Several months ago, I purchased this used car with around 130,000 miles on it. It has had issues with the power steering, alarm, and air compressor. It's also making some whining noises. I had several repairs done already. The power steering pump was replaced twice. The differential was changed several times. Despite changing the alarm speaker twice already, it's now malfunctioning again. The air compressor is still making loud noise. The whining noise hasn't disappeared yet. In addition to that, I've been getting a significant drop in gas mileage, which is now 12 MPG on average What could be making this issues?
Hello. If the air compressor is faulty this will cause the engine to work harder and that may result in lower mpg. The whining noise could be caused by a bad serpentine belt, pulley, or a bad serpentine belt tensioner.
The alarm system problem sounds like it is a result of some electrical issues in that system that are causing the speaker to malfunction. The alarm system will need to be inspected and diagnosed by someone who specializes in this. If you need further help, have a certified technician, like one from YourMechanic, come and inspect the noises and other symptoms that are occurring in order to have these problems properly addressed.