New Split AC Unit; No Vacuum = leak?

[nexusroot]

Hello,

I bought a mini split AC unit for my garage and the install seemed to go smoothly. It's precharged with r410a for the 1200btu condenser, and about a 20ft lineset run. I went to do the initial evacuuation and i couldn't pull a vacuum below 0inhg. I had a cheap POS flaring tool and vacuum pump so I decided to buy quality tools and redo the flares and try evacuating again. However I'm still unable to pull a vacuum. There's 4 total flare nuts, and I've remade them all seperately about 5x each. Still cant pull a vacuum below 0. I used soap/water bottle and sprayed the flares, the charge hose and manifold, everything threaded. I don't see any water being pulled in, obv no bubbles. So I opened the valvestem to the gas for a fraction of a second and built up pressure to about 150psi. I then used soap and water over all the connectors and saw no bubbles. Freon gas detector also detected nothing. I disconnected my manifold from the packed valve port and let it sit for 2 days, didn't see a single drop in psi. Tried to draw vacuum again and I still can't get below 0!

It's rather frustrating. The only way I can figure that I can't get below 0 is because theres a leak, but you think it'd be so noticable that I would've found it with soap/water, a stethescope, or the freon detector. Also I would've figured since it wont go below 0 then it wouldve been a large enough leak to loose at least 1 psi over 48hrs when pressurized.

I know for the sake of my condenser this needs to be evacuuated to remove any o2/h2o that would interact with the r410a, but it's so frustrating I'm tempted to just open the valvestems and use it as is. I've been trying to find this leak and get this unit opperational for over a week now, meanwhile working in 95° temperatures.

I don't really know anyone around here who's an hvac tech that can help me out. I called a few local places, they either don't want to help because they didn't do the installation, or they want to charge 500$+. I'm hoping for some advice on how else I may be able to locate this.

Or maybe I'm just doing something horribly wrong, this is my first real stab at AC outside of a vehicle. I'm using the instructions provided with the unit http://www.senville.com/manuals/aura/aura-installation-manual.pdf . There's two valves on the outside, one with a tap for the manifold hose (the larger of the two pipes - I believe the gas line). I hook my manifold center hose on to there, open the valve on the left side of the manifold (manifold right valve is shut all the way). I have the left hose hooking into the top of my vacuum pump. Then I turn on the vacuum pump. Let the vacuum pump run for 30min (I let it go for a couple hours once and still got no further). Still wont go below 0inhg.

Thanks for your help.

 

[Mike007]

You need to get someone there who knows what they are doing. You can't leak check with refrigerant since the pressure changes with temperature. You never want to spray anything on a joint that's in a vacuum.

You need someone who knows what they are doing to leak check with nitrogen then do a proper evacuation. It will be cheaper then replacing the system in a year if there's a leak and you end up running it in a vacuum.

 

[nexusroot]

You need to get someone there who knows what they are doing. You can't leak check with refrigerant since the pressure changes with temperature. You never want to spray anything on a joint that's in a vacuum.

You need someone who knows what they are doing to leak check with nitrogen then do a proper evacuation. It will be cheaper then replacing the system in a year if there's a leak and you end up running it in a vacuum.

Thanks; I cannot pay someone 500$ to do that. It's simply not an option. I exhausted most of my funding buying this unit. And if I pull near -30inhg any water that may have been pulled in through a fitting would be pulled into the vacuum pump or evaporated at that pressure/heat.

 

[zmaxmotorsports]

Do you have the high and low side guages hooked up or does your your system have only 1 service port?
If you have 2 service ports open only the high side gauge and let it run to see if the needle on the low side gauge starts pulling a vacuam, then youll know if something is obstructing the system.
If you do have access to a nitrogen bottle and regulator its definately easier to leak check.

 

[nexusroot]

Do you have the high and low side guages hooked up or does your your system have only 1 service port?
If you have 2 service ports open only the high side gauge and let it run to see if the needle on the low side gauge starts pulling a vacuam, then youll know if something is obstructing the system.
If you do have access to a nitrogen bottle and regulator its definately easier to leak check.

The system only has 1 service port on the low side. I dont know anyone who would have a nitrogen tank but I can start looking around locally, not sure how much it's going to cost though.

 

[danski0224]

It's not a big deal because it is always cheaper to do it two or three times than correctly the first time...

How do you know that your gauges are working?

How do you know that your pump is working?

How do you know that your hoses (and/or hose gaskets) are good?

You work on automotive AC systems and do not own a nitrogen tank and regulator to do leak checks before dumping refrigerant into the system?

Do you have a micron gauge that actually tells you something about the vacuum or are you relying on an analog gauge at "-29.9" for 30 minutes?

Those mini split systems are critical charge. They hold ounces (not pounds) of refrigerant. When you dumped the charge to do the leak check, now you will be underchaged at startup. The only way to fix it is to recover the refrigerant and *weigh in* new.

 

[nexusroot]

It's not a big deal because it is alsways cheaper to do it two or three times than correctly the first time...

It is actually, when it comes to paying an hvac tech 100$ an hour, and they cannot even guarantee they'll find and be able to repair the leak in that time. And then you have a small leak that you notice a few months later and they'll charge you the same again and again. I've been through this before. Also I like to learn and gain experience on how to do things for myself generally.

How do you know that your gauges are working?

I don't, I don't have another set of r410a gauges. Although theyre newish, it's on my list of possibilites.

How do you know that your pump is working?

I tried two different ones.

How do you know that your hoses (and/or hose gaskets) are good?

I don't, I don't have another set of hoses. Although theyre newish, it's on my list of possibilites.

You work on automotive AC systems and do not own a nitrogen tank and regulator to do leak checks before dumping refrigerant into the system?

I have done basic recovering and charging. I've obviously never had a problem finding a leak in my limited experience, or I would've invested in something like a n2 tank.

Do you have a micron gauge that actually tells you something about the vacuum or are you relying on an analog gauge at "-29.9" for 30 minutes?

My analog pressure gauge never goes below "0", it never reaches the negatives. It is not a micron gauge.

 

[danski0224]

Leak checking is a crapshoot and finding it is nothing more than time and material. I never guarantee it either, especially if it is in a coil. It isn't any different from taking your car to a shop that charges $100 (or whatever) an hour and they don't guarantee it either.

In a running system, it gets recharged (unless the system is flat or the leak point is obvious) and UV dye put in, if the customer chooses to pay for it. Then they pay to come back and look for the leak, or buy their own UV light and look for it themselves.

"Leak Fix in a Can" is a guaranteed death sentence for residential equipment.

You can't "fix" a leak without breaking open the system, which is more time and material. On old residential systems (inexpensive compared to almost anything else), it really isn't worth it. Customers really hate dumping hundreds+ into a leak repair only to have a new one pop up in an old coil, therefore, I typically refuse leak chasing and repair jobs.

As far as the vacuum thing goes, you either have broken equipment (tools) or you are doing something wrong.

Combination analog 22/410 gauges have the scale all scrunched up, so those kinda ****.

And yes, finishing a homeowner install of HVAC equipment is always tricky because (1) you don't know how well it was installed and (2) the customer always wants some sort of warranty (for free) on work not performed by the HVAC person.

 

[nexusroot]

Leak checking is a crapshoot and finding it is nothing more than time and material. I never guarantee it either, especially if it is in a coil. It isn't any different from taking your car to a shop that charges $100 (or whatever) an hour and they don't guarantee it either.

In a running system, it gets recharged (unless the system is flat or the leak point is obvious) and UV dye put in, if the customer chooses to pay for it. Then they pay to look for the leak, or buy their own UV light and look for it themselves.

You can't "fix" a leak without breaking open the system, which is more time and material. On old residential systems (inexpensive compared to almost anything else), it really isn't worth it. Customers really hate dumping hundreds+ into a leak repair only to have a new one pop up in an old coil, therefore, I typically refuse leak chasing and repair jobs.

As far as the vacuum thing goes, you either have broken equipment (tools) or you are doing something wrong.

Combination analog 22/410 gauges have the scale all scrunched up, so those kinda ****.

And yes, finishing a homeowner install of HVAC equipment is always tricky because (1) you don't know how well it was installed and (2) the customer always wants some sort of warranty on work not performed by the HVAC person.

Yeah it is a crapshoot, I don't want a guarantee that nothing will go wrong again; I just don't want to be lied to about them actually finding and fixing the problem rather then covering it up and charging 5-10x the actual gas price to top off the unit at the exact same interval every 3-4 months.

And I don't know about the car shop anology - I've never taken any car to one.

It's a brand new unit, brand new everything, and the valves to the condensor are shut so I don't have to worry about the leak being in there. I've done my best to take off the cover on the inside evaporator unit and spray the brazed copper joints and use the freon detector around/in it without any success as well.

Yeah I read about doing it with the dye, I don't want to make this a running system though until I can properly evacuuate the lineset. I might pickup another manifold/hose set just to test and I think I'm going to contact some local gas suppliers Monday and see how much it'd cost to rent or buy a n2 tank, and go from there.

Oh and I wouldn't consider a stop leak can, much like I wouldn't in a car. It makes about as much since as when people throw eggs and pepper in their radiators to stop a leak.

Thanks for the response.

 

[joel63]

Thanks; I cannot pay someone 500$ to do that. It's simply not an option. I exhausted most of my funding buying this unit. And if I pull near -30inhg any water that may have been pulled in through a fitting would be pulled into the vacuum pump or evaporated at that pressure/heat.

To backtrack a little:

1. Make sure the valve depressors on the gauge lines are sticking out far enough
to depress the Schrader valves. Some times they don't stick out far enough to
depress the valve cores. So no access to system.

2. Make sure the manifold hose gaskets on both ends of your hose are in good shape.


3. Make sure your vacuum pump is working properly.
Hook your low side gauge directly to the pump see if your pump is pulling
down. Should pull down to 30"

 

[bazar01]

I can help you test your vacuum pump using your R410 manifold gauge.

Hook up the yellow hose of your manifold to the vacuum pump port.
Make sure the blue and red hoses are parked and tight.
Close the low and high side manifold valves.
Run the vacuum pump.
Open the low side manifold valve.
It should pull a vacuum.
Low side gauge should drop below zero and settle at -29 to30 inches if vacuum pump works.

 

[nexusroot]

I can help you test your vacuum pump using your R410 manifold gauge.

Hook up the yellow hose of your manifold to the vacuum pump port.
Make sure the blue and red hoses are parked and tight.
Close the low and high side manifold valves.
Run the vacuum pump.
Open the low side manifold valve.
It should pull a vacuum.
Low side gauge should drop below zero and settle at -29 to30 inches if vacuum pump works.

Wow, I'm embarassed I didn't think of that. Yeah I did that and it did not drop below 0. The gaskets looked decent inside the hoses, hooked the low hose onto the parking spot then tried it on the high end with the high valve shut off, neither time would it drop below 0.

I don't think its the pump because I tried it on two different pumps, one of them being a nice robinair 8 cfm pump, and they both had the same problem. I'm going to assume its either a leak in the hoses or maybe the gauge itself. I wish I could hook an air hose up to it somehow and pressure test it. Oh well.

Maybe that's what I get for going ebay and not yellowjacket with that one lol. I will order another set and update this thread if that resolved or not, who knows I may still have another leak.

Thanks everyone!

 

[Charles (in GA)]

Put the gauge straight on the pump. I bought a new vac pump because I thought the old one was giving out, pulled very little vac, or so it seemed. Then the new one seemed to do the same thing, and I finally put my old R12 gauges on the pump and it pulled a perfect vac. Discovered my low side gauge was not working correctly below zero.

Charles

 

[Tarheelgarage]

micron gage is only accurate way to determine vacuum level and how much moisture is in system. HVAC pros use this all the time...or should...if they are a pro and not a hack.

 

[zmaxmotorsports]

micron gage is only accurate way to determine vacuum level and how much moisture is in system. HVAC pros use this all the time...or should...if they are a pro and not a hack.

Ive got more years in the mechanical trades electrical/hvac and plumbing than most,Ive never used a micron gauge .
Ive got systems that I installed close to 30 years ago that are still running without any leaks,does that make me a hack?

 

[zmaxmotorsports]

Are you sure your gauges are actually screwing down all the way onto the shrader valve?
There are some 410a systems that require an adaptor between the 410 hoses and the shrader valve to make them work.
Ill post a picture of that adaptor here in a second.

 

[danski0224]

A micron gauge is the only way to measure the vacuum.

The analog or digital gauges may read 29.9 and the micron gauge will show 12,000. Lots of people do the "run the vac pump for 30 minutes" thing, but it isn't the correct method.

Installation instructions typically specify 450 microns, which is unreadable without a micron gauge. If nothing else, not using a micron gauge means the system is not installed to manufacturer specifications.

 

[jad3675]

If you want to eliminate the hoses from the equation, make your own out out of 1/4 copper. Buy 4 flare nuts from home depot, and make up a set of hard hoses. They'll be a bear to move around, burr they'll be leak free.

 

[joel63]

A micron gauge is the only way to measure the vacuum.

The analog or digital gauges may read 29.9 and the micron gauge will show 12,000. Lots of people do the "run the vac pump for 30 minutes" thing, but it isn't the correct method.

Installation instructions typically specify 450 microns, which is unreadable without a micron gauge. If nothing else, not using a micron gauge means the system is not installed to manufacturer specifications.

^^^^This is absolutely true!

But, many will always question it without truly understanding the process of evacuation of refrigeration systems. (or caring enough to learn understand it)

Hard hat on.

 

[Jackfre]

I'm with Zmax. I think you may need the adapters for the 410a hoses. I know I need them for all my Fujistu's. The standard hose will not make up to the service valves. Your local refrigeration supply house will have them.

 

[LS6 Tommy]

If you're not sure of the Schrader valves depressing properly, try something like this:

http://www.yellowjacket.com/product/715

I've been using them for evacuation for years. They really help pull down quicker. They're also indispensable for replacing bad Schrader valves.

Tommy

 

[joel63]

If you're not sure of the Schrader valves depressing properly, try something like this:

http://www.yellowjacket.com/product/715

I've been using them for evacuation for years. They really help pull down quicker. They're also indispensable for replacing bad Schrader valves.

Tommy

Don't ever go to a job without this handy tool.

 

[jonathan75]

I didn't want to spend the money on a micron gauge also. But after so many people said buy it and I used it I was glad I did. Something nice about knowing what exactly is going on. It really gives you a piece of mind. It was only around $150 on Amazon. Here is a link to my thread on page 3 where I used the gauge.

http://www.garagejournal.com/forum/showpost.php?p=3988846&postcount=57

 

[nexusroot]

Hey sorry I stopped replying here, I didn't get any email notifications on any of those messages. I just wanted to update and say I went with Yellow Jacket manifold set and it worked immediately, without issue. I'll try to respond to the remainder:

Put the gauge straight on the pump. I bought a new vac pump because I thought the old one was giving out, pulled very little vac, or so it seemed. Then the new one seemed to do the same thing, and I finally put my old R12 gauges on the pump and it pulled a perfect vac. Discovered my low side gauge was not working correctly below zero.

Charles

Yeah that's what seems like what happened to me, I have the feeling it was pulling vacuum but it wasnt actually reading on the low gauge. I tried my best even when pressurized to spray the gauge and all the fittings and saw no soap/air bubbles.

micron gage is only accurate way to determine vacuum level and how much moisture is in system. HVAC pros use this all the time...or should...if they are a pro and not a hack.

Yes yes a micron gauge would be nice. I usually have a rule, unless absolutely needed, the second time I want a tool for a job and don't have it - I buy it. So perhaps next time, although a lot of the installs I read about prior did not mention using one.

Ive got more years in the mechanical trades electrical/hvac and plumbing than most,Ive never used a micron gauge .
Ive got systems that I installed close to 30 years ago that are still running without any leaks,does that make me a hack?

lol

Are you sure your gauges are actually screwing down all the way onto the shrader valve?
There are some 410a systems that require an adaptor between the 410 hoses and the shrader valve to make them work.
Ill post a picture of that adaptor here in a second.

Yes I had to get the 1/4 to 5/16 adapter you speak of, in fact I got two, they were both screwed down and activating the schrader valve; as I could clearly pull some vacuum on the lineset (noticed when disconnecting it), and likewise when pressurizing it.

A micron gauge is the only way to measure the vacuum.

The analog or digital gauges may read 29.9 and the micron gauge will show 12,000. Lots of people do the "run the vac pump for 30 minutes" thing, but it isn't the correct method.

Installation instructions typically specify 450 microns, which is unreadable without a micron gauge. If nothing else, not using a micron gauge means the system is not installed to manufacturer specifications.

Yes this seems like a heated debate, however I will say according to the installation instructions that came with my mini slpit - a micron gauge is not mentioned anywhere in it. In specifications for pulling a vacuum it says "-76cmHG for 15 minutes or more", which is about -29.9inHg. So it was definitely installed to manufactured specifications without using a micron gauge.

If you want to eliminate the hoses from the equation, make your own out out of 1/4 copper. Buy 4 flare nuts from home depot, and make up a set of hard hoses. They'll be a bear to move around, burr they'll be leak free.

Hah yeah I suppose I could've done that. I ended up testing the old manifold set with the hoses and it wasnt them, but this would've been a good thing to try.

^^^^This is absolutely true!

But, many will always question it without truly understanding the process of evacuation of refrigeration systems. (or caring enough to learn understand it)

Hard hat on.

It would've made attaching to a vacuum pump or refrigerant tank slightly more cumbersome, but I guess as long as you're careful.

I'm with Zmax. I think you may need the adapters for the 410a hoses. I know I need them for all my Fujistu's. The standard hose will not make up to the service valves. Your local refrigeration supply house will have them.

Yeah I was using the 5/16 to 1/4, I couldn't do anything without the adapter.

If you're not sure of the Schrader valves depressing properly, try something like this:

http://www.yellowjacket.com/product/715

I've been using them for evacuation for years. They really help pull down quicker. They're also indispensable for replacing bad Schrader valves.

Tommy

Yeah I considered one of those instead of the adapters I bought originally, mainly just for the shutoff functionality.

I didn't want to spend the money on a micron gauge also. But after so many people said buy it and I used it I was glad I did. Something nice about knowing what exactly is going on. It really gives you a piece of mind. It was only around $150 on Amazon. Here is a link to my thread on page 3 where I used the gauge.

http://www.garagejournal.com/forum/showpost.php?p=3988846&postcount=57

Thanks for the recommendation, I'll save the vg200 to my AZ tools wishlist.