Turn off all power to the machine first.

Dilute your acid 1 part acid / 2 parts water inside of a spray pump.

Try brushing off whatever you can from the coil first.

Now spray entire coil with the acid until every part of the coil has as been covered.

Now we have to let the acid set for 3 minutes so go clean out that spray pump and refill it with pure water.

After 3 minutes has elapsed clean off all the acid with the spray pump full of water, or a garden hose is even easier if the machine is outside.

After coil is clean wait 10 minutes for any acid residual to fade. Then close up system and re-try in ac mode.

And move to the end test page.