A/C unit froze up solid

Melensdad

Jerk in a Hawaiian Shirt & SNOWCAT Moderator
Staff member
Well its HOT inside my house.

Its HOT and HUMID outside my house.

Noticed the house getting warm. Didn't feel much airflow through the ducts. Went outside and noticed ice starting to form on the outside unit.

Came back inside, turned the A/C to OFF. Turned the fan from AUTO to ON.

Called my local cigar smoking HVAC guy, caught him at his condo in Florida watching the sunset over the Gulf of Mexico. He told me to go pull the filter unit too, so I could increase the airflow, which would help melt the block of ice that has apparently formed on the coil inside the ductwork. So now I have a nice wet floor while the ice is melting into a puddle . . . fortunately there is a drain right there so the mess is not too bad.

He called his shop for me, service tech will be out in the morning.

In the mean time he told me to let the fan run with the A/C set to off for several hours to allow the block of ice to melt. So I'll flip it back on at midnight so we can sleep tonight. Then off again about 6am, still leaving the fan running, so it melts again. Apparently the service guy can't really do much if its a block of ice.

I'm down in the family room (lowest/coolest part of the house). Wife & daughter are up in the bedroom (highest/hottest part of the house).
 
Bet the A coil is plugged up with dust and dirt. Icing is often caused by poor airflow across the coil. It shows up quick when the humidity goes up. Do you have bushes tight up to the outside unit? They need a good 10" of clearance to plants to allow adequate air flow across the outside coil also. Mine is pumping gallons of water from the condensate on days like this. I change my filter about every 10 days as well. Need to buy another case of them soon.
 
What would happen if you switched it to heat for about 30 minutes?

You made me check mine... It's so cold in here all the lower level windows are covered with dew (on the outside).
 
Bet the A coil is plugged up with dust and dirt. Icing is often caused by poor airflow across the coil...

That is what I understand.

My filter is one of those big box type that can last a year. It actually looks pretty good. Pre-filters look pretty good too. But I pulled them out anyway to allow for more flow.

My guess is the coil is clogged up with dust. Its going on 19 years old. The unit is undersized too, which makes it hard for the system to keep up with the heat on very hot sunny days (like today).
 
A year? It must pass everything but pigeon feathers.:yum: I run high allergen filters and change them at least 20-30 times a year. I can tell by the sound of the fan and ductwork when it needs done. Costs me about $62 for 2 cases of them and it is less hassle than cleaning the coil. Is your drain line clear and flowing well?
 
My walk in meat cooler does the same if I run it to cold the first day. lots of moisture in warm hanging meat and no defrost cycle to melt the ice.
jim
 
A year? It must pass everything but pigeon feathers.:yum: I run high allergen filters and change them at least 20-30 times a year. I can tell by the sound of the fan and ductwork when it needs done. Costs me about $62 for 2 cases of them and it is less hassle than cleaning the coil. Is your drain line clear and flowing well?
I run the same filters as Bob.

$62 won't buy 2 filters. :(

Info on the filter.

http://www.discountfilters.com/air-filters/generalaire-12758-2-pack/p112065/
GeneralAire AC-1
A furnace-mount air cleaner uses a filter to trap and remove airborne pollutants and allergens. The GeneralAire AC-1 replacement filter earns a MERV 11 rating. It reduces allergens like dust, pollen, pet dander and mold while capturing odors from cooking, smoking, pets and the bathroom. Accordion-style media expands and fits into the frame. Existing pleat spacers increase the filter's surface area and filtration capacity. When replaced every six months, the filter provides clean and healthy indoor air.

MERV 11
removes dust, pollen, mold, pet dander and odors
accordion style filter media expands to fit into th's frame
use existing pleat spacers for an evenly spaced and efficient surface area
replace every 6 months
 
FWIW the AC unit thawed out and is running ice cold right now.

The repair guy is coming in about 30-45 minutes. He called almost an hour ago from the shop.

I'm planning to shut the unit off again shortly. They want to make sure that the unit is not a frozen block of ice when the technician shows up. Its only been running about an hour total, but its amazingly cool and comfortable in the family room so Melen, the dogs and I are all hiding out in here with the vents WIDE OPEN.

In the mean time I'm getting the house as cold as possible. :letitsnow:
 
I just replaced my AC unit and heat pump with a new Trane high efficiency. The outside unit was leaking in the coils (could see oil on side of unit) and Trane had a good deal going on with 0% financing for 36 months. Figured I would use their money for free instead of mine. The biggest thing I noticed was how quiet the new outside unit is.
I bought one of those portable AC units for times like that or when the power goes out as my generator can't run my central air but at least I can keep one room cool to sleep in
 
I'm back up and running. At least temporarily. We have several freon leaks. And there is a bad seal outside. And the unit is 19 years old.

Well it looks like I may be replacing the AC and the Furnace for a new high efficiency unit?

He's going to get me some prices. Basically wants me to step up in size to a 5 ton unit that is more efficient. Says it will do a better job overall, and he mentioned that they are MUCH quieter than what we have now too.
 
I'm back up and running. At least temporarily. We have several freon leaks. And there is a bad seal outside. And the unit is 19 years old.

Well it looks like I may be replacing the AC and the Furnace for a new high efficiency unit?

He's going to get me some prices. Basically wants me to step up in size to a 5 ton unit that is more efficient. Says it will do a better job overall, and he mentioned that they are MUCH quieter than what we have now too.
Bob I know you are thing what the he11doesa guy from up at the arctic circle know about a/c. well I learned a lot real fast when stationed in Iraq. reading your complaint a low charge was my first thought. if you have over evaporation on the low pressure side your evaporator is going turn to a block of ice even in lower humidity as I remember right we ran about 30 lbs of differential pressure between the high and low side
 
I'm not a HVAC tech but have a couple questions/thoughts.

If the issues/leaks are in the heat pump and you install the same size heat pump, do you need to replace the furnace/air handler inside?

We put in an Amana 5-ton unit (including the furnace side) a few years ago. It is a lot quieter than the circa 1990 Lennox unit that the house had.

If you replace the furnace/air handler, get one that has a low-speed fan option. You can then set it to run on that speed 24/7 which helps a lot with temp and humidity balancing across all floors of the house. We do it and have never since needed to run dehumidifiers in the basement.
 
Did he do heat loss/gain for your house? Did he calculate duct size to see if your old stuff can move enough air?
 
Did he do heat loss/gain for your house? Did he calculate duct size to see if your old stuff can move enough air?

He spent 2 hours looking at the ducts, crawling around, inspecting runs, muttering "he's f****d" under his breath.
 
New, larger, more efficient unit will be installed tomorrow.
What brand do you currently have and what are you replacing it with? I'm at 15 years with mine and I'll probably be needing to replace in a few years also.
 
I'm back up and running. At least temporarily. We have several freon leaks. And there is a bad seal outside. And the unit is 19 years old.

Well it looks like I may be replacing the AC and the Furnace for a new high efficiency unit?

He's going to get me some prices. Basically wants me to step up in size to a 5 ton unit that is more efficient. Says it will do a better job overall, and he mentioned that they are MUCH quieter than what we have now too.

It is okay to have an A coil with a larger rating than your outside unit, but not the other way around. I have two 3 ton units (both with 4 ton A coils) and one 2 ton unit with a 2 1/2 ton A coil. If you push too much through a smaller A coil, they will freeze solid every hot day when they run for extended periods of time.

I had to work on my 2 ton unit (that cools my office) yesterday because it was just not working at all. I found it impossible to do payroll when it was 94 degrees in my office. My Mac shut down twice and I noticed the entire aluminum case around the all in one monitor was so hot it would burn you. So, I found that the fan that draws air through my condenser was not working after a brief inspection. Since I didn't have the time to fix it and I don't call the expensive HVAC guys (I've installed all my A/C and furnace units) I laid a box fan on top of the condenser, blowing up, and it worked fine the rest of the day. I suppose I'll have to go buy a new fan today because my box fan on top of my A/C unit isn't a very good long term fix.
 
What brand do you currently have and what are you replacing it with? I'm at 15 years with mine and I'll probably be needing to replace in a few years also.

My Trane (American Standard) unit I just picked up a new fan for is 21 years old and is still working great. It's a 12.8 SEER (highest made when I bought it) so I'm in no hurry to replace it. I fully expect to get 25 years out of it before I consider the expense of replacing the unit. With the high price of copper now, if your line set is very long, that alone will add quite a bit to your bill. Line sets have to be sized to the unit. Going from a 4 ton to a 5 ton would require replacing the line set for proper functioning. I'm still getting a 22 degree difference between the air in the ducts and the ambient room temperature, and that is about all you can get.
 
I'm getting a Trane this time.

My original HVAC system was put in by 'the lowest bidder' and its been a constant issue for us in this house. I hired a well respected general contractor to build the house, but apparently he cut corners on HVAC and we've paid the price ever since.

About a year after he built my house he said I should have had 2 units. WTF?!? I relied on him to do it right.

In addition to changing the main system, upping the size, increasing the efficiency, we are also going to be doing some modifications to some of the duct work and utilizing a couple in-line duct booster fans too both on a long run of the air return and a couple air feed lines.

Oh, and if I pay ca$h then he will give me an even better discount. I already alerted the bank branch to have piles of it ready for me to pick up.
 
Good info Bob. My situation is much the same only I picked the HVAC and was running short on cash by the time I made that choice. While not the lowest this one was close. I have Janitrol Furnace and heat pump. Both have performed well with the only repairs being on the doo-hicky that replaced the pilot light on high efficiency furnaces. I've had to replace that piece 4 or 5 times but otherwise they have done a good job. But when I replace I will probably go with a Trane unit. Quieter would sure be a good thing.

I could use a duct booster also. I was not aware of those but will look into them.
 
Well I didn't spec out the HVAC first time around and honestly didn't know how to do it then even if I wanted to do so. I've learned a lot due to owning a bad system.

Problem with my house is I need 2 systems. I also need to start over with the ducts, but that would entail tearing out walls, ceilings, etc.

So I have to make due with what I have and that means trying to squeeze more air through the ducts that don't get enough. With lots of 90 degree turns and very long runs the only way to help boost air is to run booster fans.

Its a patchwork repair but about the only practical option I have.
 
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