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View Full Version : Power to Light but fridge not running ..??



2tone
17-11-2007, 08:26 AM
Howdy ..

The defrost timer in our fridge was not working (running continuously and coils frosting over) .

We replaced the defrost timer with one from another fridge that was laying about the place . They both had 4 terminals so we checked the relays with the multimeter and matched up the terminals .

The fridge ran very well for about a week then it stopped cycling .
I got angry because i had spent quite a lot of time in accessing the defrost timer etc .. and was less than polite with it when i manually turned the defrost timer through its cycle to confirm it was working .

It seemed to be working alright but there was something strange about the way it was behaving . I was suspicious lets put it that way .

The defrost timer however returned to 100% duty cycle and i was annoyed . I was quite rough with it and actually banged it a couple of times in a caveman style of mechanics ..

Then soon after when i manually turned it through its cycle again there was an obvious short circuit .. a bright flash and an arcing sound to match .

I dropped the item out of plain surprise , and since then the compressor has be silent . The Light circuit still has power , but the compressor is silent .

Since it was an obvious short circuit we looked for a blown fuse , but there seems to be no std fuse in the fridges wiring ..

What is likely to have been blown from the short circuiting of the Defrost Timer that prevents the Compressor from operating , while the light circuit still has current .. ?

:confused::confused::confused:


pics , defrost timer .. short circuit aftermath , Circuit diagram ,

taz24
17-11-2007, 01:23 PM
Howdy ..


What is likely to have been blown from the short circuiting of the Defrost Timer that prevents the Compressor from operating , while the light circuit still has current .. ?

:confused::confused::confused:


pics , defrost timer .. short circuit aftermath , Circuit diagram ,

Looking at the wireing diagram I see no fuse in the supply to the comp. There is a thermal overload but I doubt it would be that.
I would look to the time clock the problem started there and you noticed the flash there.
It would seem to me that you have burnt the ends of the contacts and no power is passing through.

Look to the timer.

taz.

jack_lizhaoyang
17-11-2007, 05:08 PM
most likely is the timer itself spoiled.
by pass the timer see if the compressor can start.
make sure you unplug before doing so

2tone
17-11-2007, 05:38 PM
Yep we have done that .. hot wired the Defrost timer circuit , still the compressor is dead silent .

The defrost timer runs two circuits ,

1. the relay switch that switched between the normal cooling cycle and the defrost cycle .

2. the small motor that that times the switching of the relay


In the picture above of the Defrost timer wired up , the wire for the motor is the double Brown wire (you can see it is set apart from the others too)

The hot wire for the relay is the white wire

The cooling circuit for the relay is the Black wire connected to the White

And the defrost circuit is the Yellow wire connected to the White .

So we tested the circuit with White connected to black .. no go .


##########

Right now i will use the multi meter to test for continuity White- Black with the fridge plugged in ..

** back in two**

Yep .. with power on the White wire and the Black wire are in circuit .

2tone
17-11-2007, 05:41 PM
Next i will check for continuity between the Wite wire and the Yellow and the White wire and the Brown

white/yellow (defrost cycle) .. YES

White brown (motor for defrost timer) .. YES

So all the circuits seem to be operational

2tone
17-11-2007, 05:46 PM
Now i will hard wire the White wire to the Black wire and see if the Compressor is runs ..

White connected to Black .. No , the compressor does not run .

So even tho there is a circuit between the White wire and the Black wire the circuit is non-operational .


So where is the faulty item ??

2tone
17-11-2007, 06:05 PM
Now i will hard wire test the circuit for the defrost cycle ..


White to Yellow .. Blows the fuse on the fuseboard for the kitchen !!

2tone
17-11-2007, 06:08 PM
So there is a definite short circuit on the defrost cycle path ..

Now .. where is the short ??

And is the short circuit in the defrost path also preventing the Compressor from running ??

2tone
17-11-2007, 06:32 PM
I could really do with some advice here .. My frustration in trying to understand what is going on is dangerous .. having to pull the fridge apart again right now i snapped a terminal on the thermostat for the Freezer compartment .

Can someone please give advice !!

2tone
17-11-2007, 06:50 PM
Looking at the diagram .. the red path is live , when it is connected to the grey path there is a critical short circuit that blows the fuse at the household switchboard ..

So where can the short circuit be .. is it the Overload Relay that is shorting ?? seems strange to me that a overload reelay would short .. but what else could it be ??

2tone
17-11-2007, 07:01 PM
You have to understand that we have connected the wires from the Fridge to the new wires from the replacement Defrost timer .

Like this ..

2tone
17-11-2007, 07:04 PM
But the circuit diagram is clear Red connects to Grey
and there is a critical short circuit and the only thing on that path between it and the compressor is the overload relay ..

taz24
17-11-2007, 07:19 PM
Looking at the diagram .. the red path is live , when it is connected to the grey path there is a critical short circuit that blows the fuse at the household switchboard ..

So where can the short circuit be .. is it the Overload Relay that is shorting ?? seems strange to me that a overload reelay would short .. but what else could it be ??

you are makeing the situation worse.
Unless you can read a wiring diagram and test components then mayby you ought to leave it alone.

If you insist on going further you will continue to break things. You have already damaged the timer and now you have snapped a terminal.

taz.

2tone
17-11-2007, 07:34 PM
Yes what you say is true .. but you can read the wiring diagram correct?

So when the red wire is connected to the grey wire how is it possible there is a short circuit that trips the fuse at the switchboard .

I am asking for advice .. so how about you give some ..

I simply do not understand how there can be a short circuit on that connection .. it seems stupid to me that the overload relay can short circuit . I can understand it breaking the circuit .. but causing a short ? .. that seems illogical .

How about you give some constructive advice Taz ..

2tone
17-11-2007, 07:59 PM
oK .. moving forward

no surrender , Taz do you understand ?

The terminal that was broken was on the Thermostat for the Freezer compartment .. i guess i caused this as i say , but eitherway it was broken ..,


Looking at the terminal connector for this thermostat reveals something interesting .. (check the picture)

There is a distinct blue spot as if from an arcing on the casing of the connector - as if there was a short in the circuit there ..

This seems significant to me , so i hard wire the connector bypassing the Freezer compartment Thermostat and then bridge the Live wire of the Defrost timer to the feed for the Compressor ..

Now the compressor runs ..

2tone
17-11-2007, 08:04 PM
Interesting ..

taz24
17-11-2007, 08:16 PM
Yes what you say is true .. but you can read the wiring diagram correct?

So when the red wire is connected to the grey wire how is it possible there is a short circuit that trips the fuse at the switchboard .

I am asking for advice .. so how about you give some ..

I simply do not understand how there can be a short circuit on that connection .. it seems stupid to me that the overload relay can short circuit . I can understand it breaking the circuit .. but causing a short ? .. that seems illogical .

How about you give some constructive advice Taz ..

I can read the wiring diagram but the fact that you can't prooves my point that it may be dangerous for you to go further.
As for constructive advise I'm all for that but only if I thought it would help.
I'm sorry but I think for yours and others safety I think that you should seek and pay for professional help.

Not what you want to hear but my opinion.

taz

2tone
17-11-2007, 08:39 PM
.. it may be dangerous for you to go further...

Cheers taz .. but hey it could be dangerous to get out of bed too :)

Let alone the fact that it may well be dangerous to stay in bed



Does it matter which wire connects to what terminal on the Thermostat controller ?

We have a Brown Wire and a Red wire

The Thermostat controller has two terminals numbered 1 and 2 ..

Since Brown leads to Red in the circuit path it seems logical that

Brown .. #1
Red .. #2

jack_lizhaoyang
18-11-2007, 07:29 PM
2tone

you did not prove the compressor is short to earth.

most of time it is the compressor got problem.

take off power terminal on compressor (make marking!!!) check with your meter. none of the pin should go through to body. the ohm reading between each pin should be around 20-30
if you can prove the comp. is good directly supply power to it to test .

the overload relay can short to body when the metal pc is overheated. if this happen the comp. die already.

go ahead. be safty.


Plus.there is no difference for the wire connection on thermostst.

jack_lizhaoyang
18-11-2007, 07:51 PM
please take note there is one more path after the timer the compartment heater. usually we call it frame heater .
find the thrminal which marked (G) isolate it and test
good lucky

jack_lizhaoyang
20-11-2007, 04:34 PM
hi 2 tone
how is your fridge which got light but not cold?

Jack

jack_lizhaoyang
20-11-2007, 05:07 PM
Hi Jack again
I just read another post by you regarding defrost timer, here I'd like to share some of my knowledge on this topic.
For the domestic fridge
normally there are 4 terminals on this timer and 1 pin is far away from the other 3. among the 3 pins center one is common then 1 is long close contact for cooling 1 is short close for defrosting. the center pin together with the first pin( far away one) supply power to the driving motor.

besides difference of pin lay out different timer may working on different voltage and timing that is to say 1timer may cool for 6 hrs defrost for .5 hrs another may cool for 4 hrs defrost 15 minutes. So you can't anyhow replace it.It may work if you are lucky enough.

the difference of this type of timer and the solid state timer in your car, for me, is this one is used to control a longer time and it's cheaper.

timer itself is simply but in a real fridge it;s control get much more complicate, just read your fridge's wiring can you tell how the timer cut back from defrosting to cooling. this is a question i'm not quite sure about my though.
Jack

2tone
20-11-2007, 11:38 PM
Aloha Jack ..

My man , the fridge is running again .

Its getting Cold :)

Not certain that the thermostat is functioning correct , because i haven't heard it cycle off yet . But it is working and to be honest that is very good news .

I did use a defrost timer off a different unit , and so far so good . It is a solid defrost timer that i like the look of .

Connecting the terminals on the thermostat was quite simple .
Although one of the terminals had snapped it was a terminal that became narrow and had snapped at where the wide spade terminal became a more narrow spade .

The Wide spade was actually the same size as a standard terminal connector , and the same size as the terminals on the new defrost timer . So we used a piece of wire from the new timer and simply spliced it onto the existing wiring and the short length of the thermostat terminal remaining .25cm(+-) was enough for the connector to get a good solid hold .

Having said that the fridge was not cycling off i am very impressed to report that as i went to the fridge a minute ago after beginning to write this the fridge did right then cycle off .. it is very good news indeed Jack .

Surely the thermostat is working because now the compressor is not running , but if i turn the temp setting dial forward it starts up again . and back again - it shuts off .. good behaviour .

All in all a most satisfactory result , and we now much better understand the operation of the fridge .

What i have learnt most of all is that all defrost timers are not made the same .. that some of them are prone to mal-function .
The lightweight (cheap?) plastic ones especially seem likely to develop faults .


cheers .:cool::cool:

taz24
21-11-2007, 11:48 PM
Aloha Jack ..

My man , the fridge is running again .

Its getting Cold :)
cheers .:cool::cool:


I'm not sure if I should congratulate you or be gobsmacked at your ternacity.

I'll give you your due you don't give up and if what you say is correct then you seem to have solved the problem.
So well done and congratulations on repairing the thing.

Keep safe taz.