[bobw]

Hi all,

Hope someone can give me some help here. I'll give you what I've found and a question or two at the end.

Bought this fridge used about 4 months ago. No idea how old it actually is. Getting conflicting views on the possible source of problem.

The fridge has been gradually losing cold over the last couple weeks. The ability to freeze is gone now -- running about 33-34 degrees so nothing frozen. Obviously the fridge portion is only cool now, running in the 40's. Holding there now for the last several days.

Compressor is running constantly but where I thought it'd be scorching hot, it's hot but can leave my hand on it comfortably. Only time it stops is for defrost cycle which goes for around 30 minutes or so.

The evaporator coils in freezer usually have about 2/3's covered with frost -- I've seen it written that this is the way it should be and, alternately, have been told it's bad.....?! As far I as I know the frost goes away during the defrost cycle but I'll have to verify that if that matters.

All fans interior and exterior are running, all vents seem to be moving air, coils under fridge are not particularly covered with dust and crud, switches for lights do turn them on and off, door seals are good.

The temp switch in the freezer works but doesn't seem to change anything (except off setting) but given the temp in there, it's not surprising. Even the lowest setting should be higher than 34 degrees I'd think. I tested it per Acme How To.com and it tests out as ok.

I tested the defrost heater and thermo unit:

According to Acme, the heater should read somewhere between zero and infinity, whatever your spec is -- spec sheet I have for this fridge says it should be 29 + or - 5%. My reading showed 0 on the 1K setting.

Thermostat unit "should display a reading of zero when the thermostat is cold and a reading of infinity when it is warm (40 to 90 degrees F depending on the model)." My reading was about 60 on the 1K setting, warm or cold.

It's been indicated it's a sealed system leak but I've read other things that say it could be something else. So I'm looking for a more definitive way of finding out.

Had a technician from the place we bought it come and without doing anything except look under the fridge, put a temp gauge in the freezer to verify the temp (20 degrees at that time) and listen to me when I told about the frost on the evaporator fins, but he didn't pull the panel to look for himself and didn't test anything else. He then proceeded to say it was a system leak, charge problem, oil problem, etc, and too expensive to fix. May be true but I want to verify.

Questions: Is it possible that the Defrost Thermostat could cause these kinds of symptoms? Or some other component I don't know about or haven't tested? Or should I just call it a day or look for another fridge (if it's a sealed system I'm not going there).

Any help or advice would be highly appreciated. Thanks.

BW

[woodchuck]

You do need to see if it is melting all the ice on the evaporator when it goes into defrost by removing the the inside back panel.

If the ice remains, it's a defrost problem. Otherwise it's the low freon based on your descriptions of the ice pattern.

[denman]

Here is the parts breakdown
BX21TW Parts List

Check to make sure both the evap and condenser fans are running during cool mode.

If the coils just have a light coating of frost and the unit will not cool then it is probably a low freon problem.
But if they are iced up then defrost is the probable cause

Remove the evaporator cover and check it out
You say the unit goes into a defrost cycle so the timer motor is OK but this does not ensure that the timer's contacts are closing.

The defrost thermostat could cause a defrost problem, it should be 0 ohms when frozen and open at room temp.

The 0 ohms on a 1 K setting for the heater seems strange but this may just be the meter's sensitivity. Best to measure it using a lower scale. You have continuity so it is probably OK, never seen one short they burn out (open).

You can force the unit into a defrost by turning the cam on the timer with a screw driver or a dime. Then just check to see if the heater gets hot. Don't burn your fingers they get very hot.

Here is a good site with fridge repair info
Refrigeration Help Section, Fridges, refrigerators, not cold enough, frost free problems and how to test, noisy fan motors, clicking on and off compressors, door gaskets

[bobw]

Thanks for the info WC. It just completed the defrost cycle and interesting enough, it didn't defrost the frost. Still has was was there when it went into the cycle. So now I'm wondering, would it be because of the thermo, heater, timer, one or more, all of them...? Any further things for me to check?

Hell, maybe it's all gone bad and the freon is gone, the compressor is shot, etc, in which case I'd hate to waste money on defrost parts. But getting a new fridge at this point could be as much hassle.

Just looked at the frost: As I said, there's light frost on about 2/3's of the evaporator fins mostly on the upper portion. There's two tubes the come out of the right side of the evap unit at the top -- the front one, which the defrost thermo clips onto, is frost free while the back one is covered with frost. Thought I'd just pass that along in case it means anything.

Other tips on what to check would be great. Thanks.

BW

[bobw]

Thanks for the info denman. Yes, I noted the defrost heater must have gotten hot at one point because there had been a piece of heavy paper jammed under the back panel by someone before we got it. Didn't see it till I yanked the panel. It was charred from the heat. Nice.

When the panel is on it vibrates and sounds like an airplane. No tightening will relieve it. The bottom middle floats as there are no screws there so that was the "fix". With the panel off it's all pretty quiet. I did notice that the compressor seems to have slop where the feet tighten -- the grommets look fine but it seems as if the thing oughta be tightened more, about a quarter inch of slop. Maybe it would stop the vibe.

Anyway, I've touched the defrost heater before while in defrost mode thinking it would be hot. Not so. I'll check that again. Also re-test. The 1K sens is the lowest I have on that meter for continuity I think, but will recheck that too.

Pretty sure the defrost thermo test was accurate but may just redo everything to be sure. If this all could actually be because of the defrost stuff, the lady of the house would be VERY happy as she really like the fridge. I'll get back on this stuff asap. Thanks.

BW

[bobw]

Forgot to mention:

RE"Check to make sure both the evap and condenser fans are running during cool mode." They do run, all the time except defrost cycle.

[bobw]

Okay, one hopefully not stupid thing: If I pull the freezer panel and have it off while the unit runs, then in the defrost cycle should it still de-frost the evap coils or am I skewing the test by having the panel of? I pulled it because of noise a couple days ago but just had the brilliant thought that maybe I was screwing up the testing of all this...........

[Icehouse]

Okay first. How did this person decide it was a sealed system problem without taking the back panel off ? psyhic.

Next the best way to test the heater is with voltage applied. I have seen too many pass the meter test (only battery voltage) only not to work when line voltage applied.

The frost pattern you described sounds like a sealed system, but without using gauges and an Amprobe you cannot tell for sure.

Try Whirlpool Service as they now own Amana.

[denman]

You can test it with the evap cover panel off.
You just want to be sure that the defrost thermostat is cold enough to be closed (0 ohms) But do not expect it to defrost properly, you are just checking to see if all components are OK.

During defrost the evap fan shuts off
Heater comes on
Heat builds up behind the panel in the coil area and melts the ice
The defrost thermostat opens cutting power to the heater when the ice has melted so the heater shuts off
The defrost timer keeps running till it moves to run mode and your fridge starts up again.

Most fridges will not run great with the evap cover off, the unit is designed so that the air flow is correct with the panel on and air flow patterns are critical.

[bobw]

Thanks for all the data guys. Couple more things before I call the junk man.

Re-tested the defrost thermo. I'd have to put it another freezer to test it cold, I think, since the temp only gets to about 34 in there. Nevertheless I tested it again and it still reads 60 on the 1k setting. Warmed it way up and reads the same.

Re-tested the heater and reads 0 on 1k. If I turn it to 10k it reads at about 25. I noted Icehouse said to test with line voltage on. Haven't done that yet as not sure where to do it yet and because of the following:

I'm not sure the heater is getting juice (or is dead) because it doesn't heat up in the least during the defrost cycle. Put fingers all over where I could get at it and not even warm at any time during the cycle. Since the thermo is in series with the heater, if the thermo is shot would that keep the heater from working at all?

Also, haven't checked the timer at all. It seems to time alright but could it be that it's not feeding the circuit during defrost mode?

One fellow told me to jam the evap fan for 10 minutes during cooling mode and if the evap coils didn't ice up it was the seled system. So instead of jamming it (for fear of burning out the motor) I pulled a wire so it wouldn't run. Replaced the back panel and now about a 1/2 hour later I've got frost forming all across the evap coil fins where I've never seen it before. Tempted to test it for a few hours and will if I think I can get away without screwing up the food supply, which is on thin ice anyway....sorry for that.

Any of this enlightening for anyone? Is there any component, capacitor or whatever, that would cause many things like this to go haywire at once? Or is that too much to hope for. I'm still hoping the sealed system is...sealed but maybe that's toast too.

I still see the defrost cycle doesn't get rid of the frost but that was with the back panel off. Next cycle I'll be sure it's on, then pull it to be sure nothing is actually happening.

BW