I live in Houston, and had the compressor on my home A/C replaced four years ago. The A/C system on my home was original to the house, and was put in service in 1981. The guy who installed it told me that the evaporator would probably be going out soon, and I guess he's right.

A week ago, I came home to a unit that was running, but no air was coming out of the vents and the temp in the home was over 90 degrees. So I climbed up in the attic where the evaporator is located, and examined it. What I found was ice blocking the evaporator, so I called my A/C guy for a charge. It lasted a couple of days, but that's about it. So now, due to the lack of funds, I'm having to cycle the thing off and on to give it a chance to thaw out each time between cooling cycles.

I have a couple of questions about it.

First, why doesn't the system ever bleed down completely? There's obviously some freon in the system, or it wouldn't ice over like it does. If there's a leak somewhere, why wouldn't ALL the freon leak out, preventing any cooling at all?

And more importantly, is the evaporator a component I can replace myslef to save cost, and then have someone come draw down the system and charge it? And if so, what kind of business would I go to here to find an evaporator?

I'm really broke right now and need to save all the money I can.

Thanks in advance!
Wendell

 

No you cant do it yourself. What freon is there has to be pulled out and recovered by an EPA tech.
Now by running it some and then turning it off you are hurting the compressor. It can suck air into the system and foul it up.You can lose the compressor this way

Could be the leak is on the high side here so when it runs some of the freon get's out then but not when its off.

Yes a unit will run with some loss of freon but it get's colder that is where you get the ice build up on the coil. ED

 

Wendell:

Ed is correct in that you cannot repair this yourself and will do damage to the compressor if you continue to use it this way.

You first will have to have determined whether it is actually a leak or something else that is causing it to freeze up.
A dirty coil or plugged filter would have the same effect.

 

Well, doggie do-do. I was afraid of that. Not being able to do it myself, I mean. Didn't know about the compressor part of it though. Guess I'll just have to call someone out.

Thanks for your input guys. That's what makes these boards rock!

 

Wendell:

What you can do yourself is some basic maintenance to rule out a dirty evaperator coil.

You would have to open up the airhandler and remove some sheet metal to get at the upstream side of the coil.

 

I can do that, as there's plenty of room in the attic where the unit's located. So the way this thing is laid out is that there is a fan on one end pushing air through the unit. Next to that is the gas heater. Then the evaporator coil is at the very end before the air box splits the round ductwork out to the rest of the house.

Would you say that I need to remove the metal duct work between the heater and the evaporator coil for inspection? How about the heater coils? Any chance they're blocked as well?

Geez, I should be so lucky that this is all it is. I'll do the inspection before I call anyone out.

Cheers!
Wendell

 

Wendell:

If the fan pushes air through the coil you want to look at the fan side of the coil.
There are many ways of installing a coil so you will have to kinda just feel your way along.
A flashlight shone through the coil will give you an idea of whether it's dirty or not.
It sometimes will look fairly clean but is not.

The heat exchanger is not likely causing a restriction but another thing to check is the surface of the vanes on the fan.
A 1/8" buildup of dirt can reduce the fan output by up to half it's normal volume.

 

No kidding? Dust on the vanes can cause reduced air output? I had no idea. I've got a lot of dust on my brain, so maybe that explains the lack of output there as well! I'll check it.

I'm going out for a while after work, but if I'm not too looped when I get home, and I'm in the mood to, I'll climb up there and take a look at it.

I'll report back in the morning with whatever I find.

Thanks again, and have a great evening.
Wendell