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Discussion Starter · #1 ·
1. Exsisting unit was a old carrier semi hermetic 20-30yrs old ( lost a rod). I replaced a new Straight Cooling only Goodman 3 phase 10 SEER condensing unit with a scroll compressor
2. Replace the TXV with exact equal match. I was careful not to over heat the TXV used heat sink.
3. Flushed the lines did NOT seem to have restriction
4. good vaccuum charged the unit my pressures we a little low
55psi suction 240psi head @ 105* at start up
5. Did NOT change the air handler


The unit ran only 5-10 minutes OK before I knew it the suction shot up to 125-150psi the head stayed at 220-240psi.

I shut the unit off for 5 min the pressures did NOT equalize started the unit up again the pressure remained at 150 psi suction / 240 psi head. compressure amp draw 13.5-13.8 with in specs.
I waited a day the went back to see if the compressor was running in reverse switch the wires ran for a split second (made awful noise) switch the wires back ran great 20* split for 36hrs the crapped out again with the same simtoms I changed the compressor. I did NOt take a superheat pressures are are screwed up

lines are warm to amient to the touch
disconnected condensor fan motor for 3-5 mins NO pressure changes

1.Could I have a restriction in the TXV or TXV over feeding (faulty) or maybe by passing to the equalizing line?
2. A pluged liquid line filter factory installed in the condensing unit causing this crazy pressures in the 125-150 suction / 220-240 head? filter is up stream of service port/valve. so fast?
3. Solder in the liquid line clogging the TXV?
4. NO pressure change when I started the compressor & a little discharged gas
5. No or very little Vacuum when all gas was out of system


I changed compressors and it did the exact same thing only ran 5-8 minutes
I don't wanna change another
 

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Tech./Sales Consultant
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My first guess would be a partially blocked OEM filter/drier in the new unit. Since you used the existing coil, you would be dealing with moisture being absorbed by the oil remaining in the existing coil that did not boil off during the evacuation and that got trapped in the internal filter/drier. You need to check the subcooling to tell if this is happening.

If your subcooling is high, even if you reduce the charge to where you are starving the indoor coil, you should get rid of that internal OEM filter drier and install a new liquid line F/D in the line between the service valves of the new unit and the air handler.

You may also need to get rid of some refrigerant oil if that existing coil were filled with the old compressors oil.
 

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I'm just wondering… why didn't you also change the 20-30 year old coil as well?
Are you sure of its condition and that it is a match for the new condenser capacity? Have you examined it again while all this was going on and after the system had been running.

Is that 105* ambient temp? Jeez... if so, that has to mean a heavy evaporator load, which could explain high suction pressure. R-22, I'm guessing? 150 PSIG, that would be around 83* by my T/P chart. Your high side sounds a little low as well for a 105* day.

Are you sure this system is charged properly? it doesn't sound like it. :001_unsure:

Did you also check for temp drop and icing of lines around LL drier, TXV, etc…?

You also mentioned that the new unit was "straight cooling only", so does that mean this was originally a heat pump setup?
 

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Discussion Starter · #4 · (Edited)
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no the org was straight cooling the system is a 7.5 ton in indoor ambient temp is 80-82* out door amb. is 105*. I replaced the orginal sporlan TXV non adjustable to the orginal specs I'm gonna change it to adjustable TXV. changing the in door unit my be next option. save me alot of headach.
I should have the owner them pay for a match set. I like a challenge but man this is eating my luch. I've never experienced this problem in my 25yrs. like I saids the unit only runs 5-8 min. do copeland scolls have intergral by pass or protection that would cause the scoll to free spin.
 

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no the org was straight cooling the system is a 7.5 ton in indoor ambient temp is 80-82* out door amb. is 105*. I replaced the orginal sporlan TXV non adjustable to the orginal specs I'm gonna change it to adjustable TXV. changing the in door unit my be next option. save me alot of headach.
I should have the owner them pay for a match set. I like a challenge but man this is eating my luch. I've never experienced this problem in my 25yrs. like I saids the unit only runs 5-8 min. do copeland scolls have intergral by pass or protection that would cause the scoll to free spin.
The scrolls lift and seperate..
 

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I would change out the coil to a new matching set and how old is the airhandler maybe up grade whole system. I don't know there budget but i think it would be wise and a good sale for you good luck.
 

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I would get all of the data, especially subcooling and superheat, to see what the refrigerant is doing. You should be able to make that indoor unit work as long as there are no restrictions in the refrigerant circuit or problems with the air flow.

Have you checked the air yet? Blower wheel and coil clean? Blower motor and capacitor up to snuff?
 

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a restriction in the txv or liquid line would resemble a pump down on the guages. sounds line one of two things, either the txv is not metering the refrigerant through, only dumping it in as a hi pressure liquid, or the hi side is dumping into the lowside through the compressor. is it hissing on the off cycle? does the cold suction line get hot when the unit shuts down? wouldn't it be easier to change the txv than the compressor? well good luck with it, keep us posted!
 

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Whats the piping like. Evap below condenser? Long run? oil traps.

Those old carrier/carlyle were famous for pumping out all the oil given the slightest oportunity.

Systems low on gas. 105 deg outside ambient, whats the inside temps.
If 90 inside your head would run up nearer to 250 to 300 maybe more until inside air drops to design criteria.
Evap is oil logged due to the low vaccum stated. choke liquid line and suck it up. keep mum because it may void the warranty. Check for excessive oil in return gas. Of course I wouldnt ever do that. Nor would I use the compressor to blow it into a recovery tank.
Old comp probably failed due to bad cc heater.
TXV may be bad but most likely trying to compensate for no or low flow due to above.
Does new comp have an internal relief? its harder to compress oil with a scroll.
Replace drier.
If all else fails and excessive oil shows in return gas drill a hole in lowest point of evap coil and blow it out.
Or replace E-coil.
Then again I dont know much, its just a quess.
 

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Snapdaddy

There are a lot of things to check, is the txv bulb at a 11 or 2 oclock position, too much air flow. and making sure the sub cooling is correct. You cant check super heat correctly with a txv. Are the refrigeration lines the right size and length?You shouldnt have a restriction, that would cause your suction pressure to be low. Txv could be over feeding.
 
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