Heat pump frozen

Reply

  #1  
Old 02-19-18, 08:15 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
Heat pump frozen

My heat pump froze several times this winter. It seems it couldn't run defrost mode. It is about 10 yr old. I never paid attention to this issue before. Actually I never noticed whether it ran defrost mode before.
The wiring to the defrost board appears no problem. I even purchased a new board (S1-03101975102) to replace the original one (same model). It didn't help. There is a "test" jumper on the board. I tried to force to defrost mode but no response.
I was able to run the cooling mode to remove the ice on the heat pump, It took a few minutes but it worked. And, after the ice was removed, the heating mode worked very well. For me, this means all the hardware is functional. And I doubt this is caused by the low charge.
I went through a few check points according to a few websites. The fan worked well. Nothing blocks the outsider filter. No water drips on the unit. I also tried to remove the filter inside the blower. Nothing helped. Very frustrating.
Now I don't know what else I can do. I guess the inside thermostat shouldn't be the problem. Any suggestion?
 
Sponsored Links
  #2  
Old 02-19-18, 08:32 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 58,655
Received 1,050 Votes on 974 Posts
A model number of the heat pump would be a good start.
 
  #3  
Old 02-19-18, 08:36 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
Model # EABD-T036SB

- 13 SEER - 3PH
 
  #4  
Old 02-19-18, 09:12 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 58,655
Received 1,050 Votes on 974 Posts
I'm guessing yours is a single phase (1PH) if at a residence.

So far,,,, no usable service info located.
 
  #5  
Old 02-20-18, 09:06 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
Please see attached picture regarding the model info
 
Attached Images  
  #6  
Old 02-20-18, 09:21 AM
M
Member
Join Date: Jun 2016
Location: USA
Posts: 178
Received 3 Votes on 3 Posts
Different heat pumps have different ways of determining when to go into defrost. Some (older models) use mechanical timers in conjunction with a defrost thermostat. If the thermostat is cold enough and enough time goes by, the unit will go into the defrost mode, whether it's iced-up or not. When the thermostat heats up to a certain temperature, defrost is terminated. Hopefully, at this time, much of the frost has melted off.

Below is a list of possible causes.

Bad defrost control or timer
Bad defrost thermostat or sensor
Bad defrost relay
Sticking reversing valve
Bad reversing valve solenoid coil
Bad outdoor fan motor
Low refrigerant charge
Restriction
Outdoor coil blocked - possibly with leaves or snow drift
Unit sunk in ground - nowhere for ice to melt and drain off
Leaking gutter dripping water onto top of unit
Freezing rain - causes top of unit to freeze over - once this happens the rest of the unit will also freeze over
 
  #7  
Old 02-20-18, 10:33 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
That was the list I saw on a few websites. I checked most items and couldn't locate the problem. Below is my results for each item.

Originally Posted by Mad Scientist View Post
Different heat pumps have different ways of determining when to go into defrost. Some (older models) use mechanical timers in conjunction with a defrost thermostat. If the thermostat is cold enough and enough time goes by, the unit will go into the defrost mode, whether it's iced-up or not. When the thermostat heats up to a certain temperature, defrost is terminated. Hopefully, at this time, much of the frost has melted off.<br />
<br />
Below is a list of possible causes. <br />
<br />
Bad defrost control or timer<br /> defrost control board replaced
Bad defrost thermostat or sensor<br /> didn't check but the defrost control board test mode didn't work (under this test mode, it should bypass the sensor)
Bad defrost relay<br /> replaced
Sticking reversing valve<br /> Both cooling mode and heating mode can run. Does it mean no problem on the valve?
Bad reversing valve solenoid coil<br /> same as above...
Bad outdoor fan motor<br /> no problem
Low refrigerant charge<br /> Both cooling mode and heating mode can run. Does it mean no problem on the refrigerant charge?
Restriction<br /> no problem
Outdoor coil blocked - possibly with leaves or snow drift<br /> no problem
Unit sunk in ground - nowhere for ice to melt and drain off<br /> no problem
Leaking gutter dripping water onto top of unit<br /> no problem
Freezing rain - causes top of unit to freeze over - once this happens the rest of the unit will also freeze over no problem
 
  #8  
Old 02-20-18, 09:52 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 58,655
Received 1,050 Votes on 974 Posts
There is a "test" jumper on the board. I tried to force to defrost mode but no response.
That's a problem right there.
The next step would be to make sure the proper voltages were at the board. It sound like you may have been missing the 24vac (R) line.
 
  #9  
Old 02-21-18, 05:40 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
Originally Posted by PJmax View Post
That's a problem right there.
The next step would be to make sure the proper voltages were at the board. It sound like you may have been missing the 24vac (R) line.
Thanks! I will test it tonight. I never thought about this problem because both modes worked. All the wires go to the board. If the 24V R wire is lost, the heating/cooling mode can still work? Only the defrost mode can't be started? If that's the case, that could be the only reason... I will post an update later.
 
  #10  
Old 02-21-18, 03:29 PM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
I did the test. R wire is ok with 25V. Now what's the next step?
 
  #11  
Old 02-22-18, 10:55 AM
D
Member
Join Date: Dec 2012
Location: United States
Posts: 247
Received 1 Vote on 1 Post
See:
http://www.upgnet.com/PdfFileRedirec...001-B-0510.pdf

I'd check for reversing output in Test after making sure that all sensors are connected, and not afflicted with broken (=open) wires.

Also, here's a quote from the manual for my similar functioning board which may apply and might help (note especially the six second short needed):

...The control will initiate a defrost cycle every 6 hours (accumulated
compressor run time) to recirculate refrigerant lubricants.
This forced defrost timer will be reset and restarted following
the completion or termination of a defrost cycle.
The control will also initiate a defrost cycle when the TEST terminals
are shorted. This feature allows an installer or service
technician to start a defrost cycle immediately as required.
When the TEST terminals are shorted for more than six seconds
with a Y1 input energized and the high-pressure switch
closed, the ASCD will be bypassed and the compressor will be
energized. If an O signal is present, the control will not initiate a
defrost cycle. If the defrost cycle is initiated using the TEST terminals,
the control will bypass the normal auxiliary heat timings
and will energize the W1 Out and W2 Out terminals immediately
when it begins the defrost cycle.
When the TEST inputs are used to force a defrost cycle, the
control will ignore the state of the liquid line temperature. The
coil does not have to be cold for the heat pump to be forced into
a defrost cycle. After the TEST input jumper is removed, the
defrost mode will be terminated as normal. The defrost cycle
length timer will not be started until the TEST input is removed.
If the TEST terminals remain shorted, the control will keep the
unit in defrost mode.
...
 
  #12  
Old 02-22-18, 11:47 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
Thank you for the help. Could you clarify the following?
"When the TEST terminals are shorted for more than six seconds with a Y1 input energized and the high-pressure switch closed, the ASCD will be bypassed and the compressor will be energized. If an O signal is present, the control will not initiate a defrost cycle. "
During the test, how to keep the mentioned conditions, i.e. Y input energized, high pressure switch closed, and no O signal?
And I am still wondering, since the heating/cooling mode works, does it mean all these wirings are ok... For example, when I switch from heating to cooling, does it reverse the valve through the defrost control?
 
  #13  
Old 02-22-18, 05:44 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 58,655
Received 1,050 Votes on 974 Posts
Y input is present with a call for heat.
O is only present during a call for cooling.
High pressure closed is system normal. No high pressure shut down. Compressor won't run if that is open.

when I switch from heating to cooling, does it reverse the valve through the defrost control?
I was trying to locate the service info to find that out.
 
  #14  
Old 02-23-18, 05:32 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
Originally Posted by PJmax View Post
Y input is present with a call for heat.
O is only present during a call for cooling.
High pressure closed is system normal. No high pressure shut down. Compressor won't run if that is open.


I was trying to locate the service info to find that out.
Should I keep the unit running in heating mode to have Y energized? Last time when I did the test, I only keep the thermostat on heating mode, but the unit was not running... and I guess I don't need worry about O and high pressure. I will check O voltage anyway.
This morning the unit is frozen again. The outdoor temperature was about 32 degree F. The unit was running hard but the efficiency should be very low. I had to run cooling again for a while to remove the ice. I will run the test hopefully tomorrow if there is no rain.
 
  #15  
Old 02-23-18, 06:48 AM
D
Member
Join Date: Dec 2012
Location: United States
Posts: 247
Received 1 Vote on 1 Post
The essence of your problem is failure to defrost. I'd guess that this board is for demand defrost : which is supposed to mean defrost only when necessary. If so, read on...
The decision about whether a defrost is necessary depends on some measure of coil / liquid line temperature and ambient temperature. Chances are that there is a thermistor on the two COIL contacts and another thermistor on the two AMBient contacts. You can check these thermistors: remove leads, measure ohms across the two wires. The values vary with temperature and should probably be in the few thousand ohm area (probably 10,000 at 77F)
If the ambient thermistor is open (infinite resistance) the board probably will never initiate defrost because it thinks the ambient temperature is above 50F.
If the coil thermistor is open or in the wrong place or otherwise reading high it says things are warm enough so that a defrost isn't needed.
The defrost curve selection jumper decides which ambient / coil temperatures cause a defrost ... and selecting the wrong one could also mean that those defrost conditions are never met. This is the first thing you should check And make sure that if you change it you cycle the 24V power . If all else fails you can experiment with the different defrost curves - a time consuming exercise but what do have to lose.
 
  #16  
Old 02-23-18, 07:22 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
Originally Posted by dsomerv View Post
The essence of your problem is failure to defrost. I'd guess that this board is for demand defrost : which is supposed to mean defrost only when necessary. If so, read on...
The decision about whether a defrost is necessary depends on some measure of coil / liquid line temperature and ambient temperature. Chances are that there is a thermistor on the two COIL contacts and another thermistor on the two AMBient contacts. You can check these thermistors: remove leads, measure ohms across the two wires. The values vary with temperature and should probably be in the few thousand ohm area (probably 10,000 at 77F)
If the ambient thermistor is open (infinite resistance) the board probably will never initiate defrost because it thinks the ambient temperature is above 50F.
If the coil thermistor is open or in the wrong place or otherwise reading high it says things are warm enough so that a defrost isn't needed.
The defrost curve selection jumper decides which ambient / coil temperatures cause a defrost ... and selecting the wrong one could also mean that those defrost conditions are never met. This is the first thing you should check And make sure that if you change it you cycle the 24V power . If all else fails you can experiment with the different defrost curves - a time consuming exercise but what do have to lose.
I totally agree with you. When I was reading your reply, I thought about my entire troubleshooting process again. I guess I made some mistake and I will verify soon. If the defrost test mode requires the unit is running (Y input energized?), my previous test could be wrong. The defrost board may be working properly. Then the possibility could be the ambient thermistor as you mentioned. I didn't tested it because the test mode test failed.
I am quite sure the defrost curve jumper is in the right place. The manufacturer put the reminder in the box about this jumper and I set it up accordingly.
 
  #17  
Old 02-24-18, 07:07 AM
D
Member
Join Date: Dec 2012
Location: United States
Posts: 247
Received 1 Vote on 1 Post
If you try test mode, make sure you know how to shut the unit down immediately if the unit fails to leave defrost mode - e.g. disconnect near the unit.
If possible you should also observe the positions of the two thermistors ... lest they've fallen off.
Trying different defrost curves is a last resort but not without its successes - especially as the defrost board software is revised for different models.
Chances do seem good that the defrost board is ok...
 
  #18  
Old 02-25-18, 02:56 PM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
I did another test just now right before the rain came back. During the test the outdoor temperature was about 40 degree F. The result still confused me.
1) I kept the unit running heating mode. Then I shorted the test pins. After about 6 seconds, the fan stopped and the compressor was still running. The reverse valve should also work. It looked like the unit entered the defrost mode. Note I kept the pins shorted during this time.
2) I removed the screw driver and the test pins were no longer shorted. I thought the defrost mode should remain according to some curve. But the unit got back to heating mode right away.
3) The defrost curve select jumper was set according to the original board. It was on position "1". I always assume the original setting was correct. But I start to suspect that ... I changed the jumper to position "2" and tested again.
4) With the new setting, I shorted the test pins. It went to defrost mode again. However once the pins were no longer shorted, the entire unit turned off. I was a little nervous thinking something might be burned. After about 30 seconds, the unit started by itself but into heating mode. Then I realized that it was doing something according to curve "2", i.e. the compressor need be shut down for 30 seconds to exit defrost mode.
5) I checked the ambient temp thermistor. It was in good shape. And it returned some resistance reading. I may do further ice bath test if necessary. I couldn't locate the coil thermistor because I need open another case plate to get the access.
My confusion included:
1) It was successful to force the unit to defrost mode by shorting the test pins. However the defrost mode couldn't keep once the pins were not shorted. Obviously shorting the pins forced the board to defrost mode. Once the pins were no longer shorted, does the thermistor take effect? Because it was warm, its input might force the board to exit defrost mode? I don't know the mechanism behind. Could anybody help?
2) The heat pump was purchased by the previous owner. It was there for about 10 years. I simply trust the wiring was correct and I copied the original setting when I replaced the defrost board. However I noticed that at least two wires (FAN and COND) were obviously wrong on the board. Since the FAN is output and COND is input. I really doubt the unit ever entered defrost mode before. I swapped them now. The defrost curve jumper was on position "1". Now I am not sure whether it should be there. I tried to check the diagram (in dsomerv's post) but couldn't find my model. It appears either curve ("1" or "2") may work but I do want to pick the best one.
3) If the thermistor takes effect during test mode, I may need another test in a cold day. If it still shows the same result (exit defrost mode when the pins are not shorted), it means 100% the thermistor problem, right?
Help please. Thanks!
 
  #19  
Old 02-26-18, 07:10 AM
D
Member
Join Date: Dec 2012
Location: United States
Posts: 247
Received 1 Vote on 1 Post
1) is this what your hp looks like : http://www.upgnet.com/PdfFileRedirec...001-F-0409.pdf ?
if so....
2) Did you measure the resistance across coil-coilg wires ?
3) do the coil wires go to a thermistor clipped to the liquid line behind the panel (item 27) below the board compartment ?
4) is there a thermistor securely clipped to the liquid line as shown where item 8 on the parts explosion - 1) above ? If not, what's there ?

while the panel is removed, scrutinize the TXV (item 28) and attachments for things apparently out of place or disconnected.

Your experiments with the test jumper seem to say that the defrost is workable ... I don't know if it should remain in defrost when the test jump is removed it sort of makes sense that it doesn't. The 30 second delay seems to be what's advertised for jumper position 2.

Chances are the thermistors are 10k ohms at 25C type -- typical ohms vs temperature tables are easily found on line, e.g. http://www.legacychillers.com/cms_da...stor_10K-3.pdf
 
  #20  
Old 02-26-18, 09:21 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
1)Yes, the model EABD-F036SB is on the list. What do you think about the defrost curve setting? Should it be on position "1"

2) I didn't measure the coil-coilg wires. I will do it next time. I only measured the ambient temp wires and the reading was 22.2k. When I compared with your 10k ohms chart. It actually matched, which was a sign that this thermistor could be ok.

3) I couldn't see it without opening the panel. Will do it.

I don't remember where came the impression that, after the test jumper is shorted, the unit will keep on defrost mode for about 1 minute according to the selected defrost curve. Maybe some youtube video. But the test in the video could be done in a cold day... I agree that it make sense if it doesn't - kind of self protection. And if it doesn't, I am more confident the board is ok and the root cause is the thermistor. Most likely the one on the coil.

So I am planning my next test:
1) measure the coil sensor wires .
SENSOR LIQUID LINE. Is it also 10k ohm thermistor?
2) open the panel to access the sensor and see whether it's detached.
3) check other wirings around TXV.

I can do these inspection this week. However the weather becomes warm suddenly. I kind of hope it becomes cold again for another test.
 

Last edited by PJmax; 02-27-18 at 10:12 AM. Reason: removed formatting
  #21  
Old 02-27-18, 06:54 AM
D
Member
Join Date: Dec 2012
Location: United States
Posts: 247
Received 1 Vote on 1 Post
1) also check that the ambient thermistor is properly located lest it be sitting somewhere that's always warm
2) I had my thinking exactly backwards when I said, somewhere above, that an open thermistor would indicate high temperature - as you can see from the thermistor table, high resistance = low temperature ... so a short (or abnormally low ohms) is what would falsely indicate highest temperatures that could inhibit defrosting...
3) When you visit the coil-coilg thermostat, read its part number if possible, just in case a bogus part has been installed somehow.
 
  #22  
Old 02-27-18, 07:27 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
I haven't got a chance to check. May do it tonight or tomorrow. I will check the part number carefully. Thanks for the reminder.
The ambient temp sensor seems to be mounted ok. See attached picture (I marked it in red circle). Is it the normal place for it?
About thermistor design, I saw PTC (resistance increases as temperature rises) and NTC (resistance decreases as temperature rises). I guess heat pump use NTC. I hope I could find a large resistance to run a test...
I found an announcement from YORK in 2006 regarding the defrost curve select jumper. Position "1" is the only choice for seer 13 unit. So the existing setting should be right.
 
Attached Images  
  #23  
Old 02-27-18, 10:14 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 58,655
Received 1,050 Votes on 974 Posts
That location is fine. It needs to read true outdoor temperature with no influence from the condensor.
 
  #24  
Old 02-27-18, 03:54 PM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
I measured the two thermistors just now. The outdoor temperature was about 52 degree F. The ambient temp sensor read about 18k ohm. It matched the chart well. The unit was not running for a while. The coil temp sensor read about 3k ohm. If it's the same type of thermistor (10k-3), it was way too low. So far it appears that the problem is the coil thermistor.
When I tried to remove the front plate to access the coil thermistor, I got some problem. There is a port on the front plate. I can see a pipe attached to the back of the plate. See the attachment. What is this port and pipe? Can I detach it temporarily? Any suggestion how to remove this front plate? I never opened this plate before and I don't want to damage the pipe.
 
Attached Images    
  #25  
Old 02-28-18, 07:16 AM
D
Member
Join Date: Dec 2012
Location: United States
Posts: 247
Received 1 Vote on 1 Post
If the coil thermistor S1-03101276000 is indeed a 10k (which I'd bet) the 3k ohm reading would sure explain the problem ... and a replacement seems inexpensive enough, e.g. https://www.repairclinic.com/PartDet...276000/2339083

SInce you had access to take the backside picture maybe the coil thermistor is accessible without removing the plate ? - I think its on the pair of blue wires ?

I don't know what the green wire is ... where does it attach ?

The tube and fitting that seems to prevent plate removal may be for refrigerant monitoring - maybe removing the cap would allow the plate to slide over the hole or the tubing is flexible enough to be moved attached - but I'm sure that PJmax will know better than I.
 
  #26  
Old 02-28-18, 07:54 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
I will replace this coil thermistor and hopefully this is the only problem.Yes the blue wires are for the sensor. The sensor is clamped well on a tube. I can see it but can't reach it.
The picture was taken from the top through the fan grid. I can remove the fan but it's still hard to access the sensor from the top, unless I jump into the unit. The sensor is quite low near the ground level.
The green wire should be for grounding going to the defrost board case. From the front, I saw a screw below the black cap. I am guessing, if I remove the screw, the tube behind may be detached. I may have to remove the black cap since it appears bigger than the hole. But I don't know whether the cap can be removed. This port is displayed on the drawing but there is no part number marked.
As you suggested, the other option is to partially remove the plate. Keep the tube attached but partially open the left side. Is the tube flexible enough to allow the plate turn about 30 degree?
 
  #27  
Old 02-28-18, 10:04 AM
D
Member
Join Date: Dec 2012
Location: United States
Posts: 247
Received 1 Vote on 1 Post
You'd think that the panel is made to be removed - if not, why the mounting screws? - and it covers important parts needing service eventually ...

The tubing doesn't appear to have much "loose" length so maybe it'd be tricky to move the panel though it looks like you wouldn't need to move it very far ...
 
  #28  
Old 02-28-18, 10:44 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
I would have done it yesterday if there is not such a black cap. I agree that the screw is there to be removed. However I am afraid of the cap. Is it some port for pressure measurement? My impression is that to detach the tube first is the right way to remove this plate, because as you said the tube inside looks not very long.
It is weird for me they put it on the drawing but didn't identify what it is...
http://www.upgnet.com/PdfFileRedirec...001-F-0409.pdf
 
  #29  
Old 03-01-18, 05:40 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
I have ordered the coil thermistor online yesterday. Once it arrives, I will replace it and see how it works. I did some research last night. The cap is a seal cap for the schrader valve. Although I still don't know the purpose of this valve, the cap should be ok to be removed temporarily (if the valve is not leaking). Any additional suggestion, please let me know. Thanks!
 
  #30  
Old 03-01-18, 07:02 AM
D
Member
Join Date: Dec 2012
Location: United States
Posts: 247
Received 1 Vote on 1 Post
Sounds right to me ... proceed firmly but gently ;-)

Pages 6,7 of this: http://www.upgnet.com/PdfFileRedirec...001-A-0204.pdf describe the defrost operation for a different York board but I think their strategy for demand defrost applies to most (all) of their heat pumps; so it may be useful/interesting to peruse.
 
  #31  
Old 03-01-18, 08:51 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
Very useful. If I read it earlier, I may draw a conclusion based on this:

"The control will terminate the defrost cycle immediately after the liquid line temperature reaches 80F or after eight minutes of defrost operation."
 
  #32  
Old 03-04-18, 01:49 PM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
A quick update. I have replaced the coil thermistor. I did a forced defrost. When I remove the screwdriver from the test pins, the defrost mode continued. I guess it followed the selected defrost curve. I didn't see any automatic defrost process. However I didn't see any ice on the unit this morning. The temperature was slightly above 32 degree but it was cold in early morning. It appears I have fixed the problem. I will keep watching.
Thank you dsomerv and Pjmax for the great help!
 
  #33  
Old 03-05-18, 10:47 AM
D
Member
Join Date: Dec 2012
Location: United States
Posts: 247
Received 1 Vote on 1 Post
Well done !
Out of curiosity:
- how was the panel removal experience ?
- were there any clues about how the thermistor failed ?
 
  #34  
Old 03-05-18, 05:46 PM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
I didnít remove the panel completely. First I remove that black cap and the screw below. The tube was detached from the plate. When I tried to remove the panel, I noticed I had to remove the wires from the thermostat. Thatíll be a lot of work. Eventually I decided to keep the panel and the defrost board compartment bonded, but detach the top of the compartment from the unit. In this way I can partially open the panel and access the thermistor.
I did the measurement before I removed the sensor. It returned some different value but still too low. Both the sensor and wires look intact.
So far the unit is working properly. No ice is observed since then.
 
  #35  
Old 03-06-18, 05:52 AM
J
Member
Thread Starter
Join Date: Feb 2018
Location: USA
Posts: 20
Received 0 Votes on 0 Posts
This morning was cold (25 degree) and I saw ice built up inside the unit. I started to worry about that the problem came back. Then I was happy to see the defrost mode started by itself. In about 1 minute the ice was gone and the unit went back to heating mode. Now I know the fix is successful.
 
  #36  
Old 03-07-18, 05:34 AM
D
Member
Join Date: Dec 2012
Location: United States
Posts: 247
Received 1 Vote on 1 Post
sweet ... .
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: