I noticed my house wasn't getting under 75°F this weekend when I had the thermostat set for 70°F. Since I'd done a lot of drywall sanding inside recently, my first idea was to replace the filthy air filter. My first indication that the air filter wasn't the root cause was when the return didn't have enough suction to hold the air filter in place while I was replacing it. I went outside to look at the compressor unit and discovered the exposed portion of the refrigerant line running into the house was frozen, but the fan was still running. The evaporator drain line still had a steady stream of water coming out of it. After turning everything off and waiting for the line to thaw, I turned the thermostat back on. Cooler air came out of the vents, but it didn't seem to be blowing with much force, and it wasn't as cool as it should be. I went back outside and discovered the refrigerant line was already frosting up again. At this point it was already dark, so I turned everything back off and slept with the ceiling fan on.

Other random notes that may or may not play a factor: The AC unit had been sitting idle the past 3 days since we had nice weather in the mid-70's last week. I mowed the lawn next to the condenser unit the day I noticed it stopped working. ac unit copperHowever, I was bagging the grass clippings, so nothing should have been blown into the unit.ac unit is making noise Any ideas on the root cause of the icing and lower air flow? how to service ac split unitI wouldn't think the two would be connected normally. Is it something as simple as low refrigerant levels? I plan on going to look more closely at it after work today. What are some other things I should pay attention to? UPDATE: I checked the system after work today and decided to give it one more chance after I couldn't find anything wrong with it.

After a few hours, it had brought the inside temperature down from 80°F to 75°F. I periodically checked the refrigerant line for freezing, but it never got much colder than 60ish degrees. I think the root cause was the air filter, and that I didn't allow enough time for the line to thaw last night. UPDATE 2: Maybe I drew conclusions too soon - I just checked the refrigerant line and discovered frost on it again. The inside temperature was at 72°F while the outside was at 66°F. I think pumping warm air to a cooler outside temperature may have contributed to the icing, but I'm not completely sure. (And if you think I'm crazy for running the AC when I could just open the window, you'd think twice too if you saw how many bugs swarm my porch light and windows every night. Dozens of them somehow find their way past the screens if I open the windows.) I plan on running it again tomorrow during the day and monitoring the refrigerant line temperature every few hours. If it freezes up again, I think I'm going to cave and call a repair guy.

UPDATE 3: I totally forgot to follow up on this. It froze again, so I called an HVAC repair guy. He checked the system, added refrigerant, and problem solved. I think the bill came out somewhere around $150 for the service call fee and refrigerant costs. You may be looking at the problem backwards, the freezing lines could be a symptom of the problem not the cause. Start by looking for blockages in the system that would cause lower air flow / heat exchange. Basically if the system cannot exchange the heat/cold, it will not function properly and could lead to over heating/cooling. Frozen lines could also be caused by high or low levels of refrigerant, so you'll want to get a service person out to check the refrigerant levels. Here is a really good image to visualize how it works. My A/C's frozen up before due to insufficient airflow over the evaporator coil. Turns out those $20 allergen-blocking air filters can slow down the air too much, so I switched to a cheaper one that doesn't block the air flow as much.

My A/C guy also told me that running the A/C when it's cooler outside than inside can cause it to freeze up in certain conditions like low airflow or low freon. My guess is a dirty "A" coil or blower wheel. There also may be a leak in the system. If it is the coil or blower wheel, clean it and there won't be a problem any more. If there's a leak adding freon will only temporarily fix the problem. The system should be leak free and refrigerant shouldn't need to be added. If the small pipe is frozen, the gas is insufficient. Call a service man to recharge some gas again. protected by Niall C. Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count). Would you like to answer one of these unanswered questions instead?Browse other questions tagged hvac air-conditioning central-air or ask your own question.

Why your city Home's A/C Freezes Up In SummerSummer’s coming (as hard as it is to believe right now) and here's an often cited scenario with the average your city area homeowner: They’re sitting in their house, minding their own business, having a bowl of popcorn and watching Netflix, when all of a sudden – that distant awful sound; They glance over to see the dog licking at a puddle that's gradually forming onIn a flash: Anxiety, stress, and that “how much will this cost?” feeling. How did the leak start?; Nope – the air conditioning equipment may be frozen. But, Service Experts Heating & Air Conditioning offers hope. The evaporator coil is the component of a central A/C unit that actually freezes. This component of the air conditioner transfers (evaporates) heat from the inside to the outside of your your city area home. reasons why the evaporator coil may 1. Airflow restriction, or 2. the ending effect is that the air conditioner's evaporator

coil cannot operate to properly transfer heat, and in essence 'overcools'The net effect of this super-cooling is condensation (that's water formation), and finally ice forms from that condensation as it cools below the freezing point. Yep, the A/C transformed into an old-school icebox. 1. Turn the unit completely off at the thermostat, and don’t try to thaw the system by increasing the temperature at the thermostat. sure the A/C system is completely OFF. 2. Confirm that there is nothing restricting the airflow to theReplace the furnace or air handler's filter along with any return airOpen all the registers completely and ensure that they are not obstructed by furniture or drapes. 3. Call Service Experts Heating & Air Conditioning. The air conditioning system needs to be inspected by a NATE-certified professional to ensure there are no refrigerant leaks or damageSimply schedule a Performance Inspection or Repair Diagnostic online, or call to talk to a live body right away.