boiling noise from a/c evaporator

[EstoMax]

Hey Guys,

My 99 Impreza wagon is making a boiling noise seemingly from the evaporator for several minutes when i turn the car off after driving with the air conditioning on. I tried googling this but didn't come up with any general results so I was gonna throw it out there to see if anyone knows what could be going bad in the a/c system? If i shut off the car after driving without a/c the noise is not there, so definitely not coolant in the heater core

cheers
Marko

[Ashers]

If it is a hissing noise, or hissing and "bubbling", it is completely normal. The refrigerant has to equalize between the "Low" and "High" sides of the system. This will typically make hissing sounds. During operation you can see 30 PSI Low and 280 PSI high. Without the system running it typically sits around 80 PSI on both. My dad's old Caravan, my Civic, and my house A/C do it as well. Don't hear though on our German cars as they have more sound deadening.

[ACURA44]

it is normal for cars to make a noise after the a/c was in use. i find that cars with an orfice tube a/c system make more noise than cars with a TXV ststem. it could also be low or out of refrigerant, how is it working?

[EstoMax]

it still blows cold, maybe not AS cold as it used to... but i don't remember it ever doing it before that's why it intrigued me.

but if other peoples' cars do it then its ok. How would I tell if its low on refrigerant? (yeah yeah im too lazy to google)

thanks!

[ACURA44]

evacuate and recharge would be the only way to tell 100%. you can also do a preformance test and hook up some a/c gauges and make sure the pressures are doing what they should be. that would also be a way of finding out if there are any issues with the metering portion of the system (orifice tube or txv)