Automotive Air Conditioning Information Forum

I vacuumed the system for 2 hours, then charged from a half full tank. Takes 26 oz but could only get 16 oz in and air is nice and cold. Low side around 35 or 40, high maybe 220 if I recall and it's 85-90 degrees out. Tank scale started going down and high side was at 300 when the high speed fans kicked in and dropped it to about 250. Shut the valve off when the scale showed 13 oz which is half of what it should be. Air still seems cold. Any idea what is happening? Has 135K miles.

What did you do to the system that prompted you to evacuate and recharge?

For best results, on here, post hi, lo, ambient, vent temps at about 1500-1800 RPM, full load, meaning doors open, not recirculate. And are any/all fans engaged. Then we have something to sink our teeth into

which is it, 13 or 16

It took 16 oz and wouldn't take any more, and the compressor was engaged. I waited a few more minutes and the tank scale dropped to 13 oz. at which point I stopped. Air was cold then, but when I went for a drive, the air is blowing warmer than before I started. I'll get the gauges back on and see what they are now.

OK.
And what work was done to the system.....?

I don't know. Just got the truck.

A few questions:
How do you know that it takes 26 ounces? Under-hood decal?
What engine does it have?
Does it have front and rear A/C or front A/C only?
Are you sure that the low-side port adapter is fully depressing the Schrader valve by turning the thumb-wheel fully clockwise?
Are you charging it with the engine running at about 1,800 RPM?
Are you sure that the R-134a cylinder isn't actually empty?

How do you know that it takes 26 ounces? Under-hood decal? Yes decal
What engine does it have? 3.7L
Does it have front and rear A/C or front A/C only? Front only
Are you sure that the low-side port adapter is fully depressing the Schrader valve by turning the thumb-wheel fully clockwise? Yes
Are you charging it with the engine running at about 1,800 RPM? It was at idle. When it wouldn't take more I reved it a few times but didn't seem to help. Can try again with a pedal depressor for a longer time and see what it does.
Are you sure that the R-134a cylinder isn't actually empty? Yes it's 20 pounds

Okay, great.

Definitely raise the engine RPM to about 1,800, which should reduce the low-side pressure and help draw-in the rest of the refrigerant.

Added 10 more ounces to the 13 oz added before but compressor is cycling. 95 degrees now and high side going up to 430 psi at which point compressor disengages until it drops to about 300 psi. Low side seems excessive at 60 70 psi. Seems like low airflow through the condenser but the fans kick on high speed. Maybe the outside of the condenser blocked with dirt?

Is this a US vehicle?