Compressor motor safety alarm

[Ulderico]

I need some help on how to solve my problem with Carrier reefer 69NT40-511-52.
The reefer undergone oil change, expansion valve change, quench valve change,
filter drier change and weigh in R134A charge based on its nameplate.
After bringing the reefer back to life the freezer temperature seems dropping at first
but wont go any lower than 65degF and compressor stop with AL24 (compressor motor safety)
and it's very hot.The oil level was on the middle of compressor sightglass when not running
but i noticed that it was just like sprinkling on the sightglass when running.
Current on every phase were from 9.8A to 11A. Any opinion guys!

[The Viking]

Problems with the superheat/adjustment of the expansion valve?

You did pull a good vacuum before you added the charge?



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[Ulderico]

I think, for almost 3 hrs, I did a good vacuum. The expansion valve was fresh from the box bought from the supplier so I guess it was factory set.

[The Viking]

OK,
What we need to know in order to give you accurate guesses on what's going on is:

-Suction pressure
-Discharge pressure
-Suction line temperature
-Discharge line temperature
-Liquid line temperature, where it leaves the condensor
-Liquid line temperature, before it enters the TEV
-Ambient temperature
-Temperature inside the freezer

All the above taken as close together (in time) as possible, preferable after the system has been running for 15 minutes (but if it cut out before then...)
Also, the more accurate the measurements the better.

Happy hunting.


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[Ulderico]

@ The Viking, here are the data gathered during a 20minute run.
-Suction pressure - 10psi
-Discharge pressure - 120psi
-Suction line temperature - 59.2degF
-Discharge line temperature - 220degF
-Liquid line temperature, where it leaves the condenser - 94.8degF
-Liquid line temperature, before it enters the TEV - 78.2degF
-Ambient temperature - 85degF
-Temperature inside the freezer - 77degF

Compressor temperature is 202.5deg F

[The Viking]

134a,

10psi = -14.1ºC, 59.2ºF = 15.1ºC => 29.2K superheat.
120psi = 36.7ºC, 94.8ºF = 34.9ºC, 78.2ºF = 25.7ºC. This is interesting, the sub cooling is only 1.8K when it leaves the condensor which is a clear indication of SOG but then it cools a further 9.2K so unless you got a sub cooler externally to the condensor there is a blockage in the liquid line somewhere (drier?).

So, the super heat is way too high (it should be around 4K) and the lack of cooling from refrigerant returning to the compressor is causing the compressor to overheat.
However, before you start adjusting the TEV the charge has to be verified and the cause of the temperature/pressure drop over the liquid line identified and rectified.
(The TEV will not be able to function properly unless it got a solid liquid supply)
If you find the point where your liquid line drop in temperature you will also find the blockage.

Sorry about the Metric, it's just what I'm used to work with.

Happy hunting.



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[charlie patt]

run amps on comp not enough should be 14 amps is the condensor fan on or no ? it should not be at that head and when is the quench valve opening? ive had these overheat when the quench aint pulseing should pulse when low side hits mius 6 psi and for half hr on start up whats serial number or age has it a liquid injector?