[Rich-L79]

Tonight I noticed that the air was running and running but the temp wasn't coming down. I then noticed that very little air was coming out the vents. Near the interior unit I found the freon lines were dripping wet, so much so the floor around the unit was a puddle. I checked the condensation drain and it was not clogged. I then pulled the access panel and found the cold air exchange was frozen solid like a block of ice. The reason no cooling could take place is because no air could pass through the exchanger. I left the access panel off so the unit could thaw but I've never seen anything like this before. What could have caused the exchanger to freeze up like that? It looked like a freezer that hadn't been defrosted in 10 years. Is there a fix or is it time for a new HVAC system?

 

[PHX396]

Shouldn't need a new system. Are you sure the blower motor is working? If the blower motor goes out unit will just run and run and freeze up?

 

[pnugene]

Low Freon charge, due to system leak. Call a serviceman.

 

[Rich-L79]

Blower is running fine.

 

[floyd66]

It was running flat out for an extended period. Had no time to thaw out. Could be an undersized system or an unusual hot stretch.

 

[AJS]

Dirty air filter, low freon charge, indoor blower motor not coming on, contactor welded closed ( brings on the compressor and the outdoor fan motor), collapsed return air flex duct to start with.

 

[O'Man]

Tonight I noticed that the air was running and running but the temp wasn't coming down. I then noticed that very little air was coming out the vents. Near the interior unit I found the freon lines were dripping wet, so much so the floor around the unit was a puddle. I checked the condensation drain and it was not clogged. I then pulled the access panel and found the cold air exchange was frozen solid like a block of ice. The reason no cooling could take place is because no air could pass through the exchanger. I left the access panel off so the unit could thaw but I've never seen anything like this before. What could have caused the exchanger to freeze up like that? It looked like a freezer that hadn't been defrosted in 10 years. Is there a fix or is it time for a new HVAC system?

Your last sentence says it all. These systems have to "Defrost"...if it was running flat out it never allowed for frozen condensate to melt and drain. I had a system that did it all the time in the spring. I ran the A/C at times when it was not really hot enough outside. I did not want the windows open due to allergies. It ran fine in the heat of summer but would screw up from time to time just the way you describe when I ran it int he Spring.

Other reasons listed..low charge, blower motor not running at all (you seem to have ruled that out) or clogged filter(s) could be the causal factor. It is in the final analysis about the system not getting time to "thaw" the evaporator. Once the airflow across the evap is messed up for any reason (even just a thin layer of ice) it will just ice up more and more. The evap needs warm air flowing across it but it also needs to cycle on and off. If the T-stat is set asking for the temp to be too cold the system runs all the time and it will freeze but nothing will be wrong with the system. . Check filters, check t-stat, be sure of correct charge and it needs to cycle on and off regularly.

 

[BBimp]

My Impala had a termostat that disingage the comperssor when the evaporator gets too cold. you can install one on you system.
They also come universal and ajustable

 

[elcamino66]

After it thaws check the evaporator to see if it is dirty and clogged up. Mine did the same thing and that was the problem. My filter gets changed every 3 months like clockwork, go figure. A good cleaning fixed it.

 

[OLDED]

I had that happen in a new house years ago - turned out the intake was completely plugged up with blown in insulation that got in because the idiots installing the cold air return left an opening in the attic and allowed the cellulose to drop down into the coils. Had to spray water on the 2' x 3' block of ice in the middle of the night and clean the coils to get air moving through it again.

 

[Cam]

The symptoms you are describing sound just like what I went through 2 years ago with my 1970s York unit. Although my exchanger inside the duct was plugged with dust, that ultimately was not the cause. It turned out that it was low on refrigerant, but the type of refrigerant it required was no longer available. I ended up replacing the unit with a brand new American-made one, a Goodman. The new one uses a LOT less electricity and work very well.

 

[Rich-L79]

Well, I let it thaw and drain overnight and it seemed to be running well this morning. It cooled the house down in a little more than half and hour this morning. We'll see how it functions through the day today. It has been mildly warm, high seventies-low eighties, with high humidity so perhaps that's a contributing factor as well as a menopausal wife who keeps turning down the thermostat every time she has a hot flash.

 

[Dakenzie1]

The system will freeze up again. An a/c system that is working properly never needs defrosting. As previously stated there are numerous reasons that an a/c system will freeze and the system should be serviced. The fix may be quiet simple, yet if allowed to continue freezing up, could cause permanent damage to the compressor.

 

[CHELKAMINO]

I had an issue a few years ago like that, changed filter and cleaned out unit really good. Worked fine after that.

 

[Blownchevelle68]

Mine does the same thing from time to time. Usually what I find is the 3M allergen type filters get clogged quickly, this last one only made it about 3 weeks. I usually pull the filter and shut the system down but run the blower motor on to help thaw out the coil, then replace with a fresh filter.

Like mentioned above, it will freeze up again, probably yet today. If the filter trick does not work, I'd look forward to a service call and hopefully something simple like a recharge.

 

[Andy's Auto Repair]

Two things I know.

My neighbor has two rabbits.

And a pallet of the old school freon.

You don't neccesarily have to change the unit if it is low. Just got to find a guy who stiill has some old stuff laying around.

 

[LeoP]

Usually caused by a low charge, letting the blower fan run will defrost the coil, get a serviceman in there to check it out. If it is over 10 years old, maybe time for a new unit. good luck.

 

[pnugene]

The system will freeze up again. An a/c system that is working properly never needs defrosting. As previously stated there are numerous reasons that an a/c system will freeze and the system should be serviced. The fix may be quiet simple, yet if allowed to continue freezing up, could cause permanent damage to the compressor.

Frankie's got it right, a properly charged and operating AC system will not freeze up. The OP's unit will likely freeze up again until the malfunction is ID'ed and repaired.

 

[AJS]

My last job today was a blocked coil. Would cool somewhat at night but would run all day and not get below 80. Was also muggy inside. Didn't ice over but it would have soon. They probably haven't had an air filter in there in over a year. Carpeted apartment, three dogs, cat, and probably haven't cleaned or vacuumed in over a year. Recipe for a cooling failure. I had to climb up in the return to wire brush all that crap off of there. Wanted to vomit. Couldn't wait to get out of there. Packaged unit. An A/C system HAS to move the required air for its capacity or it will not operate at optimal performance. Will it work - yes. If you loose enough air flow it is going to ice up. For the OP, look for any oil stains. Most refrigerant leaks will leave oil residue. Kind of like a valve cover. Check service ports. Make sure caps are there, washers inside, and tight.

 

[joe2maine]

Got seven dogs in the house have to clean the evap. every few months or the air flow is restricted enough to ice the coil. The low micro filters help but clog fast.