The bane of my life in the desert. Every July the ac fails like clockwork.

Hoping our ac experts might have an idea, or confirm my local guy before I spend yet another fortune.

I have an Amana condenser and I don't know what evaporator/blower, it was converted to 410A when they replaced the outside unit exactly 3 years ago.

1) The house was at 76 when we left today, about 111-113 outside. Returned home a couple hours later at 5:30 - no cold air! Inside temp creeping past 84. Both inside and outside units running but the fan air outside was ambient, usually here it's very hot after the heat transfer. But the cold side pipe was cold, but no icing outside.

Also, inside was blowing ambient, and not very hard. My first thought was icing, but doesn't seem to be.

2) Just before the ac guy arrived it suddenly started cooling again. Going back to about 78, and now 4 hours later after being on non-stop it is only 74 on the thermostat. The temp spread was about 12-13 degrees between vents and intake.

3) My ac guy checked the outside unit. And put in a new condenser. The old one was showing a "39" on his guage rather than 50, whatever that means.

4) He put 2 lbs of freon in, but now the temp spread is more like 8-11 degrees and has been at 74 for two hours. Also the low guage is showing 150psi which he says is the max.

Our house should be an icebox - so it's not the freon.

5) The "superheat" is showing 21, but he says should be 10, and the install paper shows 10. Whatever that means.

6) He now thinks it may be a "piston" or a "metering device" in the inside unit (located in the attic). He worked past dark and was nearly getting sick from the heat so he's coming back tomorrow when it's hot (hotter...) to see the numbers before removing possible excess coolant.

My days of climbing into a 140 degree attic are over so I have to trust the ac guys. I still think it might be freezing the coil, but don't see how that is possible with a full freon load.

So - I guess my question is... any ideas? What is this "meter?" And "piston?"

This is a straight ac, not a heat pump. Uses a gas heater.

We are ALSO running our two portable emergency ac units and fans - and still at 74 degrees inside.

I believe he's talking about the AC throttling device which controls the flow of fremon located in the air handler? There are typically two types. Capillary tube or thermostatic expansion value.

I've had issues with three of these the last year. Two of them had clogs in them. In the other case the AC guys from two companies couldn't diagnose the problem. Very similar to what you described.

The third company fixed the problem. Apparently there is a standard reading you get when one type of expansion valve is used and a different reading if the other type is in the unit. Most units have the more popular type. So they thought their readings showed all was well with the fremon levels. Turn out it was charged to match the wrong type of valve. This company adjusted the levels appropriate for the expansion valve the unit actually had and solved the problem.

Hope that make sense. I tend to absorb what I learn so I have some clue if they know what they're doing or not.

I think your AC guy knows his stuff.

Replaced condenser... you mean capacitor. If it is rated 50 and reads 39, time to replace. It will cause the compressor to run "sometimes".

And you changed refrigerants 3 years ago... were the existing lines flushed or replaced? If not, it is likely you have some small piece of trash stuck in the metering device indoors.

Hi, thanks for your insights folks. We are currently STILL waiting - he can't get back until like 7 tonight.

Currently the ac is only blowing about a 3 degree spread - and we have our auxiliary units running - temp is slowly creeping up, from 70-76 now and 113 outside.

Gevans - yes sorry, meant the capacitor.

I "think" when the system was partly replaced in 2016 they may or may not have done it right. It has never really had the spread it should have had like new we only got about 14 degrees not the 20 or 22 you'd think. But it still keeps the house cold, evening high heat. Last summer we hit 127 unofficially.

Arrgh - STILL no AC. It's worse now I finally shut the main system off but I think it's destroyed. 2 year old $4,500 piece of junk.

Running three portables with three rooms sealed off and house is still 79.

AND my AC guy fell off his ladder today and is oxyed out says he'll try to come tomorrow.