so when im driving and i rev past 4k something starts hissing in my car and then the a/c doesnt blow cold for a few seconds until the hissing goes away. what do you think it is?

 

Can you pinpoint the source of the hissing noise?

 

not at the moment i live in a gated appartment complex. its weird i know its on the driver side. and only happens when i rev past 4k then my ac stops blowing cold air. but once i let it rev down to around 3k and under it stops

 

Is the noise coming from the engine bay or the cabin?

Have you checked for a loose A/C belt or a seized idler pulley?

 

well i havnt actually checked it out yet. im pretty sure you can hear it from the outside but when im driving it sounds like its coming either from the air vent. on the driver side or underneath where the fuse box is. ill try to pin point it better tomorrow.

 

and how do i check for a seized idler pully. i dont really know what it looks like.

 

The idler pulley is marked in red. Loosen the center nut and then the adjusting bolt and test whether it spins freely.

 

ok i will test this out tomorrow. anything else you recommend?

 

so i was looking at it today. i rev the car up to about 3.5k 4k with the a.c on and the clutch on the compressor disengages. slowly letting the rpms down the clutch starts spinning again and this is what is causing the hissing noise. once it grabs it stops hissing. could this be a sign of a bad or going bad ac compressor?

 

Is the A/C belt loose or tight?

 

i wouldnt say it is loose. i can move it very little but it doesnt feel to tight to where it could break.

 

Sounds like a compressor problem, possibly a bad bearing or clutch.

 

any info on how to fix it? is it normal for the a/c to turn off when rev over 4k? once i go under 4k it turns right back on.

 

The problem may be a bad compressor clutch or clutch coil, which you may be able to test and replace without removing the compressor from the car.

 

The A/C clutch is designed to disengage the compressor at WOT or under excessive engine load.

 

What do you think about the hissing noise coming from the compressor apparently when the clutch disengages?

 

not when it disengages. when it tries to engage again. here is exactly how it goes. idle i turn a/c on its fine blows cold. i drive or sitting at idle i rev to around 3.5k-4k the clutch disengages i let off the gas and it tries to engage again. when it trys to start engaging it makes a loud hissing noise i can hear. i watched the compressor. once it engages again the hissing stops and the cold air comes back. but once it starts hissing its just blowing air from outside i guess. no cold. is it normal to disengage around 3.5k-4k? how could i test it o what ever you recommend me doing?

 

Not sure, but I think possibly the clutch gap may be a bit too wide or the clutch or clutch coil is faulty.

 

it just started doing it in the last 3days maybe. i got on the highway when it was raining and i kept hearing it but i just thought it was me driving through water. i was driving pretty fast on my way back home over 100mph.it was dry by then and i started hearing it again. now when im just driving around town i hear it all the time.