no such thing
AC relay is inside fuse-box on driver-side inner fender. Relay diagram is inside cover.
R134a
R134a
R134a
R134a
it's in the high pressure side of the ac line
Aprox 12 qts, it varies if you have ac or not.
R-134
How to remove and install the serpentine belt on 1991 Chevy Blazer with AC?
it is located in the bottom line under the accumulator
You don't have one; crack a line to drain it.
A 1987 Chevy Blazer uses R12 refrigerant as shipped from the factory. Most have been converted to the more environmentally friendly R134a.