New Install Having Compressor Issues See Video

charliechicago

Hello to all
I installed a new air handler and condensing unit at beginning of the summer. Flushed lines, pulled vacuum and charged. The customer would sometimes hear a noise from the condensing unit, sometimes the temp went up in the house and sometimes it was ok. I went to the house 4-5 times. One time the compressor was overheated, but usually when I got there 20-25 minutes later it was running. Not sure if it overheated and reset or just started to work again. I left a single gauge on the high side of the unit so he could take a look when it happens and finally after one month of working fine it happened twice yesterday. The unit makes a very loud rumbling noise and one time it was stuck at 200 PSI (410A system) and one time it was at 250 PSI and fluctuating a little. Thats less then standing pressure as its 90 degrees. Any suggestions?
I tried to attach a video but it does not seem to work. Can a video be added to this forum? I think it would be good to see the video.
Thanks, Michael.

mattmia2

Oil slugging and preventing vapor or refrigerant from flowing somewhere?

What is the refrigerant control?

ChrisJ

I would upload the video to youtube and post a link.

If the compressor is overheating, and that low highside pressure makes me think it's undercharged or something is funky with the metering device. Can you share pictures of the install? Does it have a TXV? Where's the bulb located etc?

For R410A I'd expect to see a high side of 275-325 PSI.

What's the SH and SC?

Ironman

Have you checked that everything electrical is correct? Wiring, Voltage, amp draw, capacitors?

clammy

Sounds like your under charged , what is the metering device on the indoor evap ? Did you take a sub cooling and super heat measurements, if the compressor is shutting off on temp then u have no superheat and are under charged . If you have a expansion valve on the coil you can start off w 10 degreee sub cooling or better yet look on the condensers tag , they will usually give you a recommended sub cooling . Usually on 410 where running 300 and upwards depending on the load and how hot it is outside . Re check your charge Peace and good luck clammy

pecmsg

Are there high and low pressure safety’s on the condensing unit?

Could be a pressure relief letting go.

charliechicago

I am posting a video of the compressor. Make sure the sound is on to hear the noise. The system is charged properly, 12 sub cool. Runs great when it works. Voltage and amperage are good when it runs properly. You will see in the video I left my amp meter on and it shows 5.6 amps or so, but Im not sure it was reading properly because it shows microamps in the bottom corner. Thanks.
https://drive.google.com/file/d/1kWT7C-q1VhFfvzWRlRpFTv8aqfksXd5H/view?usp=sharinghttps://drive.google.com/file/d/1dTRXBfYS1QgKfKtxHQZsCrkb6FCZ9XbV/view?usp=sharing

charliechicago

Second video
https://drive.google.com/file/d/1dTRXBfYS1QgKfKtxHQZsCrkb6FCZ9XbV/view?usp=sharing

unclejohn

Maybe it's running the wrong way. Meaning the compressor is spinning backwards.

charliechicago

Can a single phase compressor run backwards?

mattmia2

It is reading milivolts according to the display. i have had the contacts i the mode switch of cheap multimeters get dirty and make intermittent contact and had them read the wrong function or some combination of functions so that current reading is a bit suspect. What is the ratings plate current? ~1500 w seems low for any condenser.

Look at about the 4th from the last post here from @EdTheHeaterMan for the formula to measure the capacitance of the motor capacitor using the voltage and current through the capacitor and compare to the marked value, perhaps it is weak:

https://forum.heatinghelp.com/discussion/180290/capacitor-testing#latest

ChrisJ

Can't help you if you don't answer the questions ....

Does it have a TXV and if so where is the bulb installed?


What's the lowside doing? What's the superheat?

subcooler_65

You're not moving refrigerant. You are flooding the condenser and the compressor is bypassing. You have a restriction in the system, most likely the metering device.

charliechicago

Valid point Chris J
It’s a txv, like I said 12 Degree sub cool. It’s a heil, txv comes strapped inside, it is still right where is was originally. Don’t know the low side or sh. I know, how can you troubleshoot without info. The problem is it happens when I’m not there and then corrects itself before I can get there. I only attached, to the high side, one of those single gauges that you can leave on the unit for pressure testing. That’s all I had.
It seems to not be pumping or very little, at 250 psi and 90 out. I’m thinking closed txv or something with the compressor. I had checked the capacitor and was fine. Could change it.
But what’s with the noise? Closed txv I don’t think would do that. Maybe a chattering contactor?

charliechicago

I hear you subcooler65

Ironman

charliechicago said:

Can a single phase compressor run backwards?

Yes, if the start and run windings are wired in reverse.

ChrisJ

Need to know what they lowside is doing and need to know tht bulb location. If the bulb was installed for vertical and it's installed horizontal etc it could be wrong. Was it ragged off when brazing?

Is it even strapped to the pipe?

Did your flow nitrogen while brazing?

pecmsg

> @Ironman said:
> (Quote)
> Yes, if the start and run windings are wired in reverse.

Won’t happen
Start and run are the same phase

ratio

Would try to run backwards, but likely burn out the start windings pretty quickly. Unless it's a Bristol, then it'd run at IIRC 50% capacity.

mattmia2

Does it do it only from the beginning of a cycle or can it start during a cycle with the compressor already running??

charliechicago

Mattmia2
That’s a good question. I have a feeling it happens at the beginning of the cycle, although I can’t be sure. One time the customer called me and five minutes later when I called him back he said the noise went away already and was running fine which might mean it only happens on startup.

mattmia2

Ok. Does it sometimes start working properly in the middle of a cycle?

charliechicago

I don’t know.

EBEBRATT-Ed

By now the compressor is probably toast. Shut it down check everything and start from scratch

Ironman

pecmsg said:

> @Ironman said:

> (Quote)

> Yes, if the start and run windings are wired in reverse.



Won’t happen

Start and run are the same phase

Paul,
Yes it will. The run capacitor alters (shifts) the phase of the winding it's connected to causing it to act like another phase.
If you have, or had, an Annie compressor tester this is what it would do (reverse the rotation) to free a stuck compressor.

mattmia2

Ironman said:

pecmsg said:

> @Ironman said:

> (Quote)

> Yes, if the start and run windings are wired in reverse.



Won’t happen

Start and run are the same phase

Paul,
Yes it will. The run capacitor alters (shifts) the phase of the winding it's connected to causing it to act like another phase.
If you have, or had, an Annie compressor tester this is what it would do (reverse the rotation) to free a stuck compressor.

I recall somewhere in "Modern Refrigeration and Air Conditioning" it saying to wire the compressor like this to unstick it.

unclejohn

This can happen.
A less likely possibility for reverse running is one that occurs for single-phase motors. In this instance, the
rotor must have a certain amount of rotational speed in the reverse direction before power is applied. This can occur
during a momentary loss of power to the compressor motor (e.g. power flickers during thunderstorms). Since the
pressure differential across the scrolls can quickly drive the crankshaft in reverse, when power is reapplied the
compressor may continue to run backwards. When this occurs, the motor will only run for a short amount of time
before the motor protector will stop the motor. Since the compressor will restart in the forward direction, the
potential for damage is less significant.

unclejohn

So did you get to the bottom of it?