t
| Before drilling out, some parts have to be removed from the expansion valve. |
t
| There are two types of expansion valve. For type -A-, parts -B-, -C- and -D- must be removed. Separate regulator -E- from component -D-. Then drill through expansion valve in area -F- using a suitable 6 mm dia drill. |
t
| On version -G-, parts -H-, -I- and -K- must be removed and then area -L- drilled out with a suitably sized drill bit (6 mm in diameter). |
t
| Clean away any swarf from the drilled out expansion valve. |
t
| Reinstall parts -B-, -C- and -D- on type -A- or part -H- on type -G-. |
Note On vehicles with two evaporators, the circuit to the second evaporator must be isolated from the circuit to the first evaporator and purged in a separate procedure → Heating, air conditioning and → Chapter. |
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| Check the refrigerant volume in the air conditioning bottle. There must be at least 7 kg of R134a refrigerant. |
Note Switch on the heater attached to the refrigerant bottle 30 minutes before the first purging process, if necessary. In this way, pressure in the refrigerant bottle is increased and charging of the purging circuit is accelerated. |
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| Drain the waste oil container of the air conditioner service station. |
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| Connect the supply hose (high-pressure side) of the air conditioner service station with an adapter → Chapter to the low-pressure line leading to the air conditioner compressor (line with larger diameter). |
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| Connect the return hose (low-pressure or suction side) of the air conditioner service station to the outlet of the purging device for refrigerant circuits. |
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| Connect the inlet of the purging device for refrigerant circuits with an adapter → Chapter to the high-pressure line leading to the air conditioner compressor (line with smaller diameter). |
Note t
| The components are always purged against the direction of refrigerant flow when the air conditioning system is in operation → Chapter. |
t
| When purging, contaminants from the refrigerant circuit enter the purging device for refrigerant circuits and the air conditioner service station and are retained in the filters and dryers installed within. Depending on the contaminants, these components must be changed at shorter intervals in accordance with the operating instructions for the air conditioner service station or purging device for refrigerant circuits. |
t
| The filter in the purging device for refrigerant circuits should be changed after about 2 purging cycles (purged vehicles), depending on the level of contamination from the purged refrigerant circuits. If a heavily contaminated refrigerant circuit is purged (the refrigerant oil from the refrigerant circuit is black and viscous or there are large amounts of shavings in the refrigerant circuit) renew filter after purging refrigerant circuit. After such heavy contamination of the refrigerant circuit, we suggest purging the system again after changing the filter. |
t
| Depending on the type of contamination, deposits (old refrigerant oil and abrasive wear particles from the air conditioner compressor) will gather in the sight glass(es) of the purging device for refrigerant circuits. Clean sight glass(es) after purging and purge refrigerant circuits again. |
t
| Fluid refrigerant cannot flow at the necessary speed through the expansion valve, the restrictor and the dryer cartridge of certain receivers. These components must therefore be removed and an adapter installed in their place → Heating, air conditioning. |
t
| Adapters to connect air conditioner service station and to bridge certain components of refrigerant circuit → Chapter. |
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| Switch on the air conditioner service station and purge the refrigerant circuit (duration approx. 1 to 1.5 hours for one purging cycle with three purgings using approx 4 Kg refrigerant R134a). |
Note t
| The purging process of the refrigerant circuit should be carried out in accordance with the operating instructions of the air conditioner service station |
t
| Depending on the type of air conditioner service station, the waste oil container has a capacity of only approx. 125 cm3. If a system with a greater amount of refrigerant oil has to be purged, it may be necessary to empty the waste oil container after the first purge of the purging cycle. |
t
| Watch the refrigerant that flows out of the refrigerant circuit. When the refrigerant flows through the sight glass of the purging device into the air conditioner service station clear and completely free of colour, the refrigerant circuit is cleaned. |
t
| When purging, the whole amount of refrigerant oil from the refrigerant circuit is cleaned (except for a small amount in the evaporator, though this is not important). |
t
| Where contamination is particularly high, it may be necessary to carry out the purging cycle twice (two purging cycles with three purges each). Purging device filter must be renewed before starting second purging cycle. |
Sequence of purging process (sequence is carried out automatically in accordance with the air conditioner service station programme) |
t
| After switching on, the purging cycle (refrigerant circuit with connection hoses and purging device for refrigerant circuits) is first evacuated and the refrigerant circuit thereby checked for leaks. Depending on the type of air conditioner service station, it may be necessary to continue the sequence manually. |
t
| In the evacuated rinsing circuit, a predetermined amount of refrigerant is filled (e.g. 4 kg) via the high-pressure side of the air conditioner service station (against the normal direction of flow for air conditioner operation and thereby on the low-pressure side of the vehicle refrigerant circuit). Depending on the type of air conditioner service station, refrigerant is filled until the purging circuit is completely filled with liquid refrigerant. This can be identified, for example, by the fact that after a certain period of time no more refrigerant flows through. |
t
| Once the predetermined amount of refrigerant has been filled in the system, the heater, for example, of the purging device for refrigerant circuits is switched on depending on the type of air conditioner service station and purging device for refrigerant circuits (only if the refrigerant is extracted in gaseous form out of the purging device for refrigerant circuits). |
t
| When the refrigerant has been extracted, the heater of the purging device (if fitted) for refrigerant circuits is switched off, the refrigerant circuit may have to be evacuated briefly again depending on the design, and following evacuation so that the air conditioner service station can separate out the refrigerant oil. |
t
| The sequence for filling with refrigerant, extracting (and evacuating) is carried out twice (that means a total of three times). |
t
| After extracting for the third time, the purging circuit is evacuated depending on the type of air conditioner service station. |
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| Once the purging cycle is complete, check the sight glass (or sight glasses) for refrigerant circuits. If this is dirty, clean it in accordance with the operating instructions of the purging device for refrigerant circuits or the air conditioner service station. Carry out a purging cycle once more as a precautionary measure. One purging cycle is sufficient (approx. 30 min.). |
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| Check the pressure in the refrigerant circuit. There must be no pressure in the refrigerant circuit (evacuate again briefly if necessary). |
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| Remove the connections to the air conditioning service station from the refrigerant circuit of the vehicle (there should be no pressure in the refrigerant circuit) |
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| Renew these components according to the type of vehicle. |
t
| Restrictor and reservoir |
t
| Expansion valve and receiver or dryer cartridge in receiver |
Note t
| There is a predetermined amount of refrigerant oil in the genuine air conditioner compressor. On vehicles with two evaporators, a certain amount of refrigerant oil may have to be added to the circuit as appropriate → vehicle-specific workshop manual. |
t
| If the air conditioner compressor does not have to be renewed, the volume of refrigerant oil in the air conditioner compressor must be replenished in accordance with the fill volume (pour out refrigerant oil and refill the prescribed amount in the air conditioner compressor or the refrigerant circuit) → Chapter (renewing components of refrigerant circuit) and → vehicle-specific workshop manual. |
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| Evacuate and fill the refrigerant circuit as per specifications → Chapter and → Chapter. |
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