Replace evaporator coil

[Cool Change]

Hi guys,
Im new in the industry and new on this site.
I installed an evaporator coil in an upflow unit. After charging with a few pound of r22 and turned on the ac to start doing superheat and subcool reading to adjust the freon levels I noticed a hissing sound near the line drier I installed about 4 feet from the air handler. The unit was holding pressure when I tested when I pressure tested with nitrogen and I maintained pressure in the gauges so I am sure it is not a leak. I am wondering if I got too much solder in the line and that is causing an obstruction in my attempt to make sure I had good joints. Tell me what you think

[second opinion]

Hi guys,
Im new in the industry and new on this site.
I installed an evaporator coil in an upflow unit. After charging with a few pound of r22 and turned on the ac to start doing superheat and subcool reading to adjust the freon levels I noticed a hissing sound near the line drier I installed about 4 feet from the air handler. The unit was holding pressure when I tested when I pressure tested with nitrogen and I maintained pressure in the gauges so I am sure it is not a leak. I am wondering if I got too much solder in the line and that is causing an obstruction in my attempt to make sure I had good joints. Tell me what you think

How would you get to much solder in the joint?

[TACKERDOWN]

I think that would be an awful lot of solder if you have a restriction it should show up on your gauges

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[Cool Change]

Not sure, was just thinking maybe some dripped into the pipe. I pushed a lot in there. Was reaching I guess because I didn't know any other reason there would be a hissing sound other than a leak which it is not.

[PM Heat n Cool]

If you have a restriction you would notice a temperature drop across the drier not to mention probably see something in your pressures superheat and subcooling.

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[Cool Change]

I probably used a quater stick

[Cool Change]

I had to shut it down for the day but I was getting only 45 pounds on the low and about 80 degrees before I left so I was very confused

[foobee]

try pressuring the unit back up and soap bubble your weld joints

[TACKERDOWN]

I probably used a quater stick

you should only need as much as it takes to wrap around the pipe

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[Cool Change]

Ok, I will again. I did hold 100 pounds of nitrogen and soap bubbled the joint before adding freon

[Cool Change]

you should only need as much as it takes to wrap around the pipe

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Yes I know your right about that but since it was my first time soldering since school and my first real job I was a little paranoid and jammed a lot in there

[PM Heat n Cool]

80 pipe temp

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[Cool Change]

Do you have any other ideas on the hissing sound

[Cool Change]

Yes, suction was reading about 80

[TACKERDOWN]

possibly improper charge

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[Cool Change]

Yes, the suction side was reading about 80 degrees and 45 pounds pressure

[PM Heat n Cool]

How is the subcooling

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[AddMore22]

A few questions for you....

1. Did you pull a vacuum? how many microns?
2. Does it have a TXV?
- If not did you put piston in?
3. Did you out the drier in the correct way?


Also by adding 100 psi of nitrogen you stand a chance of not seeing the leak due to the nitrogen changing into a liquid , and therefore keeping your pressure around the same IF you had a leak.... Obviously over time it would show due to it leaking.

[bja105]

Also by adding 100 psi of nitrogen you stand a chance of not seeing the leak due to the nitrogen changing into a liquid , and therefore keeping your pressure around the same IF you had a leak.... Obviously over time it would show due to it leaking.

I disagree with that statement. 100 psig is not very high at all, and there is no way he has liquid nitrogen. The Nitrogen in the tank is a vapor at 1000 psig, and will remain a vapor at 100 psig unless he is cooling it very very very much. We use Nitrogen for leak checks because its pressure does not change much based on temperature.

You get the hissing when the system is running, correct? The hissing is probably liquid refrigerant flashing into a vapor, which should not happen in the lineset. If you have measurable subcooling leaving the outdoor unit, and there is no significant pressure drop before the metering device, this should not happen. If your lost pound of solder is clogging the filter drier, you should get a measurable temperature drop across the filter drier.

What are your subcooling, liquid line pressure, and liquid line temperature? May as well give us superheat, too. If you don't know how to find those data, you better ask some more questions.

[Baycienda]

I agree with bja105. If you suspect that there is a leak, go ahead and pressure check it again. And put in a new dryer. But if this is your first time brazing since school that sound could be a lot of things. I wouldn't eliminate it to just soldering the line set. It could easily be refrigerant making the sound. Good luck finding it.