# My Mini Split is in defrost mode this morning.



## Janderso (Nov 29, 2020)

I have a one ton Mr. Cool mini split.
It’s in the 20’s outside this morning.
The manual just says, defrost mode.
Anyone else seen this?


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## Boswell (Nov 29, 2020)

I don't know about a mini-split specifically buy the outside coils on my heat pumps for my house can freeze up when the conditions are right. well below freezing and high humidity. I know they have a Defrost mode that will prevent this most of the time. I assume it heats the outside coils.


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## Janderso (Nov 29, 2020)

Interesting. It makes sense.
 When I walked out in the shop this morning and saw, what I thought was an error code, nooooooo.


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## RJSakowski (Nov 29, 2020)

I haven't seen it with my Mr. Cool installation but I don't run mine in heat pump mode unless the temperature is above freezing.


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## Janderso (Nov 29, 2020)

RJSakowski said:


> I haven't seen it with my Mr. Cool installation but I don't run mine in heat pump mode unless the temperature is above freezing.


I have it on heat. I don’t know what that means mechanically though.


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## Tozguy (Nov 29, 2020)

In heat mode the system is chilling the outside coil and heating the inside coil. It is normal for the outside coil to frost up especially in the late fall when temps drop and relative humidity is high.

My heat pump regularly goes on a defrost cycle to remove the frost that builds up and impedes air flow through the outside coil. It does not have to be below freezing outdoors for this to happen. The defrost mode reverses the system so it is temporarily heating the outside coil and cooling the inside one. The outside fan stops during this cycle and the outside coil will drip water. An auxiliary heat source (electric element or fuel burner) is often applied inside so that no cooling is felt indoors. The system senses when a defrost cycle is necessary and kicks it in automatically. The defrost cycle on mine lasts around 3 minutes or less.


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## RJSakowski (Nov 29, 2020)

Janderso said:


> I have it on heat. I don’t know what that means mechanically though.


A heat pump is a refrigerator running in reverse.  The compressor does work moving heat from a colder point to a warmer point adding its work as heat.  As a result, you actually get more energy out than you put in. So more than 100% efficiency.  However the efficiency drops rapidly with an increasing difference between input and output temperature which is why basic heat pumps aren't used in colder climates.  Drawing the heat from the ground either with a large reservoir or a deep well can make cold weather heat pumps viable but that is definitely not the case with the mini split.

Add to the mix, there is an additional burden with thermal conductivity  bringing heat into the outside unit,now operating as an evaporator so you can get a freeze ip even though the outside temperature is above freezing.  This is why they add the defrost cycle.


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## Janderso (Nov 30, 2020)

How did you guys get so smart?
Very interesting.


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## pdentrem (Nov 30, 2020)

We found that our 1.5 ton MRCOOL would become inefficient right about 20F. We only use it from above that, otherwise works great.
Pierre


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## Tozguy (Nov 30, 2020)

My 3 ton York is the same. It does not heat well when outside temps are below freezing. It also makes more noise when straining near its maximum capacity. We simply turn it off and turn on the oil furnace.


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## Papa Charlie (Nov 30, 2020)

Interesting, I was not aware of the limitations of heat pumps.


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## alloy (Nov 30, 2020)

You guy are lucky, my MR Cool unit died.  

Fried a wire on a circuit board.  Waiting to hear back from them to see if they are going to warranty it.


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## Janderso (Nov 30, 2020)

alloy said:


> Fried a wire on a circuit board. Waiting to hear back from them to see if they are going to warranty it.


Sorry to hear about it. let us know what Mr. Cool does for you.
When I was pricing Mini-Splits I think I was drawn to Mr. Cool because of the DIY, the presence on the web and the tutorials.
They had good reviews also. There were other units that were a lot more money.
I hope these things last a decade and more.
Had I known they struggle at freezing temperatures I may have gone another route.
Living in Northern California in the valley is not like living in the mid west however.
We don't get too many days below 32.


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## alloy (Nov 30, 2020)

I just got this from Ingrams.

I'm not impressed easily, but this impresses me.  I called last Wednesday and got this shipping notice today.

No payment required.

I need to figure out if I need to have the system vacuumed down to install it, or can I just pull this lines and hook them to the new unit.  

And I'll need help moving the unit into place. Can't do that stuff anymore by myself.




*Hello, Dan Conley*
Thank you for your order from Ingrams Water & Air. Once your order has been successfully processed we will send you an email with an invoice for your records. You can check the status of your order at anytime by logging into your account.

Your order confirmation is below.*Order #100080074 (placed on November 30, 2020 3:34:28 PM CST)*
*Billing Information:*​*Payment Method:*Dan Conley

Silverlake, WA
United States
T:*No Additional Payment Required*


*Shipping Information:*​*Shipping Method:*Dan Conley

Silverlake, WA
United States
T:Shipping - Standard Freight


*Item**SKU**Qty*​*Subtotal*​*36k BTU 16 SEER MrCool DIY Ductless Heat Pump Condenser - 3rd Generation*HA208631​$1,386.47​Subtotal​$1,386.47​Shipping & Handling​$0.00​Discount (WARRANTY - NO CHARGE, WARRANTY - FREE SHIPPING)​-$1,386.47​Tax​$0.00​*Grand Total*​*$0.00*​

**** SHIPPING DAMAGE OR MISSING ITEMS ****​Unpack and inspect ALL packages for damaged or missing items before accepting the shipment!! If any damage is found, note this on the delivery receipt!! Although Ingram's Water & Air Equipment is NOT responsible for shipping damage, we can assist with filing a claim against your freight carrier to cover the cost of the damages. The damages or missing items have to be noted on the delivery receipt prior to signing for and accepting the shipment, in order to file a claim. Do not let the delivery driver rush you. It is your right to inspect each and every item. He WILL wait until you're finished.
************************************************************​If you have any questions about your order please contact our customer service team at support@iwae.com or call us at 1-270-575-9595 during our business hours:


Mon - Fri:7:00am - 7:00pm (CST)Sat:9:00am - 3:00pm (CST)Sun:Closed


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## Janderso (Nov 30, 2020)

Holy Cow, I paid that much for my 12K Mr. Cool.


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## pdentrem (Nov 30, 2020)

Unless one is using a geothermal heat pump, supplemental heat is required. Some split units have electric heater built in while whole house units are attached to a furnace.
Pierre


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## RJSakowski (Nov 30, 2020)

I have an 18 kBtu Mr. Cool in my 300 sq. ft. attic workroom space.  I also have four 1 Kw baseboard heater.  Although the space is insulated from the remainder house, the chimney from the wood burning furnace runs through the middle of the room and in coldest wether will keep the room at 55-60ºF.  I only turn on the baseboard heat if I am working up there and the Mr. Cool in heat pump mode if it is above freezing.  Mr. Cool states in their operation manual that heat pump performance may be poor if operated below 45ºF outside temperature.

AFAIK, only the DIY series comes with precharged lines compressor.  All other will require a pump-down with a vacuum pump and system charging.  One should also note that if the system requires pump-down and charging that some municipalities require installation be done by a certified HVAC person.  Although I have the equipment and knowledge to install such a system, I chose the DIY version because my compressor is not at gtound level and I chose not to have to mess around with making relatively more complicated connections, pump-down, and charging.


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