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domwild
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Joined: 16/12/2005
Location: Australia
Posts: 873

Posted: 12:35pm 20 Sep 2013

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Hi,

My F&P fridge stopped the other day, checked the compressor electrically and worked out the thermostat is open continuously. When disconnecting the wires I did not make good notes which colours go where and also found one wire to a heater behind the fridge evaporator had burned through. Lucky it did not touch any metal.

There is no timer to the coil heater (defrosting) and there is no fan. The thermostat has four poles, two earth and the on/off poles for the compressor.

The only other switch is the light on/off switch.

Question: Fridge now runs OK but the fridge evaporator ices up, no surprise. As I can no longer see how the heater was hooked up I am wondering when the heater comes on.

Is it on all the time when the compressor is running?? Heating and cooling? Hardly!

Is it on when the fridge door is open and the light comes on? Short time for the heating cycle only. The contacts of the light switch show signs of arcing, which a small fridge lamp would not have caused, so would I be right in assuming the heater is connected to the light switch? In parallel, light and heater comes on??

Thanks.

Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill

domwild
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Joined: 16/12/2005
Location: Australia
Posts: 873

Posted: 01:04pm 28 Sep 2013

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Have worked out a system to defrost the evaporator coil in the fridge compartment: Set a timer switch to switch the fridge off at 4AM for a certain time to make sure the compressor is off and the fridge defrosts.

Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill

Tinker

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Joined: 07/11/2007
Location: Australia
Posts: 1904

Posted: 03:47am 29 Sep 2013

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FWIW, The old fridge I converted to my efficient chest fridge had the heater coil connected to the start relay thingie at the compressor terminals so that:
When the compressor ran the heater was off.
When the compressor was off the heater was on.

Klaus

domwild
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Joined: 16/12/2005
Location: Australia
Posts: 873

Posted: 12:01pm 29 Sep 2013

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Thanks for that, Klaus. Must have a look at the wiring.

Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill

domwild
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Joined: 16/12/2005
Location: Australia
Posts: 873

Posted: 01:26pm 30 Sep 2013

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The start "relay thingy" at the compressor switches from the start wiring in the compressor to the run wiring. How that works in switching the heater on/off I cannot understand.

If the thermostat can switch between heater on/compressor off and vice versa, then I can understand your scheme. Old age is a terrible thing, try to avoid it!

Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill

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