stash-hdy,

If your outside condenser has light buildup on it you should be able to use a light spray from the hose to wash it off. If you have an oil & dirt, cottonwood tree buildup or more of a heavy organic buildup, there are "Coil Cleaners" which can be sprayed on to loosen the buildup. Then lightly hose the cleaner off. You can google "Coil Cleaner" to find a product, use a commercial grade if possible and don't let the cleaner stay on too long as some products actually etch the aluminum.

Cleaning your condensing coil typically is the best way to save energy dollars as A/C is the highest load.

Stay cool!

I use Simple Green and it works great on the outside fins.

Then spray it off with a hose. Make sure that you spray the water from the top, pointing downwards towards the bottom of the unit. Do not spray straight ahead, forcing the crud inside the unit.

"I use Simple Green and it works great on the outside fins."

Simple Green has a high enough pH it can corrode aluminum.

It is making it very clean by removing metal.

i see no one said how to clean the coil, just the condenser.
Is your furnace a up flow or down flow? Is the coil on top of the furnace,or under the furnace? If you try to use coil cleaner on you indoor coil you need to have a pan under the coil to catch all the water and coil cleaner. You do not want the coil cleaner to get on your duct work or on your heat exchanger. also be aware that a lot of these coil cleaners have a acid in them that you don't want to get on your skin or in your eyes. If your outside condenser coil has a lot of white fuzz in it, you do not want to put a water hose on it from the out side, that will only push the dirt in deeper into the coil. You need to to take the top off the unit and hose it from the inside out to push the fuzz out.
later paulbm

"If you try to use coil cleaner on you indoor coil you need to have a pan under the coil to catch all the water and coil cleaner."

The first problem can be even getting to the evaporator coil.
I have seen many that require cutting of the plenum to gain access.

There is already a pan present, the evaporator drain pain.
Just use some plastic to try and make sure the cleaner does not go all over the place and drips in the pan.

This is not garden hose territory.

You are right it is not easy to clean the indoor coil. I usuals raise my coil up about 8" from the top of the furnace
so i can out a clean out door under the coil. then i can slide a pan in there to catch the mess

The outside condenser had light dirt on it so I cleaned it with a light water spray. Will try to clean the indoor coil today. Got a spray that does not require water to clean off, will see how that works. Will see if I can put a pan under the coil anyway. Had my electrical supplier do a energy audit last week and he stated I had a lot of leakage on the A/C unit itself so I will also fix that. When I get finished I will call a technician to check the freon. Can't do that myself. He also mentioned that I had less than needed air temperature difference, don't understand that at all.

I cleaned the inside coil today, it looked very clean and the pan under the actual coil was wet but clean. Sprayed with the foam cleaner and did not wash off with water. The can said that was OK since the condensed water will clean it off. The secondary pan under the unit is very clean no rust. Did feel a lot of lost air around the ducts attaching to the A/C box. That will be tomorrow's job, too hot up there to work any longer today. Don't know how you technicians do it day after day, hats off. I taped the cover and sealed with the paste.

Any tricks on attaching the ducts to the box so they are sealed?

Taped all duct connections, I did find that the cold air return duct was not attached to the box at the bottom. I would assume that pulling in the hot air from the attic was causing the air differential not being to spec. Thank you for your input.

Will have a technician come to check the Freon next week.

There is a lot of work and time to check and fix the A/C. Will not wait as long again to have a technician check out the system.

Unit took almost 2 lbs of Freon, all is well
Thanks