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Noise in the High pressure line


Jeff Beck
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York 3 ton ac system, seems fairly new. There is a squeaking noise coming from the high pressure line.

System seemed to be cooling correctly except for the noise. It sounds similar to a piece of paper vibrating in the breeze in the duct work but both the client and I could hear it coming from the liquid line.

I couldn't find any areas where the line was rubbing against something else although it wasn't possible to trace the line all the way back to the compressor.

Could this be an indication that the refrigerant level is low?

Thanks,

Jeff Beck

Foresight Inspection Service LLC

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When you say a single unit what do you mean? Was it a typical split system, furnace inside condensing unit outside?

I ran into a liquid line that started to "sing" but the condensing unit sat a few stories above the air handler. This was due to a velocity problem - If I remember correctly we had to add small restrictors to the discharge valves on the valve plates (Carrier semi-hermitic recip)

Typically if the unit is low on charge you hear gas/liquid movement in the liquid line. When the unit is fully charged the liquid line remains pretty silent for the most part. It may have had some type of restriction although these occur most often around the liquid line dryer. You can visually see these - right after the point of restriction the liquid line will start to ice because the restriction is acting like a metering device so to speak.

Did you feel the liquid line? Typically it should be warm to the touch but not hot - if it was really cold then it most likely is low on gas.

The more I think about it the more it sounds like a discharge valve vibration....

Got a model number?

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When you say a single unit what do you mean? Was it a typical split system, furnace inside condensing unit outside?

I ran into a liquid line that started to "sing" but the condensing unit sat a few stories above the air handler. This was due to a velocity problem - If I remember correctly we had to add small restrictors to the discharge valves on the valve plates (Carrier semi-hermitic recip)

Typically if the unit is low on charge you hear gas/liquid movement in the liquid line. When the unit is fully charged the liquid line remains pretty silent for the most part. It may have had some type of restriction although these occur most often around the liquid line dryer. You can visually see these - right after the point of restriction the liquid line will start to ice because the restriction is acting like a metering device so to speak.

Did you feel the liquid line? Typically it should be warm to the touch but not hot - if it was really cold then it most likely is low on gas.

The more I think about it the more it sounds like a discharge valve vibration....

Got a model number?

This is the model number: GY95100C16UP11H.

Sorry, I should have said it was a split system.

The liquid line was kind of warm and not what I would consider cold.

I thought about a restriction but don't remember seeing any but I didn't look for a line dryer. In fact, I'm not sure I'd recognize a dryer. Would that be at the compressor cabinet?

It sounds as though the system is low on refrigerant or at least that would be the place to start.

Thanks for your help Terrence I really appreciate it.

Jeff

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Tried to go to York this morning but the residential site is down.

This link http://images.google.com/images?hl=en&s ... f&oq=&aqi= will show what liquid line dryer look like.

If this is a newer system it may not even have one installed - depends on what kind of mood the installer was in.

Also, if it is a newer system, that uses R-410/Puron, the pressures on these systems are much higher than R-22 systems.

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  • 2 weeks later...

May i make an un-educated guess? I dont know a huge amount about A/C's, still trying to learn, but there is oil that mixes with the freon in the pressure lines right? If so, could it have a small leak, low on oil and the piston is rubbing?

Sorry, just a guess.

The filter Dryer is normally right outside the condensing unit if im not mistaken, also I think I have heard thier more common on large units then smaller ones, although im not sure what they were callign large, 6 ton? 8 ton?

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