Chevrolet 1998 Express Van Owner's Manual page 309

Air Conditioning Refrigerants
Not all air conditioning refrigerants are the same.
If the air conditioning system in your vehicle needs
refrigerant, be sure the proper refrigerant is used. If
you're not sure, ask your dealer.
TYPE
QTY Front Only
QTY Front
and Rear
Refrigerant 3.00 lbs. (1.36 kg)
4.5 lbs. (2.04 kg)
R- 134a
Air Conditioning Refrigerant Capacity
NOTICE:
R-134a refrigerant is not compatible with R-12
refrigerant in an air conditioning system. R-12 in
an R-134a system will cause compressor failure,
refrigerant oil sludge, or poor air conditioning
system performance.
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