Brake question

Passenger wheel locks up. Calipers replaces twice, rotors once, brake line once. Still locks up. Mechanic has given up. Has less that 89K miles and don’t want to junk it.

Have you replaced the flexible rubber line leading to the caliper? Sometimes the material inside them deteriorates and flakes off. When that happens the floating pieces get lodged in the hose and either restrict pressure or restrict release of pressure.

You don’t say front or rear or how long after caliper replacement the problem returns. I suspect proper caliper sliding surfaces lubrication procedures are not being used,second suspicion is that park brake issues are not being correctly resolved.

The next thing would be the proportioning valve i suppose.

What year, model, ABS(yes or no) and front or back brake. Did mechanic check for an abs code?

94 olds 88. front passenger side. Problem re-occurred basically immediately after caliper/rotor replacement. I don’t think it has abs. I think he replaced or at least checked the rubber line to the caliper.
Would park brake affect only one wheel?
How big a job is proportioning valve?
Its an old car but in great condition other than this so we want to keep it running.