Obstruction/Wrong Metering Device or Low Charge?

[samskaff]

I have a set of "no-leak" gauges I used when I was an automotive technician. I know how to get the data. I do not know how to diagnose home HVACR nor do I want to work on anything above 12 Volts. I also do not have any interest in messing with refrigerant other than the basic car refill can. I wanted to try to have a better idea of what, if anything, is wrong before I call a technician out.

Here is where I am.

R22 3 ton 10 seer Goodman unit in 1,400sf home (oversized)
Unit coils are clean & filters are not bad.
3.5 ton evap coil replaced three years ago with unknown piston (is that what it is called in home stuff?).
Ambient Outside Air - 79º
Ambient Inside Air - 74.5º

Condenser Readings
Suction Line Pressure - 40-60psi or 20-33º Hunts around
Suction Line Temp - 55-64º (Moves with suction PSI) using kitchen thermometer under insulation
Liquid Line Temp - 99º using infared temp gauge
Liquid Line Pressure - 190-220psi or 100º-107º
Air leaving condenser- 98º-103º (15º increase & 8º subcooling)

Evaporator Reading
Return Temp - 74.5º
Average Air at Register - 62º

Any idea why my franken-unit is hunting and not cooling air across the evap coil as effectively as it should?

Attached is a diagram I was going to send to a family friend for advice.

[Shophound]

I would invest more energy in looking for a competent technician than in trying to pre-diagnose your system for him. If you get a sharp tech he'll nail it on the first call. Once you find a guy like this, reward him with repeat business and maintenance calls, as sharp techs in this field are not a dime a dozen.

[beenthere]

While you may only be interested in what is rong for personal satisfaction.

Telling you is also info for DIY, and not allowed.

[samskaff]

Here is my problem. Just like in cars, they are great tech and bad techs. If you know nothing about cars it is very hard to tell the good from the bad until it is too late. I cannot change a metering device or add refrigerant so I promise you it is not DIY. I also have no interest in servicing my unit other than cleaning the condenser coil and changing filters. How can I tell if a technician is competent if I do not know what a good technician looks for. If you are here, reading this now you are more likely than not a good technician based solely on the fact that you want to learn more and improve at your profession. The guy who replaced my evap coil seemed competent until he refilled my system with refrigerant based on the sound of the compressor and by that point it was too late. Can you see why consumers who want to get more educated can get frustrated? Angie's List is great for Sally homeowner, but does he/she have any idea if the technician properly did anything other than showup ontime and look clean. A painters work is easy to judge, a carpenters work is easy to judge, a technician of any sort (car, hvac, computer etc) is much harder to know if they are doing a good job unless you have some basic framework of what they should be doing. So that is why I am reaching out. Sorry for the DIY post :(

[trey r]

Sorry we don't diagnose them on this site. Call a reputable company, even though I don't do much with the new electronic cars I can still tell if what the tech is telling me is BS or not.

[gasguy]

Ask friends/relatives who they have used and been happy with. Not that I'm encouraging lying, but maybe ask the service company to send out their senior tech as you have had bad experiences with previous techs. Mentioning you're interested in getting a yearly maintainance agreement if satisfied with their service may help make sure you get an experienced guy, but only do this if you will go through with the PM agreement. If you don't, you may find them 'too busy' next time you call!