[Techman9]

Since this is my first post here many may be hesitant to help. I have been working in the fields of HVACR for 15+ years now, but I have never had a call fight me as much as this one is.

Carrier 50BB-028 packaged unit. Watercooled and factory modified for heat pump operation. Unit was in disrepair and needed a few parts, timer, contactor, TEX and the usual filter-driers.

Made all my repairs and pressure tested ok. Hooked up my vac, not through gauges and I use a Appion valve now as my YJ's always seem to leak, and a UEI mircon gauge. This combo has worked many, many many, times in the past with no issue. Left the evac on overnight and came back today and gauge was hovering around 1700, but I was getting large fluctuations of up to 2250.

Now figuring as the other stage of this unit is completely contaminated with what appears to be water, and the stage I am working on has a newer compressor and also a suction line dryer installed (not OEM) I was thinking I have or there has been a moisture issue. So I completed a dry nitro evac, twice!

I left an evac on the unit for about 6hrs and came back to it again hovering around 1700 with the large fluctuations.

Now I have worked on some pretty neglected equipment over the years, and have had air-cooled chillers take days to get down below 500 because of the system being exposed to atmosphere, but this being a medium size unit, I'd figure it would take overnight.

My thoughts its moisture in oil or is there just that much non-condensibles in the system and its going to take a couple days. Then I started to think now why did I have lowish suction and tripping on HP. I may have made a bad diagnosis and assumed the TEX, when it may have been non-condensibles the whole time....

Thoughts on this?

 

[fitzyfitta]

Have you changed the oil in your vac pump? Just a thought.

 

[Techman9]

Yes, new before I started yesterday and again today.

I thought it may have been my pump, so I tested it out on one of my empty recovery tanks and it pulled right down......

 

[BBeerme]

Left the evac on overnight and came back today and gauge was hovering around 1700, but I was getting large fluctuations of up to 2250. Thoughts on this?

You could simply have a leak in the system. The fluctuations could indicate oil, water, or other debris around the leak area.

It would be a very small leak. You could break the vacuum with R-22 to zero psig then pump it up to 300 psig with nitrogen. I use the H-10G leak detector. Hasn't been a leak I couldn't find. Yet. [Probably just jinxed myself, heh heh]

By the way, that H-10G will detect one half of one ounce per year leak. Or something like that.

 

[Techman9]

I had 200psi (ran out of nitro) on it today and went thru 2 bottles of Big Blue spraying everything. I had the test on for one hour hooked up to my AK900 digital gauges and it did not even move 1 psi.

My next step was going to either try my other vac pump (Super Evac 11cfm) but its on a 120t chiller for the weekend. And then next would be adding some 22 to the mix and using my electronic detector.

I had something similar happen in the past on a much smaller system and it was bad hose o-ring only under vac, so I changed the o-rings too today.

I'm just frustrated about this as this is a new customer and I think they are starting to think I don't know what I am doing.....

 

[timebuilder]

One of the most useful leak detection tools I have ever owned is my Amprobe ULD-300 Ultrasonic leak detector.

It is not cheap, but it recently proved its worth once again, on a Lennox L series unit, about 10 years old. I could pump it up with Nitro and it did not budge on my AK 900's. Of course, I only waited 30 minutes or so, and then I decided to get this tool out of the truck and up on the roof.

I had to crank up the sensitivity, but once I did, I could hear just the slightest disturbance along the edge of a condenser coil. I removed the sheet metal around the coil and was able to zero in on a single bend. Putting Big Blu on it helped as I rubbed my finger over the bend, and sure enough, a small, slow bubble began to form. It made NO bubbles until I put my finger on it.

I cleaned the bend with a wire brush and a small hole appeared, and then I could feel the Nitro rushing out.

It was easy to fix, but without the ultrasonic, I might never have found that leak that day.

Perhaps I could have found it with my D Tek Select and some 22....

 

[syndicated]

Sounds like moisture to me. I spent 7 full days evacuating one circuit of a carrier split that we had to pipe while it was snowing. Changed the oil twice a day and she eventually came down to 450 and held under 1000, but it was stuck at 1800-2200 for 5 days.

 

[itsiceman]

One of the most useful leak detection tools I have ever owned is my Amprobe ULD-300 Ultrasonic leak detector.

It is not cheap, but it recently proved its worth once again, on a Lennox L series unit, about 10 years old. I could pump it up with Nitro and it did not budge on my AK 900's. Of course, I only waited 30 minutes or so, and then I decided to get this tool out of the truck and up on the roof.

I had to crank up the sensitivity, but once I did, I could hear just the slightest disturbance along the edge of a condenser coil. I removed the sheet metal around the coil and was able to zero in on a single bend. Putting Big Blu on it helped as I rubbed my finger over the bend, and sure enough, a small, slow bubble began to form. It made NO bubbles until I put my finger on it.

I cleaned the bend with a wire brush and a small hole appeared, and then I could feel the Nitro rushing out.

It was easy to fix, but without the ultrasonic, I might never have found that leak that day.

Perhaps I could have found it with my D Tek Select and some 22....

You can also test for leaks with a Ultrasonic Detector while you are pulling vacuum

 

[timebuilder]

You can also test for leaks with a Ultrasonic Detector while you are pulling vacuum

Yes, I've done that as well. Depends on how the leak is configured. A vacuum can sometimes pull the leak shut...

 

[Poodle Head Mikey]

I would change the oil in the system compressor and also change the oil in the vacuum pump.

R-22 is a little pricy but a few lbs. will make a better sweep than nitrogen I think.

It's not condensibles - they were gone in the first hours. Does the valved-off vacuum rise to a point and then stop? Or does it continue to rise?

PHM
-----

Since this is my first post here many may be hesitant to help. I have been working in the fields of HVACR for 15+ years now, but I have never had a call fight me as much as this one is.

Carrier 50BB-028 packaged unit. Watercooled and factory modified for heat pump operation. Unit was in disrepair and needed a few parts, timer, contactor, TEX and the usual filter-driers.

Made all my repairs and pressure tested ok. Hooked up my vac, not through gauges and I use a Appion valve now as my YJ's always seem to leak, and a UEI mircon gauge. This combo has worked many, many many, times in the past with no issue. Left the evac on overnight and came back today and gauge was hovering around 1700, but I was getting large fluctuations of up to 2250.

Now figuring as the other stage of this unit is completely contaminated with what appears to be water, and the stage I am working on has a newer compressor and also a suction line dryer installed (not OEM) I was thinking I have or there has been a moisture issue. So I completed a dry nitro evac, twice!

I left an evac on the unit for about 6hrs and came back to it again hovering around 1700 with the large fluctuations.

Now I have worked on some pretty neglected equipment over the years, and have had air-cooled chillers take days to get down below 500 because of the system being exposed to atmosphere, but this being a medium size unit, I'd figure it would take overnight.

My thoughts its moisture in oil or is there just that much non-condensibles in the system and its going to take a couple days. Then I started to think now why did I have lowish suction and tripping on HP. I may have made a bad diagnosis and assumed the TEX, when it may have been non-condensibles the whole time....

Thoughts on this?

 

[Techman9]

I stop the vac and it holds, thats why I don't think I have a leak. I ran out of vac oil today as well so I can't get any until Tuesday. I will check in on it Monday and see how it is....

 

[Nuclrchiller]

Does the valved-off vacuum rise to a point and then stop? Or does it continue to rise?

PHM
-----

A good question. The answer to this can help determine if water, or ice, exists in the circuit. I'm pretty sure that's why PHM asked it. Let the vacuum stand overnight before you answer this.

 

[Techman9]

So today I was able to switch out my vac pump because the chiller was pulled down on my other job.

This trouble system was at 1700 again. Switched pumps and system already pulled under 800 in about 15mins.

I guess I have a bad pump even though with just a mircon gauge hooked up to it, it pulls right down.

 

[gravity]

Where is your micron gauge? On the pump or the system?

Sent from my SM-N900V using Tapatalk

 

[Techman9]

on the system of course. Attached to my appion Schrader removal tool. System is charged and working perfectly