Dismantling a mini-split?

[MushCreek]

I'm going to attempt to repair my leaking Mitsubishi mini-split. The leak is in the interior heat exchanger coil. I can get a new one for less than $200, and I'll have my A/C guy evacuate and re-charge it when I'm done. I have a service manual, but I'm not sure how to shut off the refrigerant lines. There's a gas valve and a liquid valve. I assume I shut them off first. Then I should be able to disconnect the lines at the coil, although some freon will leak out. The manual calls for 'pumping it down' first, but I don't have the equipment or know-how, and don't want to pay for the A/C guy to come out. Since it's been leaking, and hasn't been run in a couple weeks, I'm assuming that there won't be that much pressure or freon left in the lines.

Am I looking at this right? Any pointers? I guess the small amount of freon won't hurt anything, as it's been leaking anyhow.

 

[Git]

I am not an 'expert' but I do have a Mr Slim. The manual indicates how to pump it down - all you need is a gauge set. Check your manual, this is from mine

 

[MushCreek]

'Connect the gauge manifold'. I don't have any A/C tools. What you're doing is pumping the freon into a tank. I'm not gonna go out and buy all of that for a one-shot deal.

 

[bonneyman]

I'm going to attempt to repair my leaking Mitsubishi mini-split. The leak is in the interior heat exchanger coil. I can get a new one for less than $200, and I'll have my A/C guy evacuate and re-charge it when I'm done. I have a service manual, but I'm not sure how to shut off the refrigerant lines. There's a gas valve and a liquid valve. I assume I shut them off first. Then I should be able to disconnect the lines at the coil, although some freon will leak out. The manual calls for 'pumping it down' first, but I don't have the equipment or know-how, and don't want to pay for the A/C guy to come out. Since it's been leaking, and hasn't been run in a couple weeks, I'm assuming that there won't be that much pressure or freon left in the lines.

Am I looking at this right? Any pointers? I guess the small amount of freon won't hurt anything, as it's been leaking anyhow.

It's a real Catch-22. I feel for your plight, but you're asking for trouble messing with the sealed system on your own. Especially if the system is R410a.
You can't wing it - you're liable to wreck the unit or have to have some AC guy come out and fix your repair attempt. Would hate to see that happen.

 

[MattT]

'Connect the gauge manifold'. I don't have any A/C tools. What you're doing is pumping the freon into a tank. I'm not gonna go out and buy all of that for a one-shot deal.

No what you generally do is close the high side service valve and run the unit in high/emergency cool until it recovers all the refrigerant into the outdoor unit and pulls the low side down to atmospheric pressure. Then close the low side service valve. That's the basic procedure but read the service manual for your mini before you attempt it.

And you're not looking at a ton of money to do this right.

https://www.pioneerminisplit.com/pr...ng-service-gauge-hose-set?variant=33782648720

 

[jhelrey]

The tools or repair tech is cheaper than the possible $37,500 in fines you could face for releasing refrigerant into the atmosphere.

 

[Ohmthis]

The tools or repair tech is cheaper than the possible $37,500 in fines you could face for releasing refrigerant into the atmosphere.

Or worse, the damage that the high pressure refrigerant will do to your body. I’ve personally had burns on my hands from a short blast of liquid refrigerant. That in your eyes or other sensitive areas will hurt and the potential of permanent damage SHOULD be enough to stop you from doing that. Please use your brain and think this out safely!!!

 

[MushCreek]

OK- I guess I'll have the guy come out and pump it down. He didn't really want to remove the coil, but rather replace the entire indoor unit (about $700, plus labor). I figure I have nothing to lose by attempting to remove just the coil. If I screw it up, I'll just get the whole unit. I won't order the coil until I see what's involved in replacing it.

 

[PoorOwner]

it looks like a pain in the rear end

 

[bonneyman]

They really don't make mini-splits to be "repairable". Overall size, desired SEER ratings, and production costs are all geared toward getting the most profit out of the least material. Plus, most "service" companies now really don't want to do service - they want the big bucks of installs. So they lean on their employees to push replacement over repair for anything bigger than a stuck relay. Just look at the pricing structure of most "service" calls. They're geared toward making the repair cost high enough where most customers will just opt for a new unit. Manufacturers sells more, companies make more, and employees are paid a commission from every unit they sell, so they make more. And the customer pays! I'm disgusted with how the industry has gone the last 20 years but I'm only one company.

 

[MushCreek]

Yes, it looks like a pain, but they no longer make my head unit. I can get a similar one, but they don't want to warranty it since its no longer a matched system. I might just order a head unit anyway and take my chances. I'll let the pro install it.

 

[MushCreek]

Just a follow-up- I had a local guy pump it down. I then replaced the coil, buttoned it all up, and had the guy put in the proper weighed charge. It's been running perfectly ever since. Taking it apart was a PITA, and putting it back together was no better. There isn't one spare millimeter of space inside of those things. Hopefully, it lasts for a few more years, and then I'll replace the whole thing. The coil was heavily corroded; it looked like it had been in a salt water environment. The refrigeration lines are corroded, too. I can't figure out what's causing all of the corrosion, as we're hubdreds of miles from the coast.

 

[Jackfre]

Ask your contractor if he can help you get a bit deeper into Mitsu's web site on the tech end. They may well have a video on disassembly of the evaporator. How much is a new evap? Is your covered by warranty?

 

[MushCreek]

The problem is that they no longer make my indoor unit. I can get parts for it, but not the whole thing. If you mix the indoor and outdoor units, they won't warranty it at all.

 

[justinjoyal]

Just a follow-up- I had a local guy pump it down. I then replaced the coil, buttoned it all up, and had the guy put in the proper weighed charge. It's been running perfectly ever since. Taking it apart was a PITA, and putting it back together was no better. There isn't one spare millimeter of space inside of those things. Hopefully, it lasts for a few more years, and then I'll replace the whole thing. The coil was heavily corroded; it looked like it had been in a salt water environment. The refrigeration lines are corroded, too. I can't figure out what's causing all of the corrosion, as we're hubdreds of miles from the coast.

Is it an inverter system or the traditionnal on/off type ?

Do turn the unit off sometimes after running A/C or do you leave it on pretty much the whole time ?

 

[MushCreek]

It's an inverter system. It definitely works better to leave it running all the time (in season). In the summer, it only cost $20/month to run it 24/7, and that's in hot and humid SC. Very well insulated house, though. We go for 2-3 months in the spring and fall without using heat or A/C.

 

[PoorOwner]

No brazing needed?

 

[rlitman]

It's a real Catch-22. I feel for your plight, but you're asking for trouble messing with the sealed system on your own. Especially if the system is R410a.
You can't wing it - you're liable to wreck the unit or have to have some AC guy come out and fix your repair attempt. Would hate to see that happen.

+1. Either it's already empty (which has it's own issues), or you want to call someone to pump it down.

No what you generally do is close the high side service valve and run the unit in high/emergency cool until it recovers all the refrigerant into the outdoor unit and pulls the low side down to atmospheric pressure. Then close the low side service valve. That's the basic procedure but read the service manual for your mini before you attempt it.

And you're not looking at a ton of money to do this right.

https://www.pioneerminisplit.com/pr...ng-service-gauge-hose-set?variant=33782648720

If it weren't leaking I'd agree.

But now that you have a leak, by pumping it down like this, the leak will **** in air as the lines start to get under vacuum, and you'll cause all sorts of problems.

This is a situation where you should NOT follow the book to pump it down, but just call in a pro.

Just a follow-up- I had a local guy pump it down. I then replaced the coil, buttoned it all up, and had the guy put in the proper weighed charge. It's been running perfectly ever since. Taking it apart was a PITA, and putting it back together was no better. There isn't one spare millimeter of space inside of those things. Hopefully, it lasts for a few more years, and then I'll replace the whole thing. The coil was heavily corroded; it looked like it had been in a salt water environment. The refrigeration lines are corroded, too. I can't figure out what's causing all of the corrosion, as we're hubdreds of miles from the coast.

Corrosion could be caused by a lot of things. Is the copper in contact with another metal? Something dripping on it?

 

[MushCreek]

No brazing required to change out the coil. It has fittings for the refrigeration lines.

The corrosion is everywhere- in the house, outside, etc. Nothing dripping on the coil, that's for sure. Our house is built of concrete, but the unit is on an inside wall. No Chinese drywall, either.

 

[BD1]

+1. Either it's already empty (which has it's own issues), or you want to call someone to pump it down.



If it weren't leaking I'd agree.

But now that you have a leak, by pumping it down like this, the leak will **** in air as the lines start to get under vacuum, and you'll cause all sorts of problems.

This is a situation where you should NOT follow the book to pump it down, but just call in a pro.



Corrosion could be caused by a lot of things. Is the copper in contact with another metal? Something dripping on it?

Do you have well water ?? Sulfur attacks copper. I have sulfur water and it destroys refrigerators and my AC. Sulfur in the air does it. Hard to believe but true.


Sent from my iPhone using Tapatalk

 

[MushCreek]

No, we have city water from a mountain reservoir. AFAIK, no sulfur in the water. In FL, well water had a lot of sulfur.

 

[PoorOwner]

is your outdoor unit corroded too?

 

[MushCreek]

Somewhat, although I didn't go digging deep inside to see. The refrigerant lines are quite green, though.

 

[rlitman]

Somewhat, although I didn't go digging deep inside to see. The refrigerant lines are quite green, though.

That's not good. Do you perhaps have some electrical current leaking? A bad ground? Something has to be causing that severe corrosion.

 

[PoorOwner]

So the copper are green indicating there is something acidic in the air, like if you used flux to clean the pipe and left it.

Do you have any exposed copper water pipes to compare with?

 

[MushCreek]

No flux involved; no soldering. I have very little copper in the house, but I haven't noticed any corrosion on it. It's either cheap materials, or as said, maybe an electrical current causing a galvanic reaction. The system has an independent ground wire in the control circuit from the inside unit to the outside. I better check that for continuity, although I know the ends are in good shape, as I saw both ends of the wiring recently. No corrosion on the wiring, BTW.

 

[LS6 Tommy]

The problem is that they no longer make my indoor unit. I can get parts for it, but not the whole thing. If you mix the indoor and outdoor units, they won't warranty it at all.

If you're not a licensed installer, Mistsu will not honor the warranty at all.

Tommy