Why Does The Evaporator Coil Freeze (And How to Diagnose It)

This was a very good video

Most of the time it's low on refrigerant ,sometime has a restriction , almost never because the coils are clogged

As always, his videos are the best.

Thanks from Bangladesh.

You sound intelligent and spout intelligence. Intelligent video. Thank you!

How would you go about check the charge on a package unit where would I hook up my temperature clamps to properly check sub cool and superheat some units are kind of unacceptable unless you remove the condenser fan motor and scenarios like that?

Over the last three years I’ve diagnosed at least 100 freezing coils, all of them being poor airflow and/or low refrigerant. Last week had one that stumped me, a mortex down flow in a mobile home that had perfect refrigerant pressure, lsat, vsat, subcool, airflow, delta t, etc. but was freezing up sporadically. Turned out it was a 3 ton coil on a 4 ton condenser.

New Subscriber , Hi Every One , 🇲🇦

You speaking too Fast !

Why are you doing this ?

Can someone help me understand what he means by “ the market you are in “ ? Thanks gang.

1.check air filter first(just like you do with your vehicles)
2.take pic of the evap coil in selfie mode with phone so u can see the bottom (dont drop the phone lol)
3.check blower speed
4.check zone board and the wiring to see how many dampers your dealing with in the home

5.turn off one of the thermostats and keep 1 running and go to attic to inspect dampers and ductwork

6.make sure your dampers are close and open based on which thermostat you turned off and left the other on.

7. Make sure you put your hand on the vents to see if its off on the zone you turned off..

8. Go get your pressure readings

Hi. Thanks for the video. We have a Magicpak unit in a closet in our condo. It's dripping water in the closet and down the outside brick when it's in AC mode. It's new. Filter is new. Installer says he needs to contact the manufacturer. Very frustrating after $7,500. Any experience with those magicpak combo units? Thanks.

I do know when its 90 out and humidity approaches 95%….It becomes much easier for the “A” coil to freeze up, if it does, turn on the heat!!! Takes very little time to THAW out the coil and dry it out, works!! And then let the compressor cool down as well.

Not only did I learn a lot, but I realized how much I still need to learn. 10/10 it hurts

Hahaha I can't do half of those when all I am given is a one hour max to diagnose a system. I hate companies that just push you to do as many services as possible while neglecting so many other things. Most of the times I stay more after coming to a conclusion if I have the time to spend. But yeah I don't feel like I am using all my knowledge just because of greedy corporate agenda.

Can a split unit freeze due to excess charge?

What about units running during low ambient conditions, with no head pressure control? That has caused many evaporator coils to freeze up.

Great video like always thank you for sharing your experience with all of us 👍🏻🍺

Why is my Mitsubishi split unit leaking water from the condenser when the heat is off it is brand new I install for units all together that’s the only one doing it thank you

Good commonsense information, thanks.

very dirty in a lot of cases my coils were completely restricted from dirt

Thanks for the information, very helpful, and it confirms that doing anything other than changing the filter is way beyond anything I can do myself.

If I may add one more thing here based on personal experience, check if air flow control board sends proper voltage to the indoor fan so that it runs at full speed. A Trane unit had bad control board where the fan was not running at full speed, hence low air flow. I followed the manufacturer’s troubleshooting guidelines to pinpoint what the problem was.

Can icing cause the blower speed to fluctuate a lot but mostly run at very low speed? This is a problem I’ve been having during a recent spell of hot weather. Usually turning the system from cool to off for a while fixes the problem and then it’ll work fine again for a day or two. If I leave the system off but the fan on, it seems to blow at the expected constant low speed.

on a variable speed compressor like the bosch (25%-110%) ids 1.0 ; should the system be put into force mode (100%) before you test the temperature difference? for me in regular mode when its about 50%-70% compressor running load the Temp Delta is about 5-6 degrees however if I put it in force mode its under 2degrees. Manufacturer says it must be in force mode in order to be able to charge. I am assuming the same holds true for the Liquid line temp difference across the direr? is that true?

The help blocks the door open during hot lunch period to cool kitchen. 2 pm freeze up.

I know the refrigeration cycle but I can't visualize why low refrigerant would cause the evaporator coils to freeze. Can someone please explain it to me? Thanks in advance.

My favorite channel

Correct answer. The system is under charged. Sheridan college.

Our new HVAC began freezing up initially because the floor level intake coated the filter with dust from our dogs in about a week. With the advent of monsoon season here in Flagstaff the dust settled somewhat but humidity rose. At over 7000 feet, airflow is already at a premium. Finally, the zone system includes a very long 8 inch duct to the guest room, which demands cooling but only a wisp of air makes it through. Next step: I am adding a duct fan controlled by the damper for that zone. Don't know if it will be the final step in the fix but it should relieve the current issue.

On the plus side, we are very familiar now with the symptoms of icing, and our first step in dealing with it is to kill the 240V to the compressor. The second step is to swap out the filter if it has been in there more than two days. (We are now using a pair of K&N filters so there is no hesitation to swap them.) Half an hour gets the air moving enough to complete the defrost, which takes about an hour altogether. It could be a lot worse.

Having every basement vent closed and a dirty filter on a 100 degree will also cause this.

Is 40 degree drop from my vent temp inside to 110 outside optimal at 76 inside vent

What about operating heat pump in a/c mode below 60 degrees?

Restriction in air flow

Many years ...

Too dense of an air filter? From my experience (I'm not a repair tech, just built super energy effecient homes) is too small of an air return duct! In my homes I filtered at the return grill and at the HVAC unit. Yes I have to oversize my return duct (which cost more to install) and I put multiple return ducts throughout the home! If there's ice beyond that, then it's a mechanical failure. Air flow is very important across the coil.

Thank You

Speaks too fast. No need for this.

I had an window unit A/C that use to freeze up tight in the front of the unit. I took it out of the window and bought a new unit.

I'm still using a refrigerator that runs off of Amonia

Thanks you're the best.

When it’s a Loose belt on my Ac

great content thanks

AC dirty or low refrigerant.

25 years ago I helped with ac tech in highschool and he'd always complain about people not changing filters or using a high Merv filter.

What stuck with me is he always said it's a filter not a purifier

The air does't weigh less in the mountains it is just less dense. Wrong quantification.

Two reasons the evaporator freezes. Low airflow, low on gas

Great video

I just changed my filter bout a month ago, still like new, but coil frozed up bout 3” inch….. 😔🤞🏼🤞🏼

Hi! My ac condensator is dripping water only the half bottom of it. Ac still working perfectly, the problem is that if I leave it running for a long time the condensator freezes up and builds up ice and then blocks the air from coming out of the vents... My ac is on a Condominium where cooling towers are used. What can I do to stop the leaking? Thanks in advance!