Mini split issues already?

So I went to check on room this morning it's been averaging 74-75 degrees since I'm at the end if the run. I just installed a mr cool mini split like 3 weeks ago. I've noticed these last two days the temps have been hitting 78-79 on 100%. Where as before I could hit that on 115%.

These past few nights it has been colder outside, down to lower 50's. This morning while the issue has been going on it's 63.

Does outside temps that low effect the ac or am losing 410 gas already? There was no freezing anywhere I could find. And the unit is supposed to alarm if low on gas but now I'm kinda paranoid that I already have a leak.

Let's just say I'm getting kinda frustrated with mini splits this is the second one I've had leaking if it is and I paid professional installation for the last one so did diy this one thinking I'd take the care to get it right.

Outside temperature will have an effect on the units maximum cooling capacity. If the unit is just barely big enough then it might do well when it's cool outside and not do so well when it's warmer outside.

If you have a leak there will usually be compressor oil present where the leak occurs. If it's a new install it may be difficult to see though.

Renfro said:

Outside temperature will have an effect on the units maximum cooling capacity. If the unit is just barely big enough then it might do well when it's cool outside and not do so well when it's warmer outside.

If you have a leak there will usually be compressor oil present where the leak occurs. If it's a new install it may be difficult to see though.

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I am suspecting a leak or maybe I'm just paranoid but I can't see why it's not keeping up as well if it's not leaking. Outside temps are actually cooler than they have been at night the last couple nights and that's when this has happened so if units work better when it's colder then I don't think that's my issue. My old unit leaked oil so I know what you mean and I've been looking but yet to find any might go cut the wrap off the line at inside connection and see if I can find any.

I still have another room to do and this has me leaning towards a traditional air handler with brazed lines. Last time I bought a Daikin and paid a couple different guys to fix it and it was never fixed. So needless to say I'm getting frustrated. I don't want to be fixing shit or having constant issues I just wanna grow some herb.

Well if it was my unit the first thing I would do is pump it down and weigh out the charge. That way I can see if there was a full charge in the system. If there was a low charge then I would connect a nitrogen cylinder and pressure test the unit (the evaporator coil usually has a max PSI rating and thats our target) so say thats 400 PSI, we pressurize the system with nitrogen to 400 PSI and then using bubble test we inspect all the connections for leaks. Often you can hear a leak with that much PSI. Find the leak and address that, then release the nitrogen and pull a hard vacuum on the system, then using a liquid low side charging adapter weigh in the proper charge. Now the unit should operate as intended.

Renfro said:

Well if it was my unit the first thing I would do is pump it down and weigh out the charge. That way I can see if there was a full charge in the system. If there was a low charge then I would connect a nitrogen cylinder and pressure test the unit (the evaporator coil usually has a max PSI rating and thats our target) so say thats 400 PSI, we pressurize the system with nitrogen to 400 PSI and then using bubble test we inspect all the connections for leaks. Often you can hear a leak with that much PSI. Find the leak and address that, then release the nitrogen and pull a hard vacuum on the system, then using a liquid low side charging adapter weigh in the proper charge. Now the unit should operate as intended.

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I'll have to pay a tech to do all that don't have the tools that's why I went diy. Smh, I have the worst luck with these units. My budget is about done for. I'll have to wait a couple weeks before can afford it. But I'll call around and see what it would cost maybe it won't be as much as I thought. Finding a tech that's wants to work on a diy unit might be a pain in the ass since it's not regular flare fittings they are used too.

do you have a thermometer to measure the air temp before and after the indoor unit ? by calculating the delta T you will know if refrigerant is missing
the big copper of the outdoor unit ( compressor aspiration) will freeze if you have a lack of r410. is that the case ?

Generally we want a delta T between 16 and 22 degrees. If it's lower than 16 you could indeed be low on charge.

Measure the temperature coming out of the unit and subtract that from the temperature going into the unit (return air) to get your delta T.

Make sure the unit is on max cool when you do this. Some units have a "Fast Cool" or "Turbo Cool" setting, this is what you want for this test.

what i noticed at-least from all the hvac work I've seen a lot of leaks come from 90/45 degree angles where the line set is bent. could be many things fwiw. imo i would try to see whats causing it if its a hole in a line-set it can be fixed you just gotta know what your doing if its too big of a hole good luck. end of the story have someone that knows what their doing do it. could be a couple things wrong

Apalchen said:

I am suspecting a leak or maybe I'm just paranoid but I can't see why it's not keeping up as well if it's not leaking. Outside temps are actually cooler than they have been at night the last couple nights and that's when this has happened so if units work better when it's colder then I don't think that's my issue. My old unit leaked oil so I know what you mean and I've been looking but yet to find any might go cut the wrap off the line at inside connection and see if I can find any.

I still have another room to do and this has me leaning towards a traditional air handler with brazed lines. Last time I bought a Daikin and paid a couple different guys to fix it and it was never fixed. So needless to say I'm getting frustrated. I don't want to be fixing shit or having constant issues I just wanna grow some herb.

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FWIW did you try calling Mr. Cool support line? Since it's a new unit and they are designed for customer installation perhaps they have some things for you to check. I would get a delta T number first. I would think that it would be under warranty and I am not sure how they handle that.

There is no freezing anywhere that I've found yet, when trying to find the delta t is a laser thermometer good?

Apalchen said:

There is no freezing anywhere that I've found yet, when trying to find the delta t is a laser thermometer good?

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yes thats what you need
put the AC at full power in cold mode with fan full speed to take measurements

Apalchen said:

There is no freezing anywhere that I've found yet, when trying to find the delta t is a laser thermometer good?

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Yeah, just measure the temperature of the intake vent and the cold air vent.

I keep checking and haven't had a t delta of less than 18 the majority of time it has been 20. Although my laser thermometer seems to be not so accurate I just take a bunch of measurements and use the average one.

3 weeks? is it possible you have a clogged air filter?

you can also measure the intensity absorbed by the outdoor unit .. with a AMP plier
lack of gas will induce weak high pressure leading to a low intensity absorbed by the compressor

Herb & Suds said:

3 weeks? is it possible you have a clogged air filter?

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The inside unit is clean, it is possible with as dusty as it's been here that the outside unit is a bit dusty. I'll spray it off when get home. It seems temps want to climb early morning after running all night but so far only a few degrees, I guess it could be that by the end if lights on the concrete and everything else has heated up more.

BIGBALLSJOE said:

you can also measure the intensity absorbed by the outdoor unit .. with a AMP plier
lack of gas will induce weak high pressure leading to a low intensity absorbed by the compressor

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Can please explain how would do that?

Apalchen said:

The inside unit is clean, it is possible with as dusty as it's been here that the outside unit is a bit dusty. I'll spray it off when get home. It seems temps want to climb early morning after running all night but so far only a few degrees, I guess it could be that by the end if lights on the concrete and everything else has heated up more.


Can please explain how would do that?

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use a amp clamp to measure the intensity absorbed by the motor (ampere). put the clamp around the L wire

then read the nameplate on the ac outdoor unit.

compare the amp measured with the clamp on the ac at full power with the numbers written on the nameplate
if the numbers are way lower on your clamp meter.. you possibly have a lack of refrigerant

lack of gas =>weak high pressure=> decrease of current intensity

The first thing you should have done is download the app and see the current temp of the room and compare it to your environmental controller or whatever. I have the same mini split and Ive noticed that there is usually a temp reading difference between the system and my pulse. Just compensate for that difference and you should be fine if thats the problem.

Skylander said:

The first thing you should have done is download the app and see the current temp of the room and compare it to your environmental controller or whatever. I have the same mini split and Ive noticed that there is usually a temp reading difference between the system and my pulse. Just compensate for that difference and you should be fine if thats the problem.

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I need a WiFi extender with antenna, my building is metal with roughly 5 inches of insulation no signal at all out there. But I have the the unit set to lowest temp it will go at the moment. It's holding around 74-75 first few hours lights are on. By the time I wake up in morning it's about 77-78. I might just not have enough power, not that temps are too high per say, but I'd like more control to lower temps at the end. How many watts you cooling with yours?

Apalchen said:

I need a WiFi extender with antenna, my building is metal with roughly 5 inches of insulation no signal at all out there. But I have the the unit set to lowest temp it will go at the moment. It's holding around 74-75 first few hours lights are on. By the time I wake up in morning it's about 77-78. I might just not have enough power, not that temps are too high per say, but I'd like more control to lower temps at the end. How many watts you cooling with yours?

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if you use co2 78f is better than 75