Refrigerator problem: Insufficient cooling

question: failing compressor or plugged drier?
Kenmore model 106.77292 top freezer, almost 12 years old, R134a system, diagnostics so far:
1. lowest refrigerator temp about 50 degrees F 2. lowest freezer temp 26 degrees F, also is temp at evaporator inlet (after capillary tube) 3. temp of line at compressor suction inlet 84 degrees F 4. temp of line at compressor outlet 109 degrees F 5. defrost heater good at 33 ohms, evap coils NOT iced up 6. defrost thermostat working properly 7. defrost timer working is working properly 8. evap fan and condenser fan both working properly 9. compressor runs fine, but is noisy on startup for about 30 seconds, has been this way 16 months 10. simple test to suggest not low on R134a: unplugged refrigerator from wall socket, plugged back in, took 3 cycles of thermal overload protector for compressor to restart, suggesting there is significant high pressure freon. 11. no visual evidence of leaks, i do NOT have a leak detector
anything else i could try?
for further diagnostics, i have one bullet line tap valve. would i get the best diagnostic usage by installing on compressor suction or outlet? (instructions are not clear if i should mount on copper or steel lines from compressor, i would prefer NOT to mount on copper line, to save them for later brazing)
last question: why do driers now come with a schrader valve fitting? can adequate liquid freon be injected after evacuation and with compressor NOT running? this system specs at 4.000 ounces of R134a.
btw, i have the new compressor and drier. was disappointed to learn that compressor has no oil in it, from the factory. this compressor needs 280 cc of ester oil.
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question: failing compressor or plugged drier?
CY: From what you write, neither.
Kenmore model 106.77292 top freezer, almost 12 years old, R134a system, diagnostics so far:
1. lowest refrigerator temp about 50 degrees F 2. lowest freezer temp 26 degrees F, also is temp at evaporator inlet (after capillary tube) 3. temp of line at compressor suction inlet 84 degrees F 4. temp of line at compressor outlet 109 degrees F
CY: That's a bit too cold, when running.
5. defrost heater good at 33 ohms, evap coils NOT iced up 6. defrost thermostat working properly 7. defrost timer working is working properly 8. evap fan and condenser fan both working properly
CY: Very good things to check.
9. compressor runs fine, but is noisy on startup for about 30 seconds, has been this way 16 months
CY: Well, it's near to the end of usable life.
10. simple test to suggest not low on R134a: unplugged refrigerator from wall socket, plugged back in, took 3 cycles of thermal overload protector for compressor to restart, suggesting there is significant high pressure freon.
CY: I doubt that's a valid test for high pressure freon level.
11. no visual evidence of leaks, i do NOT have a leak detector
anything else i could try?
CY: Four ounce charge won't leak enough to be worth detecting.
for further diagnostics, i have one bullet line tap valve. would i get the best diagnostic usage by installing on compressor suction or outlet? (instructions are not clear if i should mount on copper or steel lines from compressor, i would prefer NOT to mount on copper line, to save them for later brazing)
CY: I always mount a BPV on the low pressure side.
last question: why do driers now come with a schrader valve fitting? can adequate liquid freon be injected after evacuation and with compressor NOT running? this system specs at 4.000 ounces of R134a.
CY: So you can measure the running pressure on the high side.
btw, i have the new compressor and drier. was disappointed to learn that compressor has no oil in it, from the factory. this compressor needs 280 cc of ester oil.
CY: You may have to buy some ester oil, then.
CY: Did you want to ask any more questions? I've got a few guesses what is wrong, and how to treat it.
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yes, would like to get your input, thanks.

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Oh! Well, in that case.....
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Christopher A. Young
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I had my defrost timer broke in the ON position once,
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My guess is that your fridge is low on freon. Piercing valve on suction line, and read the suction pressure with the system running. Add refrigerant until the discharge temp comes up a bit, and the suction pressure comes up. Good idea to vacuum it out, and charge with a known weight of refrigerant. But, I've just topped em off by gages, and temperatures.
Yes, it's possible to inject liquid freon into the high side, after the system is vacuumed out.
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installed piercing valve on suction line, suction pressure 15 psig after fridge ran for 5 minutes, that sounds normal to me, does that sound normal to you?
afterward, i added 26 grams of R134a over 4 minutes, suction pressure now 20 psig; however the second loop (out of 10 loops) on the evap coil is still not frosted.
any input would be appreciated. thanks for your help.
failing compressor, plugged drier, plugged capillary???
---------------------------------------------------------------------------------------------------------------------- On May 23, 8:22pm, "Stormin Mormon"

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From what you were describing, I'd have thought the suction pressure was below atmospheric. 15PSI running suction is a bit too high, on a household refrigerator. I'm thinking at this point there is something badly wrong with the compressor. Sounds like it's not pumping refrigerant. Add some freon, and it's still not cooling.... that's a very strong hint that the compressor has problems.
Plugged drier or capillary would give you a very low suction pressure.
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thanks for your input, looks like it is time to dig out the ole brazing torch.
On May 26, 8:13am, "Stormin Mormon"

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removed old compressor from refrigerator, then cut the top of the compressor off, removed motor and pump. removed reed valve and found a lot of "black" microscopic particles under the seat, apparently "wear" particles from moving parts. the refrigeration oil was "cloudy" with these black particles. removed piston, it has no piston rings, so the problem was not caused by a "broken" ring. there was evidence that the reed valve was slapping the top of the piston; this may have been the "noise" on startup, which first appeared about 16 months ago.
possible reasons for this compressor to inadequately pump freon, was "wear" of moving parts and the presence of "wear" particles, which may have inteferred with the reed valve.
they don't make things as good as they did decades ago! so if your fridge/compressor is 12 years old, and you get insufficient cooling (after checking all other possibilities), consider replacing the fridge. the presence of "wear" particles would suggest that the freon lines (condenser, capillary tube (if your fridge has one), and evaporator coil) should be flushed, before installing a new compressor, this assumes that refrigerant oil travels with the liquid freon.
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