I tried to refill freon by myself and I made mistake by going over the pressure limit.. I quickly lowered the pressure to the right limit but the damage has already been done.

AC still works and gives out cold air but when it's set at fan speed 2 or faster, it will try to start then shut off. After a few seconds, it'll try to turn on and die again. And rarely it'll turn on and run fine for a whilte but it'll start to make knocking sound and go off.

However, when it's set at fan speed 1, it still works pretty good.

I talked to mechanic, it might be the switch that might be wrong. I set up an appointment but just want to know what I should be expecting and how much I am looking at.

Thanks!

 

Two questions:

1) How many miles does your car have?

2) Why did you have to add R134 refrigerant. Was the car completely blowing hot air or was it still blowing some cold air but you felt it should be colder?