2000 Chevy Blazer Automatic car seats

Do you mean the motor starts on it's own and moves the seat OR does the seat just slide without any control.

If it's the first one you have a problem with either the seat switches or the wiring itself.

If it's the second one either the transfer cables are failing or the motor drive gears are stripped. Easiest solution to both would likely be a replacement seat drive system. Used ones are not hard to find.

A couple more questions. One you say "automatic seats" do you mean standard power seats OR ones that are programmable for each person/ Also does it have power seats on driver and passenger seats or just the drivers seat? Does the seat move while your on it or does it move regardless if your on it or not?

The switch assembly is replaceable as a separate part. Basically the one in there has a retainer behind it. You remove the retainer and the switch pulls out from the side of the seat. Then you release the wire connector and remove it. Then reverse that to install the replacement. As for the switch price you would be better off to call a couple salvage yards about one. They seldom fail, but it does happen.