New Trane A/C high pitched sound after shut off?

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Old 08-14-20, 08:15 AM
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New Trane A/C high pitched sound after shut off?

We just replaced our old Trane central AC with a new one. When it cycles off, I hear a high pitched sound in our bedroom that lasts for a couple of minutes and then stops. My installer said that’s the pressure equalizing and says there is nothing he can do. I saw on Reddit that this is common for Trane units. My old one didn’t do this.

This is is a split heat pump system. Will I hear this noise when the heat runs in the
winter?

Is there anything that can be done? Thanks!
 
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Old 08-14-20, 12:42 PM
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Hi, can you post a video of the noise? that may be helpful in trying to ID the sound.
Geo🇺🇸
 
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Old 08-14-20, 01:26 PM
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You're hearing that from the air handler.... inside the house.... correct ?
Trane had issues with their EEV (electronic expansion valve) making a whistling noise on system shutdown. It was due to pressures equalizing. This problem was happening five years ago and I thought they had upgraded their programming to shut the EEV valve either completely off or opening it further and then closing it.

Your Trane dealer should be aware of the problem.

Yes..... you will hear it in the winter as well and also the reversing valve in the condenser when it changes from heat to cool for defrosting.
 
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Old 08-14-20, 04:24 PM
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Pete....that’s interesting. We have two new air handlers and only one of them is causing a noise. I will ask my installer about replacing the EEV board. An HVAC guy on another forum suggested that.
 

Last edited by egruber; 08-14-20 at 05:12 PM.
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Old 08-14-20, 04:57 PM
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It's a valve in the freon line that is causing the noise.
 
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Old 08-14-20, 05:08 PM
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If it’s a valve in the Freon line, I don’t understand why I didn’t hear it with the old unit.

is it a difficult fix? Are you no longer suggesting the EEV in the air handler?
 
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Old 08-14-20, 05:17 PM
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Please re-read post 3. The EEV is a valve in the freon line in the air handler. It's job is to meter freon into the cold coil. It was mechanical. Now it's electronic. From what I understand..... that valve is making the noise. I'm not a factory trained Trane tech so I don't know what they've done to solve this issue. It is not new. It has been happening. Your tech should be able to get the problem taken care of. If not..... call Trane customer service.
 
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Old 08-14-20, 05:23 PM
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Thanks for clarifying. I spoke to my installer and was told my unit had a mechanical valve and they would follow up with Trane tech support. Is it your opinion that this valve should be replaced?
 
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Old 09-07-20, 02:57 PM
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So here is an update. Trane tech support did not suggest replacing the mechanical valve. Instead, they asked my installer to move a part that he referred to as a muffler from the outside compressor to somewhere in the air handler in my attic. The part was a 4-5 inch in-line cylinder and looked like the refrigerant ran through it.

Anyway, he did the move and it did reduce the noise, but did not eliminate it.

He is going back to Trane tech support. Any idea what should be done next?
 
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Old 09-07-20, 03:40 PM
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I wasn't aware the problem was happening on the mechanical expansion valves.
As mentioned I'm not a factory Trane tech so I'm not sure what the best course of action is.
I'll see if I can get my forum partner to comment as he works for Trane.
 
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Old 09-07-20, 03:50 PM
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Thanks. Much appreciated.
 
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Old 09-14-20, 08:36 AM
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Were you able to speak to your colleague from Trane?
 
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