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Tim H.
Tim H., HVAC Professional
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Amcoraire minisplit A/C Model #AOS121HX Not cooling/heating P4

Customer Question

Amcoraire minisplit A/C
Model #AOS121HX
Not cooling/heating
P4 and p8 error codes

After having the A/C head unit previously installed. I had to remodel and relocate the head unit to another location in the room. Not being an A/C Tech myself, i needed to move it out of the way for the remodel crew and could not wait for an A/C tech to do it due to scheduling conflicts. So I unscrewed both the 1/4 " and 3/8" (gas and liquid) lines from the compressor. It vented all the gas. I dont remeber how soon after, but i did tape the open ends of the copper lines to prevent dust and moisture. (my back yard is not landscaped and has alot of loose soil that could find its way inside the lines). I then disconntected the lines from the head unit and removed the head unit from the wall to relocate a a later time. i taped that end of the lines and left them in the attic until the remodel was complete.

A few weeks later I reassemble the lines to the unit in the new location. To save some cash, I recruit my brother who went to a/c tech school and has some knowledge and tools to vacuum and recharge my system. (He is by no means a licensed tech, nor has ever worked on a mini-split system before) He ran a vacuum for at least 1 hour before adding the proper amount of refrigerant. This unit calls for just over 3 pounds of refrigerant. The only thing that he did not know is if it called for to be put in as a gas, or as a liquid. So, when recharging the a/c in a gas state was taking to long,(impatient guy) he turns the tank upside down and completes the charge in liquid form to within 1 oz under the spec called for. The unit worked, but It never was super cold like it was when it originally installed. I used it through the winter as a heat pump for a few months but it never heated the room properly. I then started getting a P8 code and a P4 code after restarting the unit.

I get my brother back to trouble shoot it. It turns out that all the refrigerant has slowly leaked out over a 3 month period. It has no charge at all. We determined that the 3/8" gas line may have been damaged when I relocated the unit. So I cut the white insulation from the entire length of both the copper lines. I found many DEEP KINKS throughout the 3/8" line which could previously could not be detected with the insulation wrapped around them. I then went to my local Lowes and bought a 20Ft coil of copper tubing. (they only come in 20ft and then jump to 50 ft.) So I cut 5ft of copper from a non kinked length of the original line and soldered them together with a coupling to get the required 25ft. I ran the new line and flared the ends and reattached the new non-kinked line and left the 1/4" line alone, as I did not see any kinks on it. My Brother then recharged the unit in the same manner as before. ( both gas and liquid).

IT ran great for about a week. When I went into the attic to wrap the line with insulation when I noticed that the 1/4" line was covered with frost. It looked like it was frozen over. My brother could not explain it. After a few more days as running the A/C I notice that that the air coming out was not as could as before. Then, the head unit gave me a P4 code.
That brings me up to the present. I know that this post is quite long, but I wanted to give the complete history of this unit so that I can get the most accurate answer to fix my unit. Thank you in advance for any answers that can help me out.
Submitted: 6 years ago.
Category: HVAC
Expert:  Tim H. replied 6 years ago.
Thanks for giving me the opportunity to help! These units are usually weighed in charge and charge must be very exact. It also sounds like you have problems with leaks throughout the system. It is very hard to form refrigeration flares that will not leak. You need to be somewhat a pro with flaring to get them to hold pressure. Usually once I have the whole system put together and BEFORE I pull a vacuum or recharge, I fill with nitrogen and let stand for 1/2 hour or so to verify that no leaks exist. It's also important to use a micron guage when pulling a vacuum to make sure that all non-condensables are removed.
It might be time to call in a professional as you can damage this system if it is run with air and non condensables in the system.
Customer: replied 6 years ago.

I understand that this system is very tempramental. It needs exact specs or it will not run correctly. However. Other than your comment on the Flare connections, your answer to my very long and detailed post is extremely vague. I agree that there may a problem with leaks. My brother will borrow a nitorgen tank and a newer micron gage when we try to recharge the system for a third time. We will first eliminate the flared compression fittings and instaed permanently sweat both the copper lines to both the head unit and to the copressor sides to rule out any possiblitiy of leaking from those points in the sytem. i do have a question though. CAN HE USE CO2 INSTEAD OF NITROGEN WHEN DOING A LEAK TEST? also DOES THE CHARGE OF THE R410A REFRIGERANT HAVE TO BE DONE IN THE GAS FORM (TANK UPRIGHT) OR THE LIQUID FORM (TANK UPSIDESOWN) OR DOES IT MATTER AT ALL? finally--- THE P4 CODE SHOWN BY THE A/C HEAD UNIT.... IF ALL THE ABOVE IS DONE AND I STILL GET THIS CODE, THEN WHAT DOES IT MEAN IS GOING ON WITH THE UNIT AT THAT POINT?
Expert:  Tim H. replied 6 years ago.
No, I've never heard of CO2 being used to pressurize a unit. For one thing it's going to be more expensive. Usually best to use nitrogen as it's dry and won't introduce moisture to the system. R410A has to be introduced as a liquid as it's a blend and can tend to separate as a gas.
As far as the P4 code, I'll check on that further but it sounds like you have a fair amount to do to get it running again.
After leak checking, I would try and pull it down to a minimum of 500 microns on the micron guage. 250 microns would be better, but not always achievable. Below 500 would be best.
Customer: replied 6 years ago.
Thanks for your input on the correct refrigerant input and vacuum measurments to look out for. It will prove very helpfull to my brother and I when we tackle this system again. But before I let you off the hook, I would realy like to know more info on the trouble codes that may arise should this next recharge may or may not encounter. Thanks.
Expert:  Tim H. replied 6 years ago.
I'll have to check on this and get back to you. Or, if you prefer, you can work with another expert.
Customer: replied 6 years ago.
Relist: Answer quality.
I need a detailed answer so that I can continue to service this air conditioning unit with the help of my brother who has a/c tech knowledge, but has no experience with the mini spit systems. I need exact information on my specific unit and model in particular. I also need a more than one question answered as technically as possible so that I can share the information with my brother.
Customer: replied 6 years ago.

Customer: replied 6 years ago.
still waiting.
Customer: replied 6 years ago.
Relist: Incomplete answer.
Please Have another Qualified expert that has experience with mini split a/c units review my previous post. Or please open it up to all the experts to give me their opinions on this question.
Customer: replied 6 years ago.
need to know what the trouble codes p8 and P4 mean when they appear on my head unit?

Thanks for your input on the correct refrigerant input and vacuum measurments to look out for. It will prove very helpfull to my brother and I when we tackle this system again. But before I let you off the hook, I would realy like to know more info on the trouble codes that may arise should this next recharge may or may not encounter. Thanks.
Expert:  Tim H. replied 6 years ago.
I haven't been able to get through to Amcor, but here is a manual for this unit with Amcor's contact information on the last page. Many of these companies have a technical support line and they may be able to help.