My a/c wasn't putting out very good so I added a small can of freon. Worked great the day I did it. Next day, it was raining out so I hit the a/c. Thats when it sounded like something fell into the fan, loud line-hammering sound. The faster the motor ran, the louder it got. I freaked out, pulled over and popped the hood to see what was hitting the fan. Found nothing. Turn off the a/c, noise went away.

Went and purchased a can of a/c oil and tried to put it in. It wouldn't go in. But I did notice that the a/c lines were jumping around, hence "line-hammer". After I tried to put the oil in and noticed it wasn't going in, I took my pocket knife and tried pushing the valve core down to see if there was any pressure in it. When the system is pressurized, you should still be able to push the valve core down, right? ANYWAYS,,,HELP

Also makes that same noise, just quieter when I turned on the heat, but I'm thinking te a/c was still engaged when I freaked out and hit the heat. Noise and jmping lines up fron by the fill valve.

P.S. I did search the forum and couldn't find this symptom. Thanks for any input.

 

Need to put gauges on it, and see what your pressures are doing.

 

Yep!

Those stupid cans they sell in stores are made by mechanics so they get your big $$$ when your whole system takes a dump!

It needs a particular amount of freon and oil. No dumping just a can in here or there.

I've had warm AC and no AC. Each time was when the system was fine but it was off on lbs. just a fraction. Take it to a shop, and have it filled PROPERLY.

 

A/C can easily be over charged , you need to measure both the high and low sides , if either is off then you have problems. There are also different types of oil and precise amounts specific systems need.

At this point you may need to have it vac'ed down and recharged with the correct amounts of refrigerant and oil.