All retrofit procedures must follow SAE guidelines.
My recommendations are in line with the aftermarket recommendations.
Aftermarket recommendations are those of companies such as Everco,
Four Seasons and Murray.
Volvo's Recommendations:
Volvo is a leader in the change over to ozone friendly R-134a.
They use R-134a in all vehicles 1993 and up.
They have retrofit kits avaliable for their cars and are the only
manufacturer to my knowledge to use ester oil in their retrofit procedures.
Their kit includes: a drier, ester oil, o-rings, special R-134a service ports,
R-12 block off cap, and a R-134a refrigerant label.
The cost of a kit to change over a Volvo 740 (part number 945660-8) is only $57.00 Volvo Retrofit Information
David retrofitted his Volvo and is putting information on the internet
to help others.
Recommendations From A/C Shops:
One of the major problems with Volvo R12 systems is not enough air
flow through the condenser.
At least make sure:
The condenser has clean fins and good air flow.
There are seals around the condenser to improve the air flow through it.
The fan clutch or the coolant fan motor is operating
properly.
That any air dams etc. are not missing.
MINERAL OIL REMOVAL
Remove and drain the compressor.
I recommend that you remove as much oil as possible!
FLUSHING THE SYSTEM
None Recommended
I recommend flushing of parts that are practicle, see general retrofit
procedures.
O-RINGS & GASKETS
All o-rings and gaskets replaced should be R134a compatible.
I recommend that you cover all o-rings and fittings w
HOSE REPLACEMENT
Replace hoses if they show signs of leaking.
COMPRESSOR
The compressor is not part of the normal retrofit.
When you do change a compressor make sure you know what type oil it
contains.
CONDENSER AND AIR FLOW (HEAT EXCHANGE)
Volvo does not make recommendations of condenser replacement.
We see potential problems and needs in this area, see general retrofit procedures.
When you do replace the condenser, try to use a improve multiflow model.
FILTER DRIER / ACCUMULATOR REPLACEMENT
Volvo recommends the replacement of the drier with one that contains XH-7
or XH-9 desiccant.
DT>EXPANSION VALVE
The expansion valve is not part of the normal retrofit.
EVAPORATOR
The evaporator is not part of the normal retrofit.
HIGH PRESSURE RELIEF VALVE (HPRV)
No recommendations.
HIGH PRESSURE CUTOUT (HPCO) SWITCH
No recommendations.
I think a high pressure cut out switch is a worth while safeguard.
On of the major problems I see with Volvo air conditioners is a bad fan clutch.
OTHER PARTS
No other recommendations.
OIL REPLACEMENT
Refill the system with a full charge of the proper Ester (retrofit) oil.
SERVICE PORT ADAPTERS
Special R134a only service ports that meet SAE requirements are required by
law.
REFRIGERANT REPLACEMENT FOR R12
Recharge the system with about 15% less R134a than the R12 specification.
LABELS
Special R134a service labels that meet SAE requirements are required by
law.