A-coils freezing GOODMAN aruf363616

[Wendell Brink]

So I have a Goodman ARUF363616 system that was installed horizontal and in my attic. When I would turn the unit on it would cool excellent and the air force could be heard. After about 30 minutes the a-coils would freeze thus the air force was reduced. Hvac person checked freon level and it was good. I cleaned the a-coils very well, the filter is brand new, I installed a new blower motor, new transformer, new computer board, and new capacitor. All ducts are open and cleaned, no blockage of any kind. .. I am so confused as to what the problem is. I understand the icing over restricts the air flow thus the airflow becomes restricted and noise is quieter. The company that installed this unit obviously didn't send out a tech. that wanted to troubleshoot the problem deeper. I really need some help

 

[Dana]

When the refrigerant charge is known to be proper, icing is a symptom of insufficient air flow, which could be from an inadequate duct design, or lousy implementation. Did it ever work properly?

The Goodman ARUF363616 is a 3- speed, but not sure about it's control scheme. If it can be hard-wired to run at only the intermediate or high speed it may fix the problem.

 

[Sponsor]

 

[Stuff]

Cooling excellent and hearing air force can both be flags of an oversized system and/or too small vents. How was the system sized and vents designed? A tech can confirm if there is an air flow problem by measuring the air pressure before and after the blower.
Also check that condensate is actually coming out of the system.

 

[Wendell Brink]

When the refrigerant charge is known to be proper, icing is a symptom of insufficient air flow, which could be from an inadequate duct design, or lousy implementation. Did it ever work properly?

It was working fine 2 years ago and just slowly started to do this. So I've attached some pictures of the control board. What wires would you suggest in changing the speed of the motor?



The Goodman ARUF363616 is a 3- speed, but not sure about it's control scheme. If it can be hard-wired to run at only the intermediate or high speed it may fix the problem.

 

[Wendell Brink]

https://drive.google.com/file/d/0B8GdjruNmro7QlIwUE4xVTItM2M/view?usp=drivesdk

 

[Wendell Brink]

https://drive.google.com/file/d/0B8GdjruNmro7QlIwUE4xVTItM2M/view?usp=drivesdk

https://drive.google.com/file/d/0B8GdjruNmro7ZWNzSGtyUmcwMWs/view?usp=drivesdk

 

[Wendell Brink]

Dana, I didn't know if my Google drive pictures were sent correctly?

 

[Wendell Brink]

Let's say the blower is currently on high speed. If I change the speed to medium or low I'm not understanding how that could possibly fix the problem. In my mind it would seem that moving less air would actually make it ice up quicker. Help me understand.

 

[Dana]

Let's say the blower is currently on high speed. If I change the speed to medium or low I'm not understanding how that could possibly fix the problem. In my mind it would seem that moving less air would actually make it ice up quicker. Help me understand.

If the blower is currently on high speed, slowing it down would make the problem worse, not better. If it's currently running at it's lowest speed bumping it up to intermediate or high would improve it.

If it was working fine for years and slowly evolved to it's current dysfunction, some possibilities are that there is slowly collapsing flex duct, or major crud accumulation in the ductwork restricting duct flow. (Are any large pets missing? )

The google drive pics work, but it's hard to read a low-res schematic on it's side. Take a hard look at Note 3, and see if you can't figure it out. The resolution of the picture isn't good enough to read the font with certainty, but it's also impossible to read the reference designator silkscreen in the photograph of the board obscured by the red wire in the lower left, or what other options there may be. A similar schematic in an online manual note 3 reads:

3) CONFIRM SPEED TAP SELECTED IS APPROPRIATE FOR APPLICATION. IF SPEED TAP NEEDS TO BE CHANGED, CONNECT APPROPRIATE MOTOR WIRE (RED FOR LOW, BLUE FOR MEDIUM,AND BLACK FOR HIGH SPEED) ON "COM" CONNECTION OF THE EBTDR INACTIVE MOTOR WIRES SHOULD BE CONNECTED TO "M1 OR M2" ON EBTDR.

Sounds like the black on the COM, with the red & blue on M1 &/or M2 it should be running at high speed, which seems to be how it's strapped in your picture.

 

[Stuff]

From the pic it is set up for high speed (high/black on common, low/red on holding/park terminal M1, medium/blue on M2).

Manual and wiring diagram - https://www.alpinehomeair.com/related/RT6121000R19 11.2012.pdf

 

[WorthFlorida]

Dana is correct that restricted air flow will cause any AC system to freeze but he also mentioned that the pressures must be correct.

If your system worked for a few years with no problems, you changed the filter, there are no other restrictions, the system is low on refrigerant. If there is a leak somewhere and it will be on the low pressure side and possibly the A-coil has a leak. A good AC tech will have a sniffer to check for leaks. Or After a few cold winters, parts shrink and may have leak a little each year and finally the pressure is too low. Doctors use stethoscopes to look for problems, AC techs use gauges, there is no other substitute.

Changing all the other components, unfortunately, has nothing to do with icing unless the blower was not working at all. A failed capacitor could also prevent the blower from running or rotate too slow. If a leak occurs on the high pressure side it would be empty of refrigerant in about 1 or two minutes, then a pressure switch would prevent the compressor from running.