hey anyone--I have a 1996 XJ with the 4.0 engine--after turning on the AC I am getting a incredible howl coming from the expansion valve--the thing vibrates and howls until the compressor cylcles off and then restarts when the compessor cycles on again--over and over//anyone have any experience with this--maybe I just need a new expansion valve//just recently I had the AC serviced and I needed about a pound of coolant which was put in--since then the howling began--thanks--Portuitalia

 

I don't know if I am having quite the same sound, but when I put my a/c on I get this whooshing, not quite the sound of a turbo but that similar to a much larger truck. It almost doubles the noise coming from the front end of the car, but its not engine noise. My guess would be one of the fans. A/c runs properly but I have no idea....

can post youtube video if necessary

any ideas?

 

turn off the engine and try turn the none electric fan. if its hard and resistant with a cold engine. then the vicose is bad. replace it will make the cure

 

I vacuumed my AC last year and juiced it up. It did good for a couple of days and then started doing the same thing yours is doing. It doesn't do it all the time it seems to take spells. I think the expansion valve is sticking. I know that's where the sound is coming from. I probably need to put a new one on if it gets any worse.
Good Luck!