Air Conditioning - What is the consensus on when it is quite hot out at the condensor unit?

I was doing a faucet repair at a condo yesterday, that faces southwest, but shades were all drawn. 94 degrees out and sunny, beating down on the southwest side of building condensor(the only place they could put it).

A non-running condensor next to this one, from the condo next door, was 120 degrees F when I infrared gun thermometer aimed down on the stationary fan. And the rockbed the unit sits on was about 113F.

The lady's cooling output at a register was 'only' 61 degrees, even though I had just pulled my trick of opening up the furnace blower door to let in about 65 degree cold basement air, which was really being drawn in. Yet the output at the register upstairs was STILL only 61 degrees F, even after I took the 77 degree return air grill temp out of the mix, and switched to the 65 degree basement cold air return temp instead!.

Besides a refrigerant leak, could it be possible that during super hot days with sun beating down on the condensor unit area, that the heat from the heat coils cannot be dissipated well enough, especially if it is humid out to boot (which it was!)?

This new thread was started by me after I read a thread by erik2282, whose a/c is not cooling well in Texas, and hereto, there might be similar issues perhaps with too hot/humid at outside condensor?

If I'm understanding the Q correctly, sure. The condensers job is the get rid of the heat picked up by the freon. If the tubing and fins are very hot, that makes the job even harder.

That is what it would seem like. Even us humans, when we perspire in hot humid weather, cannot transfer the heat as well.

I did have the opportunity to pay her a visit today and she was home and said it be okay if I temporarily run her a/c for a test. It was only 82 out today and cloudy, but very humid. The a/c was still only putting out 61 or 2, at that same register, even though the cold intake is only about 70 degrees. This just is not looking too good. I now suspect that some of the refrigerant must have escaped in it's 22-24 year age. It does blow out the registers nice and forcefully.

I'm going to test some of the other 8 places there that have the same identical brand and sized units, to see what they are all putting out.

I suggest washing out the condensing coil from the inside out. The cleaner the better.

I'll take a closer look. But from what I thought I was seeing without ducking down - it looked clean. But I'll check it out. There are no trees nearby, like cottonwoods, or anything that blows onto the lush landscaped manicured property from elsewhere. And nothing is in the rockbed - but rocks. Not even dead grass.

with out both coils being clean you no nothing.

If the air is coming out the registers forceably I believe the indoor coil won't be real dirty. If youre low on freon you probably are showing some frost either on the copper line leaving the condenser or where it enters the indoor coil.

Sherlock Holmes

Condensor coils are strictly a sensible heat exchange process. The RH of the air going thru the condensor coil has no bearing on it. The radiant heat coming from the sun is negligible. What really counts is the cleanliness and integrity of the coil and the temperature of the outside air.

The coil may look clean but I assure you, unless it was cleaned last season its not.

As far as your original question, the sun beating down on the unit etc. really has no bearing on heat transfer.

I have to disagree. Heat transfer with a CU thats sitting in the sun is handicapped. That's why good builders don't put them on the west side...hot setting sun.

Hmm, well, argue away then :D

I was at rich lady's a/c yesterday and get this: Like my open furnace blower door experiment(I love experiments) where I allow cold basement air into the evaporartor coil, just like at the condo I am speaking of here - ------at the rich lady's house, she must be having only sub-70 degree F temp drawing into the furnace filter, and yet output of the a/c from a register is only 59-60!

Is this going on because perhaps both of these units (the condo and the rich lady's house) have lost some charge? Or is it because of a law of physics that says the colder the air is that is entering the blower filter, the less the heat transfer? And the rule of thumb that you should see a 16 or so degree temp drop might no longer aqpply? That that rule of thumb applies more at hotter temps because heat transfers more rapidly between hot and cold than it would between cool and cold? Is that maybe what is really going on here?---why I am not seeing even colder register temps?, even though I have cold basement air being drawn into the mix?