Pentair Ultratemp 120Q randomly makes loud compressor screeching on startup and run

[liquidneba]

Hi I was wondering if anyone has advice on my Pentair Ultratemp 120Q.

First it heats without issue, but randomly on start-up (I would say once a week or so), the compressor make a loud racket on startup and keeps making a similar noise while running, the pitch and sound decreases over time, but then also increases. (Once I shut down the heat-pump and it starts back the compressor sound is normal). The fan works and sound normal throughout each start-up. I thought the rotor might be locking (might still be true, but the compressor doesn't shut down and I don't see the amps jump either).

I see via my energy monitor that the total amp draw of the fan and compressor is 34-35 amps (while making the noise and during normal startup/run). I didn't notice any spikes in the amp draw, but I also don't have an ampmeter for startup amp fidelity.

The last time this happened, I checked the capacitor, both fan and Herm (compressor) are within spec, I don't see any damaged or burnt wiring on the contactor or compressor or capacitor, or anywhere else for that matter, the voltage draw seems normal 236V on the incoming.

Any advice, before calling a tech?

Thanks!

PS I recorded the screech soon after startup for about 3 minutes (within 1-3 ft of the heater) and then shutdown the heater, with my iphone. Sound file is zip and attached below.

 

[liquidneba]

bump

 

[swamprat69]

How old is the heat pump? Is this noise something new that just started?

 

[swamprat69]

When you shut down the heater and start it back up is there a 5 minute delay before the heater restarts?

 

[liquidneba]

How old is the heat pump? Is this noise something new that just started?

We had it installed just earlier this year. It started randomly happening a few weeks ago.

 

[liquidneba]

When you shut down the heater and start it back up is there a 5 minute delay before the heater restarts?

Yes there is the 5 minute delay and it starts back up again at the same amps 34-36 (includes fan as well) and with low noise from the compressor.

Over the course of maintaining the temperature with the heat pump starting up and shutting down, eventually the screech will occur on startup and run period until I shut it down. I have a Fluke multimeter to check the wiring, capacitor, voltage, etc.

 

[swamprat69]

I asked about the time delay because a scroll compressor can run backwards (very noisy) if it attempts to start up before pressures have equalized during the off cyle. Unforunately there could be other causes for the compressor noise but a tech would have to need pressure gauges and other test devices hooked up during the time when the noise occurs. The good news is that at less than a year old both the parts and labor should be covered under warranty. Another possible cause could be liquid refrigerant flooding back to the compresssor due to an incorrect overcharge or a possible maufacturing defect in the compressor. Best to have the heater checked under the warranty.

 

[liquidneba]

Thank you for your advice (sigh)! I was hoping it would be something easy, like a dying capacitor or a loose wire.

I read a few times here that people get the whole unit swapped versus, having Pentair ordering/having new compressor installed... I'll report back on what happens.

Best!