Koko4

Okay, so I've got a strange and frustrating symptom .. and I don't really know where to start. It happens when the A/C button is on, and will immediately stop when I turn the A/C button off OR when I push in the clutch (to shift gears, or just in general).

It's this noise which sounds like it's a high-pitched radio-interference type noise. It almost sounds like the old school TV's that make that constant high-pitched noise as soon as you turn them on. If I don't do anything to stop it (ie: turning off the A/C button), it will come and go for about 5 seconds at a time. There's no real interval as to how often it happens..sometimes it will happen a few times within 5 minutes, other times it won't.

I turned the speakers all the way down to see if it was still happening, which it was. It seems to be coming more-so from the area behind the glovebox than anywhere else (or it seems this way while I'm driving). I'm guessing it's got something to do with the A/C button itself, not as much the A/C system. But why would it stop when the clutch is pushed in?! I am kind of stumped and didn't know if you guys would have any ideas of what this could be, or if anyone's encountered this weird problem before!

slowcivic2k

It sounds like you have refrigerant in the evaporator that is entering as a gas instead of a liquid, this can produce a very annoying squeal that can change as engine RPM changes.

Just to make sure we are chasing the right problem, can you hear it in the speakers or not? Electrical interference is totally different.

Koko4

I am very sure it's not electrical interference, which is what had me so baffled. Luckily it doesn't get any higher or lower pitched as the RPM's increase/decrease..it will just remain, or go away depending on if the A/C is on or if the clutch is pressed in.

So if this refrigerant which is supposed to be in a liquid state is entering the evaporator as a gas, what kind of problem would that usually be indicative of? I have been having problems with intermittent A/C, which started over the summer, but never accompanied by a noise. I didn't know how to start chasing these problems..sometimes it will blow cold as ice, and other times it will blow lukewarm (then start blowing cold again after about 10 minutes). I have visually checked the condenser fans and the A/C compressor clutch, which are operating as they should.

Would I possibly fix this by draining and recharging the refrigerant, or will this be a little more in-depth than that? Aside from checking the things I mentioned above, I wouldn't even know where to start..

slowcivic2k

Your low on refrigerant is the most likely cause, and there is a leak somewhere. On a few ocaisions the valve can get stuff caught in it which can make the noise more pronounced. Most of the time a recharge and test will fix that type of problem.

Koko4

Recharge the system and test for leaks with dye? Or other tests to check if the evaporator is working as it should? I have a feeling this will be a costly repair and I'd like to DIY it if I can. I also heard that around 80% of A/C leaking cases are just the valve stems up front, so it'd be a decent idea for me to change those.

confidence

slowcivic2k is most likely right. I've had the same issue several time.
In my case it was caused by a bad compressor once and a bad expansion valve the other time.
do as koko says and check for leaks.