Whistling or hissing type noise in AC vent when compressor clutch activates

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Novice7
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Joined: Thu Oct 01, 2020 5:18 pm

Whistling or hissing type noise in AC vent when compressor clutch activates

Postby Novice7 » Thu Oct 01, 2020 5:56 pm

Hi,

I obviously created an account to seek any helpful feedback on my attempt to DIY on my Honda fit 2008 4-door sport AC system.
I have a little bit of experience with DIY with my cars.

I have replaced my condenser, vacuum pumped the AC system high and low side, and recharge successfully and other maintenance and replacement work, nothing advance like the engine block or ecu/mcu etc.

I wanted my ac to be colder, and I know I did not do a solid job as professionals would have. So, in my mind, I thought I could get the AC colder by adding more refrigerant. I was wrong, and didn't research that this does not do that at all, until after the fact...

What I have done to the car so far:

I attempted to recharge the system. But the gauge shows 0 PSI when the car is turned on, with the AC on full blast. When the car ignition is off, the pressure gauge shows at about 40 PSI, in the green.

I decided to make a dumb move, to want to fill to 50 PSI to the max where it shows in the green.

Now, my ac is blowing warm air.
Radiator fan kicks on automatically when I turn on the AC, the AC compressor clutch does not right away, only after about 5-10 minutes, it kicks on.

When that does happen, I notice a whistling noise coming from the AC vents in the car, which did not occur prior to the cold start with the AC compressor clutch not being activated.

I heard a pop sound when attempting to recharge, then the pressure gauge goes all the way down to 0 psi, with the ac and car ignition on. However, when the car is on the on ignition without the car being fired up, it shows the PSi is in the green around 45-50 psi right before the red. The AC fan still kicks on once the AC is turned on, the AC compressor clutch activates constantly still after 5-10 minutes being on.

I would take it to a AC shop, but at this moment, I can't afford to spend that type of money. So I am attempting to do it myself or at least research and diagnose the problem before attempting to fix it...

Base on my research, signs are pointing to the compressor? But I wouldn't know. Leaks? I have search top and bottom and have not seen any signs leaks so far.

Please, any feedback of what might be the issue is greatly appreciated.
Thank you.
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Cusser
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Re: Whistling or hissing type noise in AC vent when compressor clutch activates

Postby Cusser » Thu Oct 01, 2020 6:10 pm

Novice7 wrote:I attempted to recharge the system. But the gauge shows 0 PSI when the car is turned on, with the AC on full blast. When the car ignition is off, the pressure gauge shows at about 40 PSI, in the green.

I decided to make a dumb move, to want to fill to 50 PSI to the max where it shows in the green.


Apparently you do not have a real gauge set, to read both low pressure side and high pressure side at 1800 rpm or so. I sure hope you didn't use one of those miracle in a can things, and added refrigerant containing sealant !!! That's a no-no, and can cause serious damage.
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Tim
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Re: Whistling or hissing type noise in AC vent when compressor clutch activates

Postby Tim » Thu Oct 01, 2020 6:12 pm

Even a DIY needs a correct set of gauges for a/c.

https://www.ackits.com/mt1416-santech-r ... oses-24615
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Al9
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Location: Southern Europe

Re: Whistling or hissing type noise in AC vent when compressor clutch activates

Postby Al9 » Thu Oct 01, 2020 11:37 pm

The hissing from the vents is the expansion device trying to expand something that is already expanded (vapour, instead of liquid refrigerant). Just so you know, lubricant can't make it back to the compressor in this state of things.

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