Twee I would get a second opinion. Leaks at a valve are usually easy and relatively inexpensive to repair. Evap coil leaks In an air handler can be another matter entirely. Standard procedure when adding refrigerant is to include dye especially when tech did not attempt to find the leak. Let the system then run for several days and return to check coil to locate leak with proper tools. Was dye inserted? Do you even know? Yes, evap coils can be replaced in an air handler. However, usually this s not cost effective due to the expense. I assume air handler is out of warranty. IMO

"You can't blame them since the probability of having a leak is high. They don't want to deal with the call backs." What do you mean the probability of having a leak is high? If there were to change the inside coil and leave the old condenser, the old condenser will likely start to leak? I have the home warranty paying for the coil, but I would be paying for the condenser (if I replace). Frankly, if replacing the coil led to the old condenser leaking too, that would be good for me since I could get that replaced under home warranty too. Is that a common occurrence? Thanks again for the info. Also, any idea if the $950 to replace the coil is fair market value for a job like that? (that's what they offered me as a cash out from the home warranty company).

spray the coils with non-acid based coil cleaner, let it soak in for a few mintues, then rinse and repeat if needed. the water and cleaner goes out the drain. you should see 1 drain line coming off teh housing itself, then a second back up drain line coming off teh drip pan below the housing. both of these should be kept cleaned out, pour some bleach down them 1-2x a year. if your unit has the filter in the airhandler, then pour some bleach down the drains each time you are up there to change the filter. BTW, if the coil is extremely nasty you may require a pro to do the cleaning. they will have to evacuate the system, remvoe the coil, clean it, then reinstall and recharge it. NOT cheap, but is necessary in many cases.

For lazy technicians maybe, but to say replace the coil, when the leak is on a fitting, is sloppy work. Most coils can be repaired. If multiple leaks or advisories to replace are known, the reasons may offer a solution to replace the coil. If under warrantee, then replace. If replacing the coil, try to match the coil to get the best SEER available. Most technicians will not want to do this, because they dont know how to do the SEER comparison.