Fridge help - still !!

[Colin_374358138]

Hi All,

When 12s connected, car engine running and the fridge switched to 12v a relay switches in the distribution box under the sofa.

It doesn't switch a lot. Just sometimes. But it sounds like its mostly off. About once every 10 seconds there is an upbeat 'click-click' (presumably an on click) and then almost immediately a downbeat 'click' (presumably an off click).

I know its to do with the fridge cos when I turn the fridge to off it stops.

Should it do this ? I thought the fridge relay for 12v operation was in the car and after that the wires ran straight to the fridge.

I have put on a new 12s socket and plug. I have double checked their wiring. I have run the car at 3k rpm with a brick on the pedal. I have disconnected the van battery to make sure that the fridge is the only thing drawing current from the car. I have checked that the voltage across pin 6 (red) and 7 (black) is 14.2v so the cars alternator seems fine. The car has a relatively new battery and is at 12.8v (fully charged). The alternator can supply plenty of current to run AC and DVD players when it wants to....

So I think that foir some reason the fridge is not comming on when on 12v... or am I wrong and the relay switching is for something else or normal ?

C

 

[WatsonJohnG]

Hi Colin it sounds like the habitation relay that you are hearing

You probably have a Smartcom type of relay in the car boot (later ones are adjustable)and this reacts to voltage output from the car alternator to power the fridge circuit

The load from the fridge is causing a slight drop in voltage and so the Smartcom is switching off and you are hearing the habitation relay open and close

If you get someone to raise the car revs slightly all should be well

You can verify that it is the habitation relay by switching nna 12V interior light in the caravan .

As the habitation relay clicks on the light should go off and as it clicks off the light should go on

Hope that helps

 

[WatsonJohnG]

Hi Colin it sounds like the habitation relay that you are hearing

You probably have a Smartcom type of relay in the car boot (later ones are adjustable)and this reacts to voltage output from the car alternator to power the fridge circuit

The load from the fridge is causing a slight drop in voltage and so the Smartcom is switching off and you are hearing the habitation relay open and close

If you get someone to raise the car revs slightly all should be well

You can verify that it is the habitation relay by switching nna 12V interior light in the caravan .

As the habitation relay clicks on the light should go off and as it clicks off the light should go on

Hope that helps

nna =on an !!

 

[Colin_374358138]

Hmmmm don't know.

I can tell you that even at 3000 rpm with a brick on the accelerator pedal of the car the clicking is unchanged.

I have not tried a light on in the van - I'll try that yes.

I guess I really need to get a multi meter on the 12 lines as they enter the fridge to truly know if its getting juice or not. Is this an easy probe ? are the lines still black and red when they get there ? It says on the Bailey wiring diag that they are....

C

 

[Colin_374358138]

in fact on bailey wiring diag they are red and white - no matter.

 

[WatsonJohnG]

It could be either a faulty Smartcom or a faulty habitation relay if not the wiring!!

I would try after the light test taking the wiring direct to the fridge without the Smartcom and that will rule it in or out

I prefer the 4 pin relay because I have seen problems with the voltage sensing type before

 

[Colin_374358138]

Do you know I think its the car relay.

I probed the 12s socket with engine running. 14v no problemo.

Then I connected the 12s plug but took the back off it so I could probe the pins.

Immediatelt the volatage drops to 0v - rising occasionally to 14v for about 1 second in every 20.

So if I'm probing at this point (ie towbar) then it's surely the car voltage thats dropping out and turning off the fridge relay.......

Isn't it ? At this point the voltage would be 14v whatever the fridge relay is doing if everything were healthy at the car end.

So..... maybe the car relay is wanting / needing to charge the car batt..... or maybe its faulty....

My thinking head is defo not on right now. Does my logic follow ?

 

[Colin_374358138]

I've got a spare 110Ah Numax lying around the garage. I intend to wire this directly to fridge red n black 12 on van plug. If this can keep the fridge relay open I think it will conclusively proove that the van side is OK. Must therefore be the car.

Where's best place to get new Smartcom Relay ?

Col

 

[Colin_374358138]

Of course it could be the alternator........