Any idea what my A/C problem is?

We have been gone from home for a week and when we arrived back this evening, it was about 83 degrees inside... so the a/c was obviously not running properly. (I am in Minneapolis, BTW.) I checked around the furnace and there was some water on the floor underneath -- that has happened before and clearing an obstruction from the tube that runs to the drain previously took care of the problem. It did seem to be obstructed tonight so I blew it out and water is coming through it to the drain. But while looking around, I noticed ice on the pipes that come from the air conditioner unit outside running to the furnace. I checked outside and there is also some ice there. The unit outside is running and the fan inside seems to be working too -- but there doesn't seem to be much air coming from the vents.

So... if anyone would know... could a blockage of the drainage tube cause this to happen? Or is something else more likely (nd more serious) to be going on?

Thnks for any advice you might have... I appreciate it.

An iced up system could mean the system is low on refrigerant.

Thanks. I have a service plan and when I called tonight that's what they are figuring too. They said to turn off the a/c to thaw the ice, and leave the fan running. They will come tomorrow (amazingly) to check it out.

I had this problem recently, lucky for me I have a good friend who is an Hvac installer and service person. My compresor unit was low on refriderent,as soon as he refilled you could hear the unit start running under a load and then my wife had to start putting on her mittens again. Also have them check to see if you have a slow leak on the caps connected to the refill lines.

I did as the service folks said, turned off the a/c and left the fan running. Within a few minutes, the ice was gone. I had put the drain hose in a bucket to see what might happen, and the bucket filled up. Air is blowig strong through the vents now. I did turn on the a/c for a few minutes, but the air coming from the vents did not seem cool... so I suspect the freon is low.

Frankly, this setup is 20 years old, so I suspect a new one is in order.... it's one thing to have the a/c go out, another to have the furnace die in the middle of a Minnesota winter...

>20 years old

Off topic:
When was the last time you cleaned the outdoor unit?

Fine stuff can plug up the out door unit and reduce efficiency, but that would not have caused the icing problem.

Everyone should clean there out door units with a garden hose at least every few years to improve efficiency and reduce power usage.

Like others have said,.......plus the age of the system speaks to me.

You most likely have developed "pin-hole" leaks in the evaporator coil, with a resulting loss of refrigerant.
When this happens your Pressure/Temp relationship drops. When you hit a bit below 60psig on the suction side, your evaporating temp in the coil is at, or below 32 degrees. At this stage what normally would have gone out of your condensate drain begins to freeze onto the coil. As it thickens, airflow is reduced, which makes the situation escalate until you end up with a solid block of ice for a coil.

At this point, the condensate water, which is basically the humidity in your home, can't run down the aluminum fins, and into the condensate pan.
Whether you have a slant coil, or an "A" coil, the water starts to drip through the middle of the A/H unit, and lands on the floor, where it builds up, and runs out wherever it can.

The airflow from the grilles are greatly reduced, as all you are getting is the air that can bypass around the sides of the iceblock.

Other causes are a totally plugged filter, or a filthy evaporater coil.
I don't believe these are your issues, as you said airflow returned to normal after thawing the coil out.

Time for a new energy efficient system!

Thanks for the info, Marc. The service guy put in freon on Sunday and the system is fine. But, I realized I am playing with fire with a 20-year-old system. So, a sales guy just left the house and I have a new Carrier system being installed next week. It is one thing to have a/c go out -- inconvenient -- but another to have the furnace go in the middle of a Minnesota winter. Now I won't have to worry about that.

mntentman said:

Thanks for the info, Marc. The service guy put in freon on Sunday and the system is fine. But, I realized I am playing with fire with a 20-year-old system. So, a sales guy just left the house and I have a new Carrier system being installed next week. It is one thing to have a/c go out -- inconvenient -- but another to have the furnace go in the middle of a Minnesota winter. Now I won't have to worry about that.

Click to expand...

No problem sir!
You might be able to keep your current system running for years as it is, if you are willing to have a small amount of refrigerant added now and then.

Small leaks, that require attention say once a year or so,.......WILL turn into a much larger leak with time. Then it becomes a much more frequent issue, and you need to ask yourself how many times do you wish to be "hot", and clean up water from the floor.

As life usually is,........all works fine until the worst possible time,......that is when it goes out again!

You will save on your electric bill with a new system, and be covered by a warranty.
Get at least three quotes, and unless you know the contractors, do a check on the BBB site for the one that you are choosing to go with.

Also, if MN is like here,........you can look up the license history of a contractor, and see if he has been fined, and such.
Yes, I dispense this info, because after 17 years, I have never had a complaint filed.

Good luck, and I think it wise to "bite the bullet" now per se.

Only warning I have for you,.......I hate contractors that use a "salesman".
Take that for what it is worth, but I surely stand by the 3 quote minimum.
Building is dead, and many contractors will be running to your place to give you an estimate,........use it to your advantage.

Edit: Looks like you have signed a contract already,......sorry for all of the above.
If you are not comfortable you have three days to cancel a contract as a consumer.