Copeland Scroll Advanced Protection Problems

I need help on a Carrier Gemini series split system heat pump (38ARQ). It has the Copeland Scroll with Advanced Protection System that allows the scroll to unload when high discharge gas temps are encountered. My proble is we have two identical units, one ok and the other the compressor is "unloading". We've cleaned everything, checked airflow, recovered and recharged by weight. After a few minutes of running the compressor will "unload" and continue to run. The pressures do not seem extreme and it has puzzled us. Anyne had this problem with the Copeland Scroll? I feel maybe the thermal disk in the comprssor is defective and allowing the compressor to unload prematurely. Any ideas? Thanks, Dwayne

Sorry but it has to be asked...

-What refrigerant is it working on?
-Discharge temp?
-Discharge pressure?
-Liquid temp?
-Suction temp?
-Suction pressure?
-Current draw?

And so on...

Quote:

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Originally Posted by dwayne

I need help on a Carrier Gemini series split system heat pump (38ARQ). It has the Copeland Scroll with Advanced Protection System that allows the scroll to unload when high discharge gas temps are encountered. My proble is we have two identical units, one ok and the other the compressor is "unloading". We've cleaned everything, checked airflow, recovered and recharged by weight. After a few minutes of running the compressor will "unload" and continue to run. The pressures do not seem extreme and it has puzzled us. Anyne had this problem with the Copeland Scroll? I feel maybe the thermal disk in the comprssor is defective and allowing the compressor to unload prematurely. Any ideas? Thanks, Dwayne

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It not works on pressure. It works on discharge temperature. What is your measured discharge temperatures when this happening? Check the oil level!
http://www.emersonclimate.com/contra...p_overview.pdf

dwayne,

As the others have noted, we need more information to help diagnose the problem.

A good place to start would be to tell us the measured discharge line temperature 6" from the compressor.

Here is the link to Copeland's information on the ASTP.

http://www.emersonclimate.com/contra...p_overview.pdf

Hi Dwayne.
Just A thought, but on some Scroll Applications particularly where they have "economised vapour injection".
Fitting of a discharge temperature stat is recommended.
This is over and above the normal internal High Discharge temp stat that is fitted.

Therefore is an extra one fitted and have you checked it?

Cheers Grizzly

For the compressor to unload there must be high discharge temperatures. There is a little disc in the side of the discharge line, that blocks a line back to the suction side. When it is exposed to prolonged high discharge temps it pops opening the line, subsequently disengaging the scroll. But the motor stays running. When it cools down it re-engages.

Check your discharge temperatures against the other compressor, if the are the same the disc is possibly faulty. Otherwise there is something wrong with that system. High discharge temps are usually caused by low sution pressures. Check the expansion device.

Hai friends I had same problem in our copeland scroll compressor,but I overcome the problem by pouring water on the compressor while charging gas.When charged a constend amount of gas about 40psi then stop the pouring water.Now our mechine is working good.Please try this technique to solve the problem BY SHYJU

What is the suction pressure? At very low suction; scrolls get overheated (As it won't gets oil mist lubrication). Just verify that also

Quote:

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Originally Posted by shyju

Hai friends I had same problem in our copeland scroll compressor,but I overcome the problem by pouring water on the compressor while charging gas.When charged a constend amount of gas about 40psi then stop the pouring water.Now our mechine is working good.Please try this technique to solve the problem BY SHYJU

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That is wrong procedure since you are not allowing protection device to act, and in same time, overheating and damaging compressor scrolls.

System should be charged with liquid refrigerant to high side (preferably to liquid receiver if present), with compressor OFF, until about 70% of system charge is in (if possible), and then rest of charge slowly in suction side by metering liquid refrigerant by manifold gauge or special Kwik Charge tool while compressor is ON, and at same time monitoring discharge temperature is no higher than 110-115°C.