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Plumberpro
Plumberpro, Home Appliance Technician
Category: Appliance
Satisfied Customers: 634
Experience:  Heating and hot water heating appliances experienced
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Danfoss FP975 code n33 and relays are dropping in and out

Resolved Question:

Danfoss FP975 coe n33 and relays are dropping in and out every second or so

Submitted: 2 years ago.
Category: Appliance
Expert:  Plumberpro replied 2 years ago.
Plumberpro :

. this means itvhasnt fully booted upmn. Turn the power to it (fused spur normally) then back on. If this doesn't work there is a reset button . small hole on front of it , you would need a something small and thin to push gentlybinto ,ie cocktail stick

Customer:

Ok completely switch off the AC supply, not sure where the spur feeder is so turned off the whole house secs, then turned back on then pressed the reset on th front of the panel

Customer:

System mreposnse was a follows

Customer:

Whilste Power was off - danfoss screen dead

Customer:

Whilst power on, danfoss shows ticking clock etc all looks normal

Customer:

after reset danfoss, shows n33 a sec, then screen returns to normal

Plumberpro :

That's great , is it back working?

Customer:

Well there in no fault now and the relays are not dropping in and out in auto mode, how ever that may be because we are out of a time set, CH and HW are timed off after 09***** will pop down and see what happens if they are set in (manual) ON mode, both that is

Customer:

No as follows- 1. Both CH + HW on manual ON, screen flash n33, then time. 2. Relays click in and out CH and HW, then back to 1, then about 1 sec then 2, then about a sec t1 etc.

Plumberpro :

To be honest , these programmers do eventually fail. When they do there are no repairable parts unless you are an electronics engineer. It may be time to replace

Customer:

OK, so to replace I will need a 2 channel unit that fits onto a MK9 or SET plate, I have just had a little go at removing the existing unit - easy peasy.......... so off to Screwfix as they have a like piece of kit

Plumberpro :

Ok ,all the best , come back here if you need any more help. Please don't forget to rate your answer , thanks

Customer:

Ok thanks a mill, cheers

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