Mr Cool indoor unit freezing up

[Fueler]

Installed 2 years ago and everything has been fine.
We finally had a nice few days so the wife shut it down and opened up the house to air out. Those nice days went away late yesterday and she turned it back on. Today was miserable humidity and she complained it wasn't working right. Sure enough the air stream was pretty lame.

I have been cleaning the filters the first of the month. Since we were closing in on a month I figured the cats had been overshedding and it was time for another cleanout.
Imagine my surprise when lifting the lid to find it all frozen up.

What am I looking at here?
What is the next step after I get it thawed out and see if it works correctly again?
Thanks

 

[chrispyny]

Get it pumped down, then closed off, then pressurize with nitrogen and see if u can find the leak. Fix leak, then add appropriate amount of refridgerant.

Or call an hvac guy, he can do it for you, at a cost.

 

[aunsafe2015]

Get it pumped down, then closed off, then pressurize with nitrogen and see if u can find the leak. Fix leak, then add appropriate amount of refridgerant.

Or call an hvac guy, he can do it for you, at a cost.

Out of curiosity, why does frozen evaporator indicate leak?

 

[TRWham]

Low suction pressure resulting from low charge leads to low evaporator temp which in turn leads to iced evap.

 

[Bills Tools]

What about An intermittently operating blower motor? Why would anyone pump down the system for a leak search. Use the gas inside for a bubble test if you can’t find it then you can isolate the indoor cassette, the Condensor and lineset. Pressurize each piece with 450 psi and give it 2 weeks. When you come back wherever your leak is the pressure will drop then have that component repaired or replaced.


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[justinjoyal]

What about An intermittently operating blower motor? Why would anyone pump down the system for a leak search. Use the gas inside for a bubble test if you can’t find it then you can isolate the indoor cassette, the Condensor and lineset. Pressurize each piece with 450 psi and give it 2 weeks. When you come back wherever your leak is the pressure will drop then have that component repaired or replaced.


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You can use a leak detector if there is enough refrigerant/pressure left in the system and it still leaks.

However, if that doesn't work, you have to go the nitrogen way.

My customers would not be very satisfied if I took 2 weeks to find their leak, btw.

 

[Rockhead261]

The #1 cause of a frozen evaporator is poor airflow.

Is the filter clean?
Is the evaporator coil clean?
Is the blower scroll clean?

Visible dirt on any of the above has an impact on airflow. Despite being an obsessive filter cleaner, I find it necessary to disassemble my Mr. Slim and clean the blower every 2-3 years.

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[Fueler]

Update
It took around a couple of hours to get it defrosted.
Used a heat gun to speed up the process a bit.
Air filter screens looked clean but gave them another cleaning.
Used some coil cleaner on everything.
Ran the fan on high for a couple of hours to dry things out.
Ran the self clean mode.
Hard to see but the blower appeared clean.
Verified the drain was clear.

It's still running like it is supposed to a couple of days later.
Keeping an eye on it hoping to catch if and when the icing starts up again.
Not sure what to think at this point but if I dodged a bullet I rejoice.

 

[yeldogt]

It's my understanding that when they freeze (head inside) it can be because of high humidity -- plus ... running them on high.

I was told that since the metering device is out at the external compressor -- that's the point of low charge freezing. The lines in and out to the heads are just to move the cold or hot refrigerant. The units are designed to be "on" and maintaining the humidity level -- when you turn them on in a very humid room they can freeze or spit water .... I have seen this many times while overseas .. especially in Africa.

 

[Fueler]

That in fact may have been the scenario.
On further interrogation the wife stood it as long as she could. She's thrifty, bless her heart. When she turned it on she selected Cool and turbo instead of our normal Auto setting.

 

[sgiss]

My Mr. Cool froze up after a year. The service tech at $130.00 added refrigerant. He did not do a leak check (quoted $850.00). I determined/guessed/prayed that is was the shrader valve, which I replaced ($40.00 for the tool to do so without losing refrigerant). One year later, froze up again- and low airflow. I was all ready to assume a leak of refrigerant - but looked and saw the blower wheel was covered in mold. I cleaned that and it is working like new for the last 4 weeks. Fingers crossed.....

 

[Bills Tools]

You can use a leak detector if there is enough refrigerant/pressure left in the system and it still leaks.



However, if that doesn't work, you have to go the nitrogen way.



My customers would not be very satisfied if I took 2 weeks to find their leak, btw.

You ever have a system your leak detector and bubbles couldn’t find? A cut and cap is the best way to find tiny leaks. Big leaks are easy to find. It’s why recharging the system on service call then returning when system isn’t needed to do a cut and cap. Yet from what I read about the me cool systems. They should just be thrown away and replaced with new from how cheap they are. Not worth paying for a service call when 1 hour at 225 just for time is a quarter cost of new system.


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[eddieK]

You can use a leak detector if there is enough refrigerant/pressure left in the system and it still leaks.

However, if that doesn't work, you have to go the nitrogen way.

My customers would not be very satisfied if I took 2 weeks to find their leak, btw.

Great answer!