Almost sounds like a complete restriction though it's not pulling into a vacume. Can you see any places where ice or frost is developing on the lines or indoor coil?
Both service valves are open- right?
Was a liquid drier installed at the indoor coil?
I would start at the indoor coil and make sure the screen is not clogged, then test the TX valve.

well now exactly how much refrigerant did we put in? and exactly how did we TAKE IT BACK OUT?

i would say the compressor is good due to the fact of the difference in pressures.....did you kink a line when installing the lineset? Check the liquid line dryer also. Should you of taken on this job not really knowing what you are doing?

daddo:
There is no ice or frost anywhere along the lines or coil. Both valves are open, although one of the valves required tweaking with to open fully. We did not install a liquid filter dryer and the screen is not clogged.
dnt1:
The unit came prefilled with 96in of freon. The required amount for a full unit was 116in for 15ft of line (which is how much there was). We added the required amount of freon. We then added a little more, due to the fact that the gauges were not responding as they should (only up to 120in). We took it out by reclaiming it, of course. How else would you take out freon properly?
jeffnette:
The difference in pressures was the same with factory installed freon, with recommended amount of freon, and with over amount of freon. A kinked line was the first thing we thought of. We removed a couple pieces of line and replaced them with 90 and 45 degree connections (the kinks were so small they were more like small bends). As I stated, there was no liquid filter dryer installed. As for your comment that I don't know what I'm doing, do you know what the problem is? I checked all possible problems. I did subcooling and superheat. I leak tested all connections. I replaced any possible kinks. I even double checked the wiring. I know what I'm doing, I have simply never come across this problem before.

Did you check the factory installed liquid line filter? Just because it is new doesn't mean that it is not clogged.
I tend to disagree with you on your knowledge of the installation due to the fact that why would you even check superheat when your pressures are what you say they are? Don't take this wrong but maybe you bit off a little more than you can chew.......

Ok, I will state this again..........there is no liquid line filter dryer on the unit. It is a Tappan. The liquid line filter dryers need to be installed by the tech on these units. After I vacuummed the unit (to 250 microns) I opened up the system and the pressures were at 170 liquid and 25 vapor. That was when I did the superheat and subcooling to try to determine how far off I was. Your attitude is completely unwarranted and unless you have any helpful information, I would appreciate if you would curb that attitude.

No attitude here, just stating the obvious. Your post speaks for itself!

Since the head psi is not very high, I am thinking a restriction that is not allowing but little flow thru the liquid or hot gas side. I have had one (that's 1 only) muffler completely clogged in the outdoor unit 10 years ago in a janitrol unit which caused a problem. You might check that. You may have to make sure the service valves are really opening by blowing thru them as well.
Open the liquid line outside and inside and blow pressure thru it to see if there is a restriction. If not, do the same with the suction line.
Personally I think the cap tubes or TX valve is restricting the system.
If it's cap tubes, heat the tubes with a torch some while the unit is running and see if there is a psi change- this will clear any waxed tubes and allow the "filter" to trap it. If it's a TX valve, heat the bulb up to see if there is a psi change- if so- replace the TX valve, if not, the valve could have what we call a dead head- replace the TX valve.
When installing a TX valve on a evaporator that also uses a piston- make sure the piston is removed. I would go ahead and install a liquid drier at the indoor coil no matter what I found.
The failure of the cap tubes or TX valve may have been the reason for the system failure in the first place.

what are- amp draw, refrig line sizes and linear length,(i dont think ive EVER seen a 15ft lineset) indoor coil size, type of metering device?
if there was a drier id say it might be installed backwards or you didnt purge with nitrogen as you welded your joints and got some trash on the screen at the metering device. (btw you should really put a drier on it)
sorry bud, but not installing a drier kinda screams inexperience to me as well.
or as daddo said maybe you stacked metering devices and the piston needs to be removed.
when you opened the first service valve on the unit did you notice if the other, still-unopened, valve's gauge pressure came up close to equalized?
does the unit pump down when you close the liquid valve?
if so, does it pump down quickly? you would think a 2.5t system with 15ft of line would pump down in a jiffy.

did you use rigid copper to tie the unit in?
if you did, did you take the rubber plug out of the end of it? (stupid question but ive seen an experienced guy in a rush leave the plug in it and melt it as he welded the joints creating a MESS and restriction.)

I havent seen it first hand but have heard of moisture freezing up near a txv partially clogging it.
500 micron is prefered, not 250.
you may not have enough refrigerant in the system. "116in of refrigerant"? is that some kind of metric system im not aware of? do you mean 116oz? who knows, its hard to troubleshoot over the net. keep looking, youll find the problem. either that or call a different tech that CAN be there with you to offer a different perspective.

This sounds like a blocked solder connection? I have seen bad joints several times that were almost impossible to diagnose.

The compressor sounds ok, but the low side only at zero sounds like a partial block. Do you hear rushing fluid anywhere? Even at the expansion valve? Anywhere could be a sign of reduced flow? Once again zero sounds like partial flow, not totally blocked flow.

Wow, well I do greatly appreciate all the advice. However, I've already figured out what the problem is. I worked on the unit yesterday for another 4 hours before finally realizing what it was. The TXV is bad. When I first started working again, I opened all the connections to make sure there wasn't a blockage from the soldering (which there was, but I fixed it) but still wouldn't work. So I redid the solder yet again to make sure I didn't cause the same problem I just fixed. Still wouldn't work. Checked everything else that could possibly have been wrong with the system, and found the bad TXV. Thanks for all the advice though.

So here are the two choices. 1: TXV was no good originally and that killed the compressor "OR" 2: TXV got killed in the process of brazing in a new compressor using sub standard procedures.
Vote now audience.,, I say 2, anyone else? :-)

if it was a new system i'd probably vote 2, but since the old compressor died im gonna give him the benefit of the doubt and vote 1.

dont forget to install a drier after you install that new txv. ;)

You already know my answer.....2.

I'll vote # 2. Could be that the torch accidentally brushed
by the bellows or the gas bulb. BANG. So much for the
T.X. The heat blows the needle off the seat or seals the
suction side but allows a small amount of leakage. HMS-HC
Is this an external or internally equalized valve ?

Back off bob, just trying to take the dullness out of this forum. And yes, I have screwed up on occasion, but I was smart enough to figure it out and know what to do about it to cover my behind. We all learn from our mistakes,, geez,that must make you another Einstein!:-)

bob brown said; "I am sure all of you have inadvertently killed a component at one time or another."
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You can't prove that!! :)