okay so I have a 1999 honda civic ex(d16y8) if I turn the heater/ac on it will start to rev continuously, and makes a deep whistling sound(kind of sounds like blowing in a bottle) coming from the right side of the bay near the a/c pump, but the strange thing is if I turn the rear defrost on the noise goes away🤷‍♂️ and if I turn the climate control off my idle smooths out quite a bit. the car is throwing a p0505 for a IAC valve even after I swapped it out for a new one.

 

What is the idle speed with the A/C off and is the idle perfectly smooth or is there still some hunting?

Does P0505 return after you reset the ECU?

 

'new to you' or 'new out the box from the store bought and I don't care if its not oem'?

 

brand new outf of the box from autozone

 

with A/C off it idles smooth around 700-800. yes p0505 does return, sometimes it takes a couple good drives, but it never fails to reappear.

 

Do these tests: