Our Central A/C has been blowing warm air for about the past week or so. I have tested with a new thermostat, completely cleaned the outside unit, cleaned the evaporator coils/fins, and tested continuity and voltage on the wiring harnesses. All components appear to be running properly, although I have very little knowledge of A/C systems. I finally decided to fork out the cash for a service call and the technician came to the conclusion that the Expansion Valve was "stuck" in the closed position. The system is still under a limited warranty for parts and he offered to replace the valve for a fee of approximately $400 for labor costs. That price instantly raised a red-flag for me so I declined, paid him the standard service call fee and sent him on his way. Like I said before, I have little knowledge of A/C systems but I felt the small service call fee was reasonable to be cautionary and do some researching first. Since I am a Navy Aviation Electronics Tech, it is my nature to at least attempt a fix on my own with as little resources and money as possible; we're no strangers to launching F/A 18's into the sky with duct-taped wings (just kidding... just kidding). So after doing some extensive searching on the internet for my problem I am still at a dead-end. I have read opinions that many techs can falsely diagnose the TXV as probable cause of failure. Apparently the indications of a faulty TXV are similar to other components (sensor bulb, among others, whatever this is). So I am seeking a possible "quick-fix" solution until I can afford to replace the component or even a solution that can fix it permanently without having to pay someone to evacuate the system and replace the valve. Is there any "myths" out there I can try? I'm thinking in terms of the potato to remove a broken light bulb theory or toothpaste to repair a scratched CD type of theories. I was thinking about turning the heat on for about an hour, or even turning the A/C on and blowing on the valve with a hair dryer or something. I am pretty desperate. Please help if you can, I am in TX and my wife and kids are starting to get cranky and it is dangerously hot this time of year.
Thanks in advance!
Justin

Unfortunately, there really is no "quick fix" if the expansion valve is indeed stuck closed. Possible scenarios: 1) The sensing bulb, capillary tube, or diaphragm have leaked the vapor charge and the valve is front-seated. 2) The system is contaminated with moisture which is collecting & freezing in the expansion valve. In this case the system will operate for a short time, then start "pumping down". Observing pressure gauges with system running will reveal this problem, and a moisture test is a recommended follow-up. Replacing txv will not correct this condition; recover refrigerant, install liquid line filter-drier, evacuate & recharge system. 3) Valve inlet strainer clogged. Like #2, system will "pump down", but this will occur immediately. If moisture contamination can be ruled out, refrigerant can be pumped down & isolated at outdoor unit (if equipped with service valves) to allow repairs to be made without the need to replace charge. 4) Particulate matter in valve mechanism. In a few RARE cases I have gotten lucky with this one: carefully tapping on txv caused mechanism to dislodge & system started working again. If this measure solves the problem, proceed immediately to the nearest lottery agent.

It looks as though you are at the point of needing a professional, first of all to verify that the expansion valve is your problem, not all service people are as knowledgeable as KC13 and trouble shooting a txv takes experience, replacing one also requires a set of gages and possibly torches and the ability to pump the system down or recover the refrigerant.
When you call for this repair, ask for approximate price of replacing the txv and make sure they check it first before just replacing it. Good luck, Mike

One way to check the TXV is to have a glass of Ice water and a Glass of Hot water and a set of gauges, connect the blue hose to the suction line and disconnect the bulb from the suction line, watch the pressure of the suction line for several minutes, then dunk the bulb into the Ice water and hold it for a while as you are doing this look at the pressure gauge, there should be quite a change if the bulb is still charged with freon, then do the same thing with the hot water and watch for a change in the pressure in the other direction. If you have changes I don't think you problem is with the TXV.

My liquid line is cold

Is the cap tube going to the powerhead broken or rubbed out?