hello, i am working on a 99-04 car. it is making a rubbing noise on the left rear. i took the caliper off and drove the car without it and no noise. so i go to compress the caliper in to put it back on the car and it won't budge. i open the bleeder and try it and it won't even budge, no fluid is being shot out. so i open the master cylinder cap and it had some pressure behind it. the caliper compressed a little after that but it stopped. so i opened the back line at the proportioning valve and now the caliper would compress easily and fluid is squirting out. there is something wrong with that one brake because it makes a screaching noise when going slow, it is sticking. does this sound like a bad caliper. i don't think it is the proportioning valve because only one side of the back brakes is making a noise.