Air in hydraulic system. Drain hydraulic system and fill with approved brake fluid. Replace defective hoses. Pump pedal then release and look for a return of fluid out of compensating port in master cylinder reservoir. Bleed hydraulic system.
Car pulls to one side.
Incorrect or loose pads. Grease or brake fluid on pads. Loose caliper or caliper mounting bracket. Caliper piston sticking. Replace with correct pads and plates in axle sets.