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Home A/C problem


nurkvinny

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I've noticed the past few weeks that the larger of the two lines that go from the inside unit to the exterior unit will gather a large amount of ice right where it goes into the inside unit. Happens if it is very hot outside or we try to drop the inside temp more than usual (say, from 77 to 75).

 

Once I turn the thermostat back up or it cools off overnight to where the ac isn't running as often, the ice melts and leaves a large puddle on the floor.

 

House still cools but probably not as quickly as it used to. Likely cause(s)?

 

I'm sure I'll google it tonight but know there is some ac wisdom on here.

 

Thanks

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I had the same problem but my freon levels were fine. What's happening is your freon isn't warming up at your evaporator inside the furnace.. check that to see if it is also iced over. If air isn't passing through that (from the fan blower) the freon in the system will stay cold and ice up the lines. Turn off your A/C for about an hour and if you can, run the fan only. Also make sure your evaporator drain tube is draining the water and change your filter every 30 days with a high-flow one.

 

I bought my house a year ago and I've gone from zero knowledge to being a god damn professional, since M/I skimped out on my tiny ass little condenser unit. Mine is meant for cooling maybe a one bedroom apartment but they installed it on these 1800 sq ft cookie cut houses.

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Pulled the filter out first thing, it's only a week old.

 

I pulled the side panel off and it's a royal ice fest. Coils buried in ice.

From Google:

 

 

Control board failure: if the the HVAC/R system control board is defective it may not be sending the signal to the compressor to shut down when the thermostat has been satisfied. In that case at the indoor air handler / blower unit the blower fan has stopped (and on commercial equipment louvers in the duct system have closed) but the compressor keeps sending refrigerant to the cooling coil. The problem could be in the thermostat, thermostat wiring, or the control board itself may need replacement. Thanks to reader R. Hansen for this tip.

 

Cooling coil fan (the blower in the air handler unit) has stopped working. A bad fan motor relay, a bad fan motor itself in the air handler unit (some call this the "evaporator fan"), lost (or someone turned off) electrical power to the air handler blower, or even a blocked fan blade or loose fan blade on motor shaft or a fan blade blocked by ice (rare in most residential air conditioning system designs), or a lost, or broken fan belt (if your motor is not a direct drive unit) can cause coil frost formation.

 

The blower fan (air handler fan or evaporator coil fan) should run when your thermostat is calling for cooling. The motor could also be off on thermal overload or reset - see ELECTRIC MOTOR OVERLOAD RESET SWITCH. With electrical power to the blower unit off, see if the fan blade moves freely. If not the fan motor assembly needs repair or replacement.

 

Damaged cooling coil fins can also lead to evaporator (cooling) coil freezing: when the coil cooling fins are bent and crushed sufficiently to block a significant portion of air flow across the coil, icing is likely. See DAMAGED COOLING COIL for details on how to recognize and fix this problem.

 

Debris-blocked evaporator coils might lead to evaporator coil icing: When an air conditioning or refrigeration unit evaporator coil becomes sufficiently blocked with debris as to slow down the air flow enough, the coil may actually become so cold that the condensate forming on its surface freezes, completely blocking the coil. That's because the rate of release of refrigerant into the evaporator coil was designed with an assumption of a sufficient volume of air moving across the coil to keep it from becoming too cold. We discuss dirty evaporator coils in more detail at DIRTY COOLING COIL. Dirty or debris-blocked evaporator coils are caused by running the air conditioning system without an air filter in place. The coil will need to be cleaned to get the system working again. See DIRTY COIL CLEANING PROCEDURES.

 

Defrost control: A malfunctioning auto-defrost control or bad defrost timer control (less common on residential air conditioning systems)

 

Dirty air conditioning filter can block or reduce air flow across the cooling coil, leading to coil frost. This is the first component a homeowner should check since the fix: replace the air filter, is so easy. See AIR FILTERS for HVAC SYSTEMS

 

Dirty blower fan blades or non-functioning blower fan assembly: an air handler blower unit that is not moving as much air as it should will be blowing too little air across the evaporator coil. This is a less likely but possible cause of frost build-up on the cooling coil. See DIRTY A/C BLOWERS for details. Don't forget to check for a dirty blower fan itself - dirt can significantly cut airflow produced by the fan. See BLOWER FAN OPERATION & TESTING

 

The refrigerant charge is too low. If there is a refrigerant leak, the first symptom may be coil icing; but later as refrigerant continues to be lost, all cooling may be lost and the coil will no longer be frosted or iced over. In our opinion it's better to find and fix the refrigerant leak. See articles beginning at REFRIGERANTS & PIPING.

 

Refrigerant loss or expansion valve problems might lead to cooling coil ice-ups: an improper charge or amount of refrigerant in the system can cause frost build-up on the evaporator or cooling coil. Too-little refrigerant can cause temperature in the coil to be abnormally low, leading to icing. Really. We discuss the detection of air conditioning refrigerant leaks in detail at A/C REFRIGERANT LEAK DETECTION.

 

Watch out: air conditioning refrigerant leaks are not normal and should be found and fixed. it's better to find and fix a leak than to turn your leaky air conditioning system into a stop on your repairman's regular refrigerant delivery route.

 

Thermostatic Expansion Valve malfunction: a bad TEV or capillary tube that is not metering refrigerant into the evaporator coil at the proper rate can cause frost build-up or icing on the evaporator coil or cooling coil. We discuss thermostatic expansion valves (some call them thermal expansion valves or TEVs) in more detail at THERMOSTATIC EXPANSION VALVES.

 

Wall thermostat not working properly: a thermostat that fails to stop calling for cooling can lead to coil icing. When the set-temperature on the thermostat has been reached in the room where the thermostat is mounted, the thermostat should stop calling for cooling (or its switch should "open". But wall thermostats are so simple that unless someone has damaged the thermostat or operated it in a very dirty environment we don't find that the thermostat problem is a defect in the unit itself. More often it's operator error: the thermostat is not set properly, or it is set to a low temperature that the cooling system simply can not reach.

 

Watch out:Don't just try quickly and repeatedly turning the thermostat up and down. Some air conditioner compressors may have trouble re-starting against the head pressure of refrigerant in the condenser unit. So if you keep switching the A/C system on and off the system may stop on a thermal reset. If you suspect you've caused this just leave the air conditioner off for 15 to 30 minutes and then turn it back on. See HARD STARTING COMPRESSOR MOTORS.

If it slowly happened over time I would guess your fan is dirty and not blowing enough air. Is it blowing hard out your vents? (let the ice melt overnight first, then try tomorrow morning)

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Mine quit tonight. Bulging capacitor. Are most heat pump capacitors the same for 240v systems?

 

I bought a new cap, hooked it up correctly, and the fan was spinning backwards. I tried every combination of wiring and it either did that or sat there humming.. never worked right.

 

I bought a second one, different brand, with (iirc) a slightly different farad rating and it worked perfectly first try.

Yes, full force coming out of vents.

 

I just had my basement finished, so I am leaning towards drywall dust causing havoc (I replaced the filter 4 times over the 4 week construction period).

I'd guess it just needs charged then, which costs money.. sucks.

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I bought a new cap, hooked it up correctly, and the fan was spinning backwards. I tried every combination of wiring and it either did that or sat there humming.. never worked right.

 

I bought a second one, different brand, with (iirc) a slightly different farad rating and it worked perfectly first try.

 

I'd guess it just needs charged then, which costs money.. sucks.

 

 

 

FYI:

 

For HVAC parts, I use Grainger. http://www.grainger.com/Grainger/wwg/start.shtml

They sell to the public now and it's convenient and costs less than most other places. Nothing I've ever needed wasn't in stock.

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It's called research taking a little time.

Short of a freon refill, there isn't much you can't tackle with common sense, google, and a multimeter.

 

If you have access to a guage set, even a freon fill isn't tough. Just don't go in with the "more is better" mindset.

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