Why does my blazer die when i turn on the a.c.?

Try doing the following.

Engine stalling issue at low speeds

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve. Buy a can of throttle valve cleaner from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control

IAC idler air control valve bumps up the RPM and doesnot let the engine to die, how ever if its not the IAC then Ide be looking at the TEMP sensor which migh have a fair line crack or may be the MAF mass air flow sensor might be bad, seems like the engine is not geting air, check the air filter first.

replace the electric part of the ignition down on the steering colum ....u will have to drop the steering colum down but not totaly remove...fixed 2 s-10 trucks same year that way

u need to check your idle stabilizer unit.

only half way there if you have a tbi check the crank sensor/ cam sensor that is the first line of business on that truck if the crankshaft sensor fails the truck stops dead when you wait a few minutes the sensor re energizes and the truck will work again for a bit antiknock can cause similer problems but not while the truck is running

sounds real easy either a bad idle air control solenoid or more likley a blown throttle body gasket. to test fro a blown gasket, with engine running and cool spray carb cleaner or brake cleaner around base of tb were it bolts to intake. when it hits the bad area, should idle down and be normal for a second or 2. iac is possible,try this first since its so common and let me know

check all your vacumm hoses, I think you may have a hole in the air intake hose to the engine, sometimes the hole is underneath the hose so feel around...goodluck!

do not think vacuum hose is teh issue. When ws last time you replaced fuel and air filter? Couls also be failing fuel pump, so need to check output pressure. If check engine light comes on may be in air polution control system. Need to pull code and see what circuit is causing the fault code. Sometimes an auto zone will read code for free.

Just having fuel is not enough on this engine, here are the spec's. Even 1 psi out of spec can cause a no start.

Fuel Pressure
Pressure 1 (PSI) Pressure 2 (PSI) Pressure 3 (PSI) Range Note Range Note Range Note 60.0 - 66.0 Y131 50.0 - 63.0 Y132 66.0 Y133 Y131: System pressure with ignition on (PSI).
Y132: System pressure while idling (PSI).
Y133: Fuel pump pressure (PSI) with return line briefly restricted.

there is a hose that goes from the intake manifold to the back of the fuel injection it is cracked or dry rotten.