I have a Goodman A/C and air handler. Yesterday, the airflow was greatly decreased when running the A/C. The thermostat downstairs read 78 degrees, but temp upstairs was over 88. A/C repair came and said there was a leak and evaporator coil needed to be replaced. They recharged the freon and left. Temperature in house remained the same. Problem came out of nowhere.

Question: what could have caused the lack of airflow upstairs and significantly diminished airflow down? Still blazing hot upstairs and downstairs won't get below 78. Also, evaporator coil is NOT freezing. HELP!

Oh and the dampers on ducts going uipstairs and down have been checked and are not closed. In fact I closed the downstairs damper completely to try and force the cold air upstairs and it did very little: low flow downstairs still, and very low flow upstairs. Blower seems to be running - could it be dying and slowing down?

Lack of air flow could be caused by dirty air filter, dirty evaporator, dirty condensing coil, fan not running up to full speed. I would have thought the tech would have checked these as well.If you have a leak in evap you are going to lose the ref they put in.

I changed the air filter at the register indoors, but can't find any other filters. The unit has a sticker that says there are no internal air filters. Supposedly, the fan is running up to full speed.

How would I check for a dirty evaporator or condensing coil? Then, how would I clean them?

You can clean the condensing coil with a garden hose. Disconnect power to unit and remove all grass etc. from it. Then hose it down from the inside out. May have to remove top to get in there. To clean evap coil properly you would need to remove it from cabinet. This requires recovery of ref. unbrazing lines and removing. Then you need to reinstall, rebraze lines pull a vacuum and charge properly with ref. Not a job for diy. You will need a tech to do this. But if you have a leak in evap and it's going to have to be replaced this is something not to worry about. Good Luck