There are 3 bolts at the top by the grille. There is also a hose with a clip on the right hand side. Badabing badaboom.
You have a vacuum hose disconnected or broken. Check under the hood for a small vacuum hose out of place or broken.
my chevy blazer 1984 the air conditioner blows from down side only.
No.
IT starts @ the intake manifold & ends on the front axle.
Section 4-31 of Chilton Book #28160
The PCV vacuum supply hose is located under the intake manifold. It is not uncommon for this hose to tear and create a vacuum leak. Removal of the intake manifold is needed in order to get access to this hose as there is not enough room to get hands or tools into that small area.
It should set a code or two but, check the MAP sensor and the vacuum hose leading to it.
The best way to repair a vacuum hose on your Chevrolet is to replace the vacuum hose. The vacuum hose is held in place with a retaining clamp on each end of the hose.
Try looking in Mitchel's OnDemand5 program under Engine Performance/Vacuum diagrams for this vehicle, Hope this'll help.
A vacuum diagram for a 1995 Chevy S10 Blazer 4.3 will show the various vacuum hoses and components connected to the engine. It typically includes labels for each hose and component, indicating their functions and the connection points. The diagram is used for diagnosing and troubleshooting issues related to the vacuum system of the vehicle.
assuming your talking about the transmission modulator...visually inspect the transmission and look for a vacuum hose from the engine to the tranny...