Anemic blower

I bought a 93 chevy 3/4 ton work tuck 8 years ago. From the beginning it has had anemic heater/ac blower performance from every outlet. I tried replacing the blower and it had no effect. Also my AC works quite poorly in that the compressor kicks off every 4 seconds. This results in me having to replace the electric switch every 6 months. I think these two things might be related.

Could the problem be caused by a blockage in the intake to the blower? If so, how do I correct that?

any thoughts?

This sounds like a major voltage drop.

Just for yucks and giggles, remove both side mount battery cables from the battery. On the red positive terminal, peel back that red rubber cover. If you find corrosion under this cover, replace the positive battery cable assembly.