AC Blowing hot

PMMERRY

MEMBER
2007 NISSAN ALTIMA
2.5L
4 CYL
2WD
MANUAL
168,000 MILES

Good Afternoon I have a 6 speed MT.
I was getting mildly cool air out of my AC.
I checked the static pressure. It was 72psi(low) / 72psi (high).
AC Clutch engages. 33psi (low), 65psi (high).
https://photos.app.goo.gl/Bxes75hGgP4QhaYL7

Then I tried to charge it.
Got static pressure 60psi (low) / 60psi (high).
AC Clutch Engages, 33psi (low) / 35 psi (high)
https://photos.app.goo.gl/1NwCWxWquX3yUVhn8

I tried recharging it again, but got lower levels.
I got Static 45psi (low) / 45psi (high).
https://photos.app.goo.gl/hfHvHUefAWaWNPEG9

I had a problem with the Manifold gauges, and lost a lot of pressure, so I tried again when it was hotter (80degrees).
Static Pressure 45psi (low) / 45psi (high).
AC Clutch engages 35psi (low) /50psi (high).
Low pressure line is hot.
High pressure line is room-temperature-cold idling at 15,000 RPM.
Tried charging again with virtually no changes.
No changes in pressure at 30,000-40,000 RPM.
https://photos.app.goo.gl/4EGheHC3VQuuMo8FA

Also, at the end I did hear a little extra noise from when my compressor is engaged.
Not sure if this is the original problem, or if overcharging/undercharging would cause the compressor to sound like this.

I have very clean lines, no leaks, no oil-residue on the lines, the condenser, the txv valve, or any of the fittings at the receiver/drier, or hoses.

Any ideas.
It did blow mildly cold air, but obviously I messed it up by trying to charge it.

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

Hi PMMERRY,

Sounds very much like a compressor but based on what you said, it does sound like it is overcharged at this point but normally overcharge pressure shows the high side really high like almost 300 PSI.

I would start from the basics and perform an evac and recharge and see what pressures you have after you are sure you have the correct amount of freon in it. Also, this will ensure there is no moisture in the system. Moisture in the system just really hurts the efficiency.

Once this is complete if your high side pressure is still low like this then most likely the compressor is to blame. Especially when you pull it down into a vacuum and it holds. This confirms no leaks.

Then when you get the system charged again, a restriction in the system will show you really high, high side pressure and most likely the low side will be very slow to recover and may even pull into a vacuum when the compressor cycles.

If the high side should be just over two times the ambient temp. If it is low again, then most likely the compressor is not pressurizing.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system