does your ac work? if so how well?

 

Yes, it still works. Still gets pretty cold. I forgot to mention that when the noise happens the engine hesitates slightly.

 

does it do it when idling? first thing i would do is look under the hood when then engine is running. if the compressor turning on and off is making the sound thats a start.

 

If the noise is coming from the vents, your expansion valve is going bad.

 

my car does this. its because i tightened the belt to much. Basically when the clutch in the A/C compressor engages the shock through the overtightened belt makes a squeek and puts killer stress on the engine.

 

it doesn't really put any more stress on the engine, just on the belt.

but yeah, check belt tension and make sure the bearings in the pulley are good.

 

its your turbo, dont mind it.

 

not turbo, bov

but seriously did you check this out?

 

My car has no turbo.

 

My car does this too. Pretty sure it's normal

 

when I turn the air on it sometimes does it, it sounds like a gentle whoosh coming from passenger side floor vents. I don't mind it mainly because I rarely have air on. I prefer windows down.

 

It's just the A/C compressor cycling on and off. Your compressor does this to keep the system from freezing up. When the compressor cycles on, the clutch engages and puts an extra strain on the engine. That strain will make the RPM's drop a little and you will feel that "hesitation". Then the ECM realizes the compressor is on and adjusts the idle. The "woosh" sound is just the refrigerant circulating through the lines along with the compressor kicking on. You may also hear a 'click'. It's all normal with an A/C system. When the compressor cycles off, you may hear another 'click' and the compressor clutch is disengaged. Your engine will run like the A/C isn't on.

 

Sorry to revive a dead thread but did you figure out what the problem was? I recently had my belts replaced and ever since when I turn on the AC I also get a "PSSSH" sound then it repeats every 20-30 seconds with slight engine hesitation. No, its not the compressor turning on I know the difference. I've had this car for 4 years and its never made that noise till now. Any thoughts OP?

 

That sound you hear is freon evaporating inside the evaporator, and is actually pretty common.

When you turn your AC on, the pump moves hopefully gas freon from the evaporator return line, into the condenser. Freon turns from a gas into a liquid, and moves along to the evaporator. In there, it turns from a liquid to a gas, and in doing so, cools the evaporator. It can cool the evaporator down to really cold temps, well below freezing point of water. If it does, water WILL condense and freeze on the surface of the evaporator core. Which is why there's a temperature sensor on the core, so when the temp goes under 32*F, it shuts off the compressor.

Once it's warmer, it kicks the compressor back on. Thus, you hear the evaporator core every now and then as it freezes/thaws, and you feel the power reduce slightly.

If you want a trick system, you'll have to look at another manufacturer. I think Ford uses variable displacement pumps. Way more efficient than the rotary pumps in Subies.

 

Ive had this car since late 07 and its never done this before. I find it hard to believe its just going to start out of the blue with no apparent cause. The only thing that has been done recently was the belts being replaced. It has to be related to that somehow.

 

Well... There are a few possibilities...

One is that it made it before and you didn't notice it.

 

Hi,

First let me just say sorry if it sounds like Im being a sarcastic jerk. I re read some of my earlier post and thought they could be taken the wrong way. Its hard to grasp someones tone online . Anyways I am for sure I never heard it. Just like the OP its as loud as a BOV at times so its really hard to miss.

This maybe totally unrelated but I also swear that my gas mileage has gone down since the noise started too. One would think it would be related to the AC being used but since this noise started, I have been driving with the windows down ( in 99+ heat no less ) . Couls an issue with the belts also cause the gas problem too?

 

It's possible that you have water in your freon, and this water is causing restrictions in your AC system, which is causing this noise. If this is the case, then you should have the system serviced, but you may need a new receiver dryer, which if memory serves, is built into the condenser core. IE, it's a bit expensive to replace.

Receiver Dryer has a desiccant in it that absorbs water; If it becomes saturated, it stops absorbing all of the water in the system, and should be replaced. Sometimes you can put a vacuum on the system for a good chunk of time and get the water out, but there really is no way of drying out the desiccant.