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-   -   New Compressor - Wrong Charge? (http://www.diychatroom.com/f17/new-compressor-wrong-charge-24326/)

shayneb 07-27-2008 09:35 AM

New Compressor - Wrong Charge?
 
Recently, our A/C broke. A shorted compressor motor in the outside condenser unit was to blame. It is a Goodman CKL42-1A, which uses a Copeland compressor and we engaged an A/C serviceman who does weekend work to swap it out and get it working correctly. The installation has been less than satisfactory because the compressor unit does not always start when it should - the compressor sometimes starts along with the fan on the condenser unit, and sometimes only the fan. It took from yesterday noon to last night to reduce the house temperature from 74 to 69 - this usually happened within about 30 minutes.

The old compressor is a Copeland CR42K6-PFV-230 and the new unit is a CR41KQ-PFV-980WB. I have the specs from emerson as PDF files and can send if required. Sound close enough? The specs on the units seem very similar. We don't need the heater though on the new one so it is left disconnected. Very close physical footprint and it bolted in OK.

He swapped out the compressor unit after he removed the R22 with a special unit that attached. After evacuating the old R22, attached a vacuum unit, then disconnected the old compressor, re-connected the new one and welded the new pipe-work in. He leak tested with a spray foam bottle on the newly welded pipes, found one leak and re-welded it. No nitrogen inserted to test for leaks though.

After obtaining a vacuum, he then put in the R22 in the system. The amount of R-22 put into the system was not measured and this was a red-flag for me. I believe the specs are about 6 pounds but he had no way of really knowing.

The unit was started and seemed good. Cool air started flowing into the house and there was a 17 degree variance between house temp and cool air that was in the late 50's. The temp in the house was about 74 to begin and we had the thermostat set to 66 to get it cooling. After a short while and his last minute adjustments, the compressor tried to start again- we heard the short buzz but the compressor unit did not start but the fan on the condenser unit mounted above the compressor did.

After much fiddling, he measured the compressor unit and told me the internal overload in the compressor was coming on (opening the internal protective circuits?) apparently to stop the compressor from overload. Weird. Then he evacuated a little R22 and tried again. Still no good.

After an hour or more he departed saying the compressor was probably bad. Remembering it is brand new, purchased from a reputable local agent of Emerson this seems strange.

The thermostat inside was set to 69 and reading about 74 wen we turned the a/c on about 1 or 2PM. It came down only a degree every few hours. Overnight the temperature in the house has come down to 69 as it should, but we have a cycle of the condenser sometimes running without the compressor running and sometimes with.

We were shown that the compressor unit draws 16.2 amps running and I was told that the pressure is 210 PSI and the suction side is 60PSI. I do not know what the grade or spec of the coil in the basement where the ducting and furnace are, or whether that even matters as with the old compressor it worked just fine.

So we are left with the new compressor installed, the remainder of a brand new 30 pound bottle of R-22, and an A/C that "nearly works" properly, but the compressor not always starting is of concern. When the compressor tries to start the fan outside runs for a period (as if it is functioning), then the compressor kicks in, cools and turns off.

I am not an A/C expert, but I have done some reading online and thought about what the potential causes might be and possible fixes.

1. When the compressor was installed, could the unit have been damaged by his welding (overload protection opening periodically not allowing compressor to start?) He spent a long time heating the pipes. I solder and weld myself and it took him a long time heating pipes on a nearly empty bottle, which he had to go and replace. Could heat transfer have damaged the compressor?

2. Need to install hard start kit? He did try another capacitor but it made no difference. He tried what he called a hard start kit, which just seemed like a different value of capacitor, but that made no difference.

3. Could the charge be wrong so the system is out of balance and causing problems? After online research, it seems there should be a scientific approach to charging the system. Would a wrong charge cause the compressor protection to cut in. Would this happen quickly with a wrong charge?

4. Could is be a power supply thing? The lights flicker when the compressor unit starts. Unlikely but possible?

I am looking to work with an honest and competent service tech who won't rip us off, hence all of the detail above.

Thanks

8 Ball 07-27-2008 01:07 PM

Lets see the pdf files. Was the old compressor a "burn-out"? Your charge sounds like its incorrect now, after fidling with it.

Was a new start kit installed that matches the new compressor?

Are the compressor wires on the right posts..C,S,R ?

Mikeee 08-20-2008 08:23 PM

AC problem
 
If your outdoor unit is over 10 years old it may have been better to replace the whole thing.What it cost you in repair hours would close to pay for a new unit. I am in the same situation with one but warrantee is buying the compressor.

kb3ca 08-22-2008 02:26 PM

New Compressor - Wrong Charge?
 
Have you checked the points on the contactor, the relay that provides 240 volts to the compressor? If one half of the contactor is not making good contact then the fan may run but the compressor will not start.
Just a thought.

biggles 08-23-2008 08:13 AM

the compressor is single phase 240V check that old contactor should of been changed if it was a burnout contacts might be shot.being single phase(like a refrig or window unit) the unit needs time to equalize pressures before another cooling cycle. if it tries to start before the pressures don't balance off it will trip the OL and that is his reasoning to put a hard start kit on a new compressor...he is forcing the compressor to push for a start against the unequalized pressures causing higher amps heat and the OL trip(hand on the compressor tooo:eek: hot to touch) and then possibly add the factor of an over charge and your looking at major problems.he should of weight out the burn gas and changed the liquid line dryer and reinstalled the same gas amount in LBS new out of the can you have.a new compressor won't change the charge amount on a change out and as for the heat and repipe the compressor should a survived the brazing...how long did he pull a VACUUM:whistling2: if he actually did which would multiply you problems.that was a crankcase heater he didn't reinstall it must be on the compressor or unless the new one came with an insert one?TRY THIS and give us the result shut the main dissconnect at the condenser and go inside set the stat to cool (lowest setting)now your out at the condenser grab the uninsulated line(liquid line) and turn the power on the condenser...how warm...hot does that line get after 2-5 minutes running this with the comp/condenser running if it get hot real fast your over charged and (that VACUUM) if not done or half done you could have moisture and or non-condensibles within the system...i will check back on the quick test latter


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