Mini split condenser icing up (just outside the defrost parameters)

[SALIV8]

Hey guys. Ive had this gree mini split unit for approx 2 years. Im wondering if it may be slightly low on charge. Maybe i have a slow leak somewhere? I saw ice build up on this 4 zone heat pump and watched it slowly get worse.

I was expecting the defrost cycle to kick in but it did not. So I checked the service manual.

The outdoor temps were just above the defrost parameter (of below 41*F) it was 42-43* F outside and the unit also needs to see 3 hours comp run time with a coil temp of below 31*.

The outdoor humidity was 73%. I know theyre supposed to frost up but thought this was too much ice so I shut the unit down.

What do you guys think? Im goin to contact my installer and see what he says. It was heating well for a few days prior to this issue.

 

[Tracs]

I have a 18k btu Perfect Aire and it ices up like that when the drain freezes up. Goes into defrost mode, melts all the frost off and freezes in the bottom of the pan. My unit does not have a pan heater.

 

[theoldwizard1]

The outdoor temps were just above the defrost parameter (of below 41*F) it was 42-43* F outside and the unit also needs to see 3 hours comp run time with a coil temp of below 31*.

The outdoor humidity was 73%. I know theyre supposed to frost up but thought this was too much ice so I shut the unit down.

Hopefully that defrost temp can be changed !

 

[SALIV8]

I have a 18k btu Perfect Aire and it ices up like that when the drain freezes up. Goes into defrost mode, melts all the frost off and freezes in the bottom of the pan. My unit does not have a pan heater.

Mine has a pan heater.

 

[SALIV8]

Hopefully that defrost temp can be changed !

Nope. Not adjustable.

 

[SALIV8]

It’s back in service so we shall see.

 

[yeldogt]

You may have been in that dead zone .... do you think it ran 3 hours?

I have never had that happen .. they do get frosty on those weird days

 

[SALIV8]

Hopefully it was just in that weird humidity/temp dead zone. It did run for 3 hours but the temps were steady just outside the defrost parameters.

 

[Kaizen]

Have you ever cleaned it and the head units? I had that problem when it was dirty.


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[SALIV8]

Yes i have cleaned the condenser last year. Its probably due. As soon as it warms up i will clean the system again. Thanks.

 

[floridafarmer]

Have you ever cleaned it and the head units? I had that problem when it was dirty.


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Kaizen - how did you clean the head unit? I have Daiken 24,000 btu unit and it's not as cold as is it used to be - I clean the black dusty film off the condenser a couple of times a year and it always seems to improve quickly but now it's still cool but not cold. Last year I tried to clean the head unit as best I could but not sure I did it right. Curious on how you did it.
Thanks

 

[theoldwizard1]

Icing on A/C units is typically a sign of low refrigerant.

 

[SALIV8]

This is a heat pump.

 

[Jackfre]

Kaizen - how did you clean the head unit? I have Daiken 24,000 btu unit and it's not as cold as is it used to be - I clean the black dusty film off the condenser a couple of times a year and it always seems to improve quickly but now it's still cool but not cold. Last year I tried to clean the head unit as best I could but not sure I did it right. Curious on how you did it.
Thanks

I love mini-splits and wouldn't be without them, but they are just a ***** to clean and you do have to keep up with them. I'm looking at two evaps that are going to get it soon. On the internal unit, remove the whole cover. Get some poly sheeting and tape it around the unit. Vacuum the face of the coil. Be very careful the fins are very light and the slightest touch will deform them. You will likely find the greatest accumulation of dirt on the back side of the coil. I use new Calgon coil cleaner in a pump sprayer and them wash the hell out of it. The heavy poly sheeting I gang into a plastic tub or garbage can...that I know holds water. Once you are satisfied on the coil you have to get at the blower wheel. Some remove the blower section and make this much easier. I'm dumber than a post so I do it in place and ***** a lot. The curved blades load up and are difficult to get at, but it can be done. Again, use a pump sprayer or whatever you can come up with. I'm going to try out a new method I've dreamed up. Garden hose t the unit. One that doesn't leak. 15 or 25# plastic irrigation pressure reducer X 1/4" non-perf drip tube. I haven't figured out the valve yet but put something in there. That is small enough and flexible enough and pressure will be consistent. Did I say these are a ***** to clean. Oh, you won't believe how well they work afterward.

 

[floridafarmer]

I love mini-splits and wouldn't be without them, but they are just a ***** to clean and you do have to keep up with them. I'm looking at two evaps that are going to get it soon. On the internal unit, remove the whole cover. Get some poly sheeting and tape it around the unit. Vacuum the face of the coil. Be very careful the fins are very light and the slightest touch will deform them. You will likely find the greatest accumulation of dirt on the back side of the coil. I use new Calgon coil cleaner in a pump sprayer and them wash the hell out of it. The heavy poly sheeting I gang into a plastic tub or garbage can...that I know holds water. Once you are satisfied on the coil you have to get at the blower wheel. Some remove the blower section and make this much easier. I'm dumber than a post so I do it in place and ***** a lot. The curved blades load up and are difficult to get at, but it can be done. Again, use a pump sprayer or whatever you can come up with. I'm going to try out a new method I've dreamed up. Garden hose t the unit. One that doesn't leak. 15 or 25# plastic irrigation pressure reducer X 1/4" non-perf drip tube. I haven't figured out the valve yet but put something in there. That is small enough and flexible enough and pressure will be consistent. Did I say these are a ***** to clean. Oh, you won't believe how well they work afterward.

Thanks - I made a little bit of a mess - back side of the coil had the most dirt and the blower wheel was much happier after a wash down. Unit is running better now for sure - thanks for the reply.