99 two door Tahoe AC help
 

This is my sons Tahoe and the AC is about to get the better of both of us.
What’s been done so far-
New compressor
New hoses
New receiver/dryer
New condenser
New expansion valve (black)
Flushed out evaporator
Vacuumed the system down for two hours.
Compressor came with 3 ounces of oil added 4 ounces, two in compressor and two in recieiver dryer, gave the compressor a few spins by hand after putting on the hoses
Added two full 12 ounce cans and maybe half of another.
Low side pressure about 55-56
High side 230 ish
Vent temp around 68
Outside temperature at the time was around 90
Both heater hoses clamped shut with vice grips
It will get the receiver/dryer and the hose going back to the compressor sweaty and the evaporator is dripping a little.
AND it still doesn’t cool, any ideas?

Re: 99 two door Tahoe AC help
 

Temp control panel is operating correctly? Make sure the temp control knob wasn't cracked, just spinning on the shaft? Have you tested your pressure control switches? Pressures look good, Is your compressor cycling normal? I'm not an expert in AC just a few things I had to trouble shoot recently.
Jeff

Re: 99 two door Tahoe AC help
 

Compressor comes on and stays on. The control panel appears to be ok, everything lights up, vent positions and defrost work correctly and blows hot air or cool when the temperature control is turned.

Need a little more information
 

Even though your pressures look ok, when you vacuumed it down, did you leave it sit with the vac pump off for a good while to be sure it held vacuum? Sorry we don't know these things if it isn't written. One would expect if it was leaking, the numbers would be off.

I stopped relying on the rudimentary gauge on the vacuum pumps years ago and only vacuum with a "micron" gauge. https://www.trutechtools.com/MicronGauges
Several times I have gotten to the end of the vacuum pump gauge only to discover later there was still a leak. If you can achieve 500 microns of vacuum (using the micron gauge obviously) or lower, you instantly know there is no leak. But that's beside the point of your problem.

OK you mentioned outside is 90 and vent temp is 68. Do we assume the air temp going into the AC is 90? If that's the case, you have a delta of 22°.

Over 20 is acceptable. Much more than that is hard to achieve. Now if you tell us the doors were closed and it was in recirculate and the air going in the intake was 80, you would have a problem.

From the photo it appears you have 64°. There are 5 divisions in a 20° span on the gauge therefore each division is 4°. Also, those gauges are notoriously wrong by varying amounts. It's always a good idea before using it, to put in a glass of ice water to be sure of 32°F/0°C.

Did you close the windows and put it on recirculate and see what the temp was after about 20 minutes? You have to remember we don't know how you tried it, how long you tried it and what was the temp inside the vehicle (even though the outside was 90°).

I was not aware of an expansion valve in these vehicles. Only an orifice tube. Is that what you meant by "black"?

Re: 99 two door Tahoe AC help
 

Orifice tube, the different colors (white or black) are to determine use with or without rear AC. The black is supposedly are for units without rear AC.
Temperatures is with doors shut and recirculate on.
Used regular AC gauges for vacuum because that’s what I’ve got. Pulled a vacuum until the needle was against the stop. Waited an hour or so, the needle was still against the stop, then ran vacuum pump for an hour before charging.

Re: 99 two door Tahoe AC help
 

I have a 99 Tahoe 2dr and the capacity is 36 oz of R134. If you put 2.5 cans, that’s only 30 oz.

http://www.techchoiceparts.com/refri...et-light-truck

Re: 99 two door Tahoe AC help
 

I was using this chart for pressures, the low pressure is on the upper end for the temperature range. When I began adding the last can it began to cool less instead of better.
I’ve got a different orifice tube, I’m going to evacuate the system replace it, vacuum it down, recharge and try again.