Heating and Air Conditioning: Service and Repair
1 - Low-pressure pressure gauge
2 - High-pressure pressure gauge
3 - Torr meter
4 - Low-pressure shut-off valve (blue)
5 - High-pressure shut-off valve (red)
6 - Torr meter shut-off valve (black)
7 - Vacuum pump shut-off valve (yellow)
8 - Low-pressure flange
9 - High-pressure flange
10 - Refrigerant inlet shut-off valve
11 - Refrigerant outlet shut-off valve
12 - Refrigerant oil inlet shut-off valve
13 - Refrigerant oil vent valve
14 - Moisture indicator
15 - Oil tank vacuum flange
16 - Hourmeter
17 - Pilot light SUCTION END
18 - Pressure switch SUCTION/CLEANING
19 - Main switch ON/OFF
20 - Pressure switch HEATING
21 - Pilot light FAULT
22 - Pressure switch VACUUM PUMP
23 - Filling cylinder with weight scale
24 - Filling cylinder shutoff valve
25 - Filling cylinder high-pressure gauge
26 - Refrigerant oil suction nozzle
27 - Refrigerant oil reservoir inspection glass
NOTE: The manufacturer's operating and repair instructions must be observed when carrying out all work on the service unit.
Assembly work involving the refrigerant system
During all work on the air-conditioning system which necessitates opening the refrigerant system, the system contents must first be disposed of correctly. When doing so, follow the safety regulations.
Dirt and moisture must be kept out of the air-conditioning system's pipe system. Thorough cleanliness must therefore be ensured during all work. System components must never be cleaned on the inside with hot steam. Use only nitrogen for cleaning purposes.
When replacing a component, all openings must be closed off with suitable plugs.
General assembly sequence
1. Remove refrigerant by suction.
2. Remove faulty part.
3. Evacuate.
4. Check the system for leaks.
5. Rinse with refrigerant.
6. Empty the system by suction again.
7. Evacuate.
8. Fill.
NOTE: Pay attention to sealing rings when disconnecting or connecting the hose connections.
The charging valves are located in the area of the front right spring strut.
Removing Refrigerant By Suction And Cleaning:
NOTE: Close all valves before carrying out each work step.
A - close B - open
Suction removal, start End
1 - ON/OFF 3 - SUCTION/END
2 - SUCTION/CLEANING 4 - ON/OFF
* Pressure too high/filling cylinder full.
Drain off refrigerant from the filling cylinder into a refrigerant bottle (approx. 50 %).
Cleaning The Refrigerant:
A - close B - open
Cleaning, start End
1 - ON/OFF 3 - CLEANING/END
2 - SUCTION/CLEANING 4 - ON/OFF
* Pressure too high/filling cylinder full.
** One revolution OPEN. After approx. 15 minutes CLOSED.
A - close B - open
1 - ON/OFF
Instructions
* 1 open to * 2 OFF, then * 1 CLOSED and * 3 OPEN.
A - close B - open
1 ON/OFF
2 - VACUUM PUMP
Evacuation time at least 15 minutes.
Topping Up With New Refrigerant Oil:
A - close B - open
1 - ON/OFF
Filling Via The High-Pressure Side:
A - close B - open
1 - ON/OFF
2 - HEATING
* Pressure 8... 10 bar.
** If pressure is less than 8 bar.
After using the SECU, perform internal suction removal (see Removing Refrigerant By Suction And Cleaning, shown above); first close the hand valves on both suction lines.
Refilling the air-conditioning system
NOTE: In the event of Insufficient refrigeration performance, remove the refrigerant by suction, top up with the stipulated quantity and check the system for leaks.
1. Remove the refrigerant by suction using the service unit.
2. Determine the refrigerant oil quantity after the refrigerant has been removed by suction.
3. Fill up with new refrigerant oil.
4. Evacuate.
5. Fill with the stipulated amount of refrigerant.
6. Check the system for leaks.
Distribution of the oil quantity in the refrigerant circuit
Total oil quantity 195 ± 15 cu.cm
After suction removal from the system, the following quantities remain in the:
Condenser
2 x 20 cu.cm approx. 40 cu.cm
Evaporator approx. 30 cu.cm
Fluid tank with lines approx. 30 cu.cm
Compressor approx. 50 cu.cm
Circulating oil quantity in the refrigerant circuit approx. 60 cu.cm
NOTE: In new vehicles, the amount of oil removed by suction is approx. 15.... 40 cu.cm.
Oil removed by suction must be returned to the system.
Refrigerant oil removed from a previously run air-conditioning system may no longer be used (special-category waste).
After the refrigerant has been removed by suction and a component has been replaced, the oil quantity must be determined and topped up by the quantity remaining in the removed component.