I have an Amana 13 Seer 2 Ton that has been installed in my house for three years. When I turned it on this summer I discovered that it was not properly cooling. I had three techs come out. The first and third provided the same explanation.

-The first tech that came out stated that there was contamination in the system from an improper installation of the unit by the builder's subcontractor. He recommended complete evacuation of the contaminated R410A and charge with new R410A.
-Builder's subcontractor stated that there is a possible blockage in coil, evacuate system, remove orifice, clean, replace coil if blockage is in coil. He planned on using same 410A that was originally in system.
-Third tech stated that contaminant in system, pressure does not indicate restriction in coil. Recommended recovery, flush, check piston, clean piston, replace filter drier, pull deep vacuum and recharge system.

I'm tempted to believe that there is a contaminant in system based on two techs stating this, but the builder's subcontractor repair recommendation concerns me because what if that is the problem?

I am hearing flashing outside when the unit has been running if that is of any help.

Any ideas, or thoughts on a similar situation you have encountered? I would love to have my house cool again. Thank you in advance.