , ...  
Air conditioning system with refrigerant R134a - Edition 10.2014  
Note  
If the low-pressure switch had been removed in order to connect  
the air conditioner service station, bridge the electrical connec‐  
tions in the respective connector for pressure measurement.  
•
•
The air conditioner compressor is driven by the engine via the  
air conditioning system magnetic clutch - N25- .  
The air conditioner compressor regulating valve - N280- is ac‐  
tivated by the Climatronic control unit - J255- .  
⇒ Rep. gr. 87  
If the air conditioner compressor is not driven or the lrkegulating  
valve not activated when the engine is running:  
– Determine the cause, e.g. by reading the event memory for  
the air conditioning system, and rectify it.  
– Observe the test prerequisites.  
– Check power supply for air conditioning system magnetic  
clutch - N25- . If this is OK, repair magnetic clutch.  
– Check actuation of air conditioner compressor regulating valve  
- N280- .  
⇒ Rep. gr. 87 .  
10.1.3  
Continuation of checking pressures  
♦ Where vehicles have a restrictor and reservoir, check these  
(with internally regulated air conditioning system compressor)  
⇒ page 130 .  
♦ Where vehicles have an expansion valve and receiver, check  
these (with internally regulated air conditioner compressor)  
⇒ page 135 .  
♦ Where vehicles have an expansion valve and receiver, check  
these (without internally regulated air conditioner compressor)  
⇒ page 141 .  
♦ Where vehicles have a restrictor and reservoir and air condi‐  
tioning system compressor regulating valve - N280- (external‐  
ly regulated air conditioning system compressor)  
⇒ page 143 .  
10.2  
Checking systems with a restrictor and  
collector (with internally regulated air  
conditioner compressor)  
Note  
♦ Connecting air conditioner service station ⇒ page 126 .  
♦ Observe the test prerequisites ⇒ page 127 .  
– Raise engine speed to 2,000 rpm.  
– Observe air conditioner service station pressure gauge.  
130  
Rep. gr.00 - Technical data  
Amarok 2011 ➤ , Beetle 2012 ➤ , Bora 1999 ➤ , CC 2010 ➤ , CC 2012 ➤ , ...  
Air conditioning system with refrigerant R134a - Edition 10.2014  
Note  
♦ Switch pressures for switches in refrigerant circuit are vehicle-  
specific.  
♦ The connection with a valve for the low-pressure switch or on  
the evaporator should only be used where the vehicle does  
not have a service connection on the low-pressure side and  
access to the connection on the air conditioner compressor or  
reservoir is not possible (measurement accuracy). This only  
applies to certain vehicles.  
⇒ Rep. gr. 87  
10.2.1  
Specifications:  
High-pressure side:  
Rising from starting pressure (when pressure gauge is connec‐  
ted) to maximum 20 bar.  
lk  
Low-pressure side:  
Falling from starting pressure (when pressure gauge is connec‐  
ted) to diagram value.  
A - High pressure (measured at the service connection) in bar  
positive pressure.  
B - Low pressure (measured at the connection with the valve at  
the air conditioner compressor or at the reservoir) in bar positive  
pressure.  
C - Permitted tolerance range.  
D - Low pressure (measured at the connection with the valve for  
the low-pressure switch or at the service connection) in bar pos‐  
itive pressure.  
E - Permitted tolerance range.  
Possible deviation from specification  
Possible cause of fault  
Rectifying fault  
•
High pressure remains constant or in‐ Insufficient refrigerant in cir‐  
creases only slightly (above the pres‐ cuit.  
sure measured when the engine is  
– Look for leaks and rectify them.  
– Recharge refrigerant circuit.  
stopped),  
•
•
Low pressure falls quickly to the dia‐  
gram value or lower,  
The required cooling output is not de‐  
livered.  
•
•
High pressure is normal,  
Low pressure matches the diagram  
value,  
•
The required cooling output is not de‐  
livered.  
10. Checking pressures on vehicles  
131  
Amarok 2011 ➤ , Beetle 2012 ➤ , Bora 1999 ➤ , CC 2010 ➤ , CC 2012 ➤ , ...  
Air conditioning system with refrigerant R134a - Edition 10.2014  
lk  
Possible deviation from specification  
High pressure is normal,  
Possible cause of fault  
Rectifying fault  
•
•
Low pressure is too low (see dia‐  
gram),  
•
The required cooling output is not de‐  
livered.  
Note  
If no fault can be found for this complaint, purge (clean) refrigerant  
circuit with refrigerant R134a ⇒ page 67 . If this is not possible in  
your workshop, blow through refrigerant circuit with compressed  
air and dry with nitrogen ⇒ page 65 .  
Possible deviation from specification  
Possible cause of fault  
Rectifying fault  
•
High pressure increases only slightly The air conditioner compressor is de‐ – Purge (clean) refriger‐  
above the pressure measured when fective.  
the engine is stopped,  
ant circuit ⇒ page 67 .  
– Renew air conditioner  
compressor.  
•
•
Low pressure falls only slightly,  
The required cooling output is not  
delivered.  
Possible deviation from specification  
Possible cause of fault  
Rectifying fault  
•
•
•
High pressure rises above specifica‐ Restriction or obstruction in the refrigerant – Feel the refrigerant  
tion,  
circuit.  
circuit with the hand  
to sense the tem‐  
perature gradient.  
Low pressure falls quickly to the di‐  
agram value or lower,  
•
At one component a  
temperature gradi‐  
ent will be detected:  
The required cooling output is not  
delivered.  
– If a hose or pipe is  
kinked or crushed,  
renew it.  
– In case of an ob‐  
struction, blow  
through refrigerant  
circuit with com‐  
pressed air and ni‐  
trogen.  
– Repeat the check; if  
the system does not  
operate correctly  
– Purge (clean) refrig‐  
erant circuit  
⇒ page 67 .  
132  
Rep. gr.00 - Technical data  
Amarok 2011 ➤ , Beetle 2012 ➤ , Bora 1999 ➤ , CC 2010 ➤ , CC 2012 ➤ , ...  
Air conditioning system with refrigerant R134a - Edition 10.2014  
Possible deviation from specification  
Possible cause of fault  
Rectifying fault  
•
•
•
•
High pressure and low pressure are Moisture in the refrigerant circuit.  
normal at first, but after a time,  
– Blow through refrig‐  
erant circuit with  
compressed air and  
nitrogen.  
The high pressure increases beyond  
lk  
the specified value,  
– Renew receiver.  
The low pressure falls to the diagram  
value or lower,  
– Repeat the check; if  
the system does not  
operate correctly  
The cooling power called for is not  
delivered.  
– Purge (clean) refrig‐  
erant circuit  
⇒ page 67 .  
– Recharge refriger‐  
ant circuit.  
– Repeat check.  
•
•
High pressure is normal,  
The air conditioner compressor is defec‐ – Purge (clean) refrig‐  
tive.  
erant circuit  
⇒ page 67 .  
Low pressure is too low (see dia‐  
gram),  
– Renew air condi‐  
tioner compressor.  
•
The cooling power required is deliv‐  
ered.  
Note  
♦ If the fault is “high pressure normal, low pressure too low ”  
please note the following:  
♦ In this case, the evaporator may be iced up or the low-pressure  
switch for air conditioning system - F73- has switched off the  
air conditioning system compressor, although the correct  
quantity of refrigerant is present in the refrigerant circuit.  
10. Checking pressures on vehicles  
133  
Amarok 2011 ➤ , Beetle 2012 ➤ , Bora 1999 ➤ , CC 2010 ➤ , CC 2012 ➤ , ...  
Air conditioning system with refrigerant R134a - Edition 10.2014  
Possible deviation  
from specification  
Possible cause of fault  
Rectifying  
fault  
•
•
High pressure nor‐ Too much refrigerant in – Extract  
mal or too high,  
circuit.  
some re‐  
frigerant  
from the  
refriger‐  
ant cir‐  
cuit.  
Low pressure too  
high (see dia‐  
gram),  
•
The air conditioner  
compressor is  
noisy (especially  
immediately after  
being switched  
on),  
•
The  
quantity  
of refrig‐  
erant ex‐  
tracted is  
about  
•
The required cool‐  
ing output is not  
delivered.  
equal to  
the pre‐  
scribed  
charge  
quantity.  
– Renew  
the air  
condition‐  
er com‐  
pressor.  
•
The  
quantity  
of refrig‐  
erant ex‐  
tracted is  
signifi‐  
cantly  
lk  
greater  
than the  
prescri‐  
bed  
charge  
quantity.  
– Recharge  
refriger‐  
ant cir‐  
cuit.  
– Repeat  
check.  
Possible deviation from specification  
Possible cause of fault  
Rectifying fault  
•
High-pressure and low-pressure Too much refrigerant oil in circuit.  
– Drain refrigerant cir‐  
cuit.  
are normal,  
•
The required cooling output is not  
delivered.  
– Purge (clean) refrig‐  
erant circuit  
⇒ page 67 .  
•
•
High-pressure and low-pressure  
are normal,  
The air conditioner compressor is  
noisy (especially immediately af‐  
ter being switched on),  
•
The cooling power required is de‐  
livered.  
134  
Rep. gr.00 - Technical data  

Related Topics

Checkingpressuresonvehicles
10.1 Checking pressures in refrigerant circuit... 10.3 Checking systems with an expansion valve and reservoir... 10.4 Checking systems with expansion valve and reservoir... 10.5 Checking systems with a restrictor and reservoir... 10.6 Checking systems with an expansion valve, receiver... 10.7 With expansion valve, receiver and electrical compressor

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