Fan not working on Engel SR70F

Submitted: Tuesday, Jan 14, 2020 at 00:52
ThreadID: 139554 Views:718 Replies:5 FollowUps:10
Recently my upright 57L Engel fridge started to cycle more and more. It turns out the fan that pushes air over the condenser is not working.
I have tested the fan (24v dc) and it works fine. There is no voltage output at the connector where the fan plugs in.
Anyone have a wiring diagram? Google isn’t helping me.
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Reply By: ctaplin - Tuesday, Jan 14, 2020 at 02:13

Tuesday, Jan 14, 2020 at 02:13
Hi Nick, try putting your multimeter on AC and check the voltage at the connector where the fan plugs in.

The compressor and fan run from AC power on all Engel fridges as the 12 volt DC is converted to AC power to run the compressor that is really just a solenoid device that goes up and down according to the frequency of the AC waveform.
Then you can buy a replacement 24 volt AC fan at Jaycar. I have the 80 litre upright Engel fridge/freezer and ended up completely rewiring it and fitting lots of small fans to make it perform up North. It was next to useless when it was new, now it can cool stuff down like the best of them because it has fan forced cooling within the cabinet that circulates cold air from the evaporator.

Cheers,
Chris
AnswerID: 629516

Follow Up By: RMD - Tuesday, Jan 14, 2020 at 08:51

Tuesday, Jan 14, 2020 at 08:51
Chris
Isn't that "circulates cooler air over the condenser?" which is what fitting of fans usually does and is his problem! Yes you can add internal cool flow fans from the evaporator too but it is already a fridge to do that. Just a bit confused with the meaning there.

Nick.
Seeing the fan power is effectively AC, you can use DC fans, I use two in series for quietness and they run on half voltage and move a lot of air past the condenser. My 40 L Engel WILL now freeze to -18, in 30 C ambient, something it never did before in it's life before the fans. The DC fan/s is used via a rectifier diode pack to make the AC from the Engel inverter to DC for DC fans.
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Follow Up By: nickb - Wednesday, Jan 15, 2020 at 01:10

Wednesday, Jan 15, 2020 at 01:10
Cheers. The existing fan is definitely 24V DC according to its label. The fan works perfectly when I put voltage directly to it. I did check again for AC or DC output, only getting 1V AC, 0V DC.

If I can’t find out why there is no output on the fan terminals I think I will just grab a 12V fan and connect it to the compressor wiring. Hopefully the extra 0.1A load doesn’t upset it!
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Follow Up By: Allan B (Sunshine Coast) - Wednesday, Jan 15, 2020 at 11:30

Wednesday, Jan 15, 2020 at 11:30
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Hi Nick,

Was the compressor motor actually running when you looked for output on the fan terminals?
On some Engels this DC output is derived from the motor AC current and will not be created unless there is motor current actually flowing.

Cheers
Allan

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Follow Up By: Allan B (Sunshine Coast) - Wednesday, Jan 15, 2020 at 12:19

Wednesday, Jan 15, 2020 at 12:19
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Nick, in an Engel, there can be problems with connecting a fan to a 12vdc point that becomes 'live' when the fridge runs. If so there are alternatives.

1) Use your existing 24vdc fan connected to the motor ac input via a bridge rectifier, Jaycar ZR1304. You would need to check the ac voltage to the motor and maybe employ a voltage-dropping resistor if necessary.

2) use a 12vdc fan controlled by a thermostatic switch: Jaycar ST3831, 50c, normally open, $5.75, positioned near the compressor/condenser.
Cheers
Allan

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Reply By: RMD - Wednesday, Jan 15, 2020 at 13:00

Wednesday, Jan 15, 2020 at 13:00
You probably can't have a 12v DC fan running off the compressor wiring which is above 22v AC. The fan even if rectified will try and spin at very high revs. If the OE fan was/is connected to Compressor wires then is will be an AC fan, unless it has a rectifier in line somewhere to that exit plug.
Seeing the fan does say it is 24v DC, it seems to be rectified somewhere on the board before hand. Have you looked at the board to see and component failures or loose or cracked terminals? The connection of DC fans with suitable small rectifier can be done with two 12v dc fans in series and their power source run from the AC which directly feed the compressor. 0.1 amp is how my 40 litre feeds the two 12dc fans it runs. I fitted them to mine long before Engel discovered the fitting of fans. It is needed because, used as freezer, it would hardly keep frozen in 30 degree.
AnswerID: 629533

Follow Up By: Allan B (Sunshine Coast) - Wednesday, Jan 15, 2020 at 14:22

Wednesday, Jan 15, 2020 at 14:22
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Hi RMD, Engel do some unorthodox things in their circuitry and some, if not all, of their units produce a square half-wave dc then pass it to the 'motor' via a capacitor to create full-wave ac. The fan is connected across the capacitor which provides a nominal 24vdc. There is no conventional rectification to supply the fan. I am never comfortable with such circuits even if they do work.
If his 'compressor motor' is running and his fan runs on test then the capacitor I referred to must be intact so maybe his model uses a rectifier instead and it is faulty. Who knows? It is very hard to get technical info on Engels.

There can be a problem sometimes with placing 12v brushless computer fans in series. Not always maybe, but sometimes. Each fan relies upon its current to flow through the other fan and as they operate by 'chopping' the dc the current path is not contiguous which causes upsets. They can get very confused! Note that this may not apply to all 'computer' fans but I have encountered it twice. Wondered what was happening when each fan would rapidly get a burst of power then coast in turn.
Nick may do better to use his existing 24vdc fan connected to the Engel 'motor' via a bridge rectifier but as I said above, he may need to trim the fan voltage.


My own Waeco has been retrofitted with two fans but not in series.
Cheers
Allan

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Reply By: nickb - Thursday, Jan 16, 2020 at 02:09

Thursday, Jan 16, 2020 at 02:09
Yes, my back up plan was to run the fan independent of the control board., thermally controlled.

The compressor was running when I did my tests. I wasn’t sure if the fan ran with the compressor or had it’s own control/thermocouple. The compressor runs at about 13V AC I think, I will confirm when I’m next in the shed. I’ll also take a pic which may help.

I can’t see any obvious physical issues with the pcb but I can’t get it out to check the underside without breaking some clips.

AnswerID: 629542

Reply By: Allan B (Sunshine Coast) - Thursday, Jan 16, 2020 at 09:38

Thursday, Jan 16, 2020 at 09:38
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Nick, I am attaching Engel Block & Wiring diagrams which may be of use to you.
They are for the 'F' Series which I had. Yours may not be the same.
Click on the images to 'open' them for more clarity.
Sorry that I now can't find my images of the internal circuit boards. It was years ago and I had to reverse-engineer them to draw them. They went with the old Microsoft PC I guess.


Cheers
Allan

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Follow Up By: nickb - Friday, Jan 17, 2020 at 00:24

Friday, Jan 17, 2020 at 00:24
Great stuff, hopefully helps me out! Thanks!!!
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Reply By: nickb - Friday, Jan 17, 2020 at 00:26

Friday, Jan 17, 2020 at 00:26
Some pics that may be useful:







AnswerID: 629550

Follow Up By: RMD - Friday, Jan 17, 2020 at 14:04

Friday, Jan 17, 2020 at 14:04
Nick
The fan seems to be positioned so it blows air over the compressor and perhaps some swirl gets to the condenser. Lovely to cool the compressor, but I imagined Engel would have provided a definite positive directed airflow in to fan and out to internals system, not a perhaps airflow. Although different, my40 L Engel had no fans OE, and I fitted two 12c dc 100mm fans wired in parallel on one side and a larger 100mm 12Dc fan extracting fan wired in series with those two on the other side of the cabinet, effectively extracting all air from the two smaller fans. The large one passes around the same current as the two in parallel so a match of current flow. All works on rectified AC about, 120ma in total, which runs the compressor. Because they all run below normal full voltage they are not much different to the solenoid compressor noise. In fact it breaks it up a bit. ie, white noise. A switch on the supply to the rectifier enables the fans to be switched off if required. Not as important in cold weather to need a fan though.
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Follow Up By: nickb - Friday, Jan 17, 2020 at 20:13

Friday, Jan 17, 2020 at 20:13
This fridge is designed to be in an enclosure without vents. The front of the fridge has an “inlet” vent at the bottom and an “outlet” vent at the top, the fan then just Cirvulstes it as required. Looks like the position of the fan is more to do with keeping the fridge compact. It definitely made a difference as the compressor has been running much longer lately.

I have the same fridge but slightly older version, it has no front vents or fan. I assume it was designed to go into a vented cupboard or similar.
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Follow Up By: Allan B (Sunshine Coast) - Friday, Jan 17, 2020 at 20:37

Friday, Jan 17, 2020 at 20:37
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"Cirvulstes"?
I had an uncle that caught that. Very painful I believe. lol
Cheers
Allan

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Follow Up By: nickb - Saturday, Jan 18, 2020 at 02:02

Saturday, Jan 18, 2020 at 02:02
Yes, very painful in the groin area!!!!

My fat fingers were supposed to write circulates...
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FollowupID: 904557

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