Eberspacher Combitronic fault

[david lloyd]

Had a problem with my Eberspacher space/water heater a few months ago which simply wouldn’t fire up when the heating was turned on. Took it to an Eberspacher repairer near me in North Yorkshire who diagnosed ‘low voltage’ and recommended I replace the two leisure batteries. They did that and, as the old ones were ten years old, it made sense. 

Been using the MH regularly since but only the hot water (on diesel) as heating not required. However, last Friday toured down to Stow on the Wold (in filthy weather) and on arrival found the Combitronic wouldn’t fire up again. Batteries only a few months old, on charge at home before leaving, driven around 240 miles so expected batteries to be fully charged. Tried both water and heating several times for next 24 hours without success so contacted a service agent near Dudley who has had his diagnostic laptop on it today - result - low voltage after driving 65 miles in sunshine with solar on roof. Just to complicate things, by Monday the weather has improved and the Combitronic water heater started to work but the printout shows that shortly after turning the heater on there is an expected drop in voltage to just over 8v which then should return to +12v once the burner is lit but in my case the trace shows it trying to light about eight times then gives up and turns off within about 10 seconds. They, not we, had the time today to stay and carry out the necessary checks to ascertain the cause of the prolonged power draw that in turn causes the ‘low voltage’ error. My plan was, armed with the print out I can return to the original Eberspacher repair shop near home and get them to now trace the fault that may not have been the old batteries after all.

This evening I was perusing an old post by ‘my shell’ in august 2014 who had a similar problem on his Pioneer Renoir and had bought a new battery to no avail. He quotes seeing a voltage of 12.3 at the heater control module with the engine running but a voltage of  14.5 from the alternator at the same time. This led him to check the two relays under the bonnet behind the front grill which are subjected to a great deal of water in their lifetime. He found all the terminals coated in Verdi green and, rather than fiddle about cleaning them up, bought two new heavy duty relays and fitted those. The heater then worked and the voltage at the module went up to 13.2v. This appeared to cure his problem with the heater not firing up due to ‘low voltage’. 

It’s an excellent nugget of information and upon our return to the site I pulled one of the relays to find they are well coated in verdigris and pretty grotty. I can clean up the relay contacts to see if it works but really wanted to know, should I wish to change the relays, the correct part numbers for suitable heavy duty relays?

David

[rayc]

 "that shortly after turning the heater on there is an expected drop in voltage to just over 8v which then should return to +12v once the burner is lit"

 

That is a massive volts drop. My D2 heater drops the voltage by about 0.3v whilst the glow plug is heating up

Edited August 9, 2023 by rayc

[david lloyd]

It certainly is Ray but that’s what the graph shows. The technician said it can still operate at around 10v but then should still go straight back up to +12v whilst running. Not sure yet if the relay cleaning/replacement will overcome that sort of drop but worth trying before taking it back to the original Eberspacher agent that sold me the new batteries to overcome the problem.

David

[Brian Kirby]

David, given that the problem appears to lie in the corroded relays, the simplest remedy would appear to be to change the relays for new - which I assume is why you asked if anyone had the relevant part number.

As it seems  the relays are accessible and you have already removed one for inspection, why not pull them both and look for their makers name and part codes/descriptions?  Then, armed with that info do a "Google" for the maker and part codes/descriptions and you should find you get not only the originals and possibly modified equivalents but also equivalent relays from a number of alternative makers.

These relays are generally pretty standard, readily available, components, and are used for a variety of purposes, not necessarily related to heating applications.  Armed with that info, pretty well any auto electric factor should be able to supply suitable replacements - although it might be wise to take the originals with you to confirm compatibility.  😉

Then, thus armed, swap t'other for which, and Bob should be your proverbial Uncle!  🙂 

However, since wetting seems to have brought about the demise of the originals, I'd suggest spending a bit of effort on waterproofing the installation at the same time.  Even a reasonably robust polythene bag (assuming no adjacent ignition risk), might be sufficient.

[david lloyd]

Thanks Brian - hoping to get hold of a bit of wet/dry paper to clean up the contacts and then check again but, after reading the old post by ‘my shell’ he did indeed buy new, sealed relays so thought that would be a better long term solution. When I pulled one of the two relays the white lettering was somewhat worn (they are 17 years old) so couldn’t get any useful information from it, hence the request for information on replacements - preferably heavy duty, sealed ones.

David

[onecal]

Hi

May not be much use if they are that wet and corroded  , Replace the relays and ensure the wiring is not corroded (wicking) at the connections,  clean or replace the connections or wiring. Contact any good part supplier with your model and they will quickly advise on the correct relays or updated ones  and wiring etc' if needed for your model

Regards

Edited August 10, 2023 by onecal

[david lloyd]

Thanks onecal. As these are relays fitted by the ‘old’ Autocruise company and not Peugeot  I wasn’t sure if a parts supplier would recognise the ‘Pioneer Renoir’ model and be able to advise the correct replacement. As I mentioned earlier, the white lettering on both relays is unreadable and, although they are bound to be a fairly widely used type, I would prefer to replace them with a heavy duty, sealed type.

Some good news is that I found an emery card nail file in my wife’s possession which made an ideal tool to clean up the contacts. After that I switched the Eberspacher to diesel, turned off the solar and mains charger, put the heating on and it fired up (once I set the temp high enough) and ran for ten minutes or so without cutting out. The readout on the EC328 panel never went below 12.8v while it was on so this bodes well.

I need to carry out further checks but may still replace the relays for better ones.

David

[onecal]

That's good news , but if they were that badly damaged with corrosion I would carefully check the wiring and all connections for same. Relays are available of course and should be easily matched by any competent electrical vendor to that of yours Or contact  Contact. Eberspächer (UK) Ltd. Climate House Yeoman Road Ringwood, Hampshire BH24 3FA Phone: +44 1425 480151. Fax: +44 1425 480152 They may even as you say suggest an updated heavy duty version if available 

Edited August 10, 2023 by onecal

[david lloyd]

An update. During the recent habitation check the van had two high readings in a spot where the wall joins the floor immediately adjacent to the rear of the hot water cylinder. The technician found the reason - a leak from the large brass nut that holds the mains heating element in the end of the cylinder. However, they were reluctant to try and ‘nip up’ the nut for fear of further damage and advised I take it to an Eberspacher service agent. 
 

I had already booked it in to the original auto electricians I used for the electrical control side to try and resolve the voltage drop issue mentioned above so asked them to look at it while it was there.

Have the van back now. On the electrical side they found high resistance in one of the cables in the loom near the leisure batteries . Here there was a six way plastic block and I recall when I was using a multimeter and moved this connector it would sometimes switch the Combitronic panel off but come back on. They removed the connecting block and used bullet connectors instead. Additionally, they have replaced the charge relay with a more heavy duty one and the heater is now working fine.

The water leak turned out to be a perished rubber seal. Unfortunately, despite trying a gasket for a domestic element (from a plumbers merchant) and then ptfe tape on the threads, the leak was still there albeit considerably less than before. No parts for this model water heater are available although they are for the heater. So they were at a loss what to do next and advised I contact a good plumber.

I had considered using Bos White myself which I use on some fittings on my live steam engines but managed to get hold of a flat sided rubber seal of the right diameter from a friend (who often has something that will complete a job) put that on with the gasket also and overnight no leak detected with the pump left on to keep the pressure up.

Thank you to everyone who contributed, much appreciated.

David

[onecal]

Hi David

Well done, Yes the Boss white along with the rubber gasket may have done the trick. Tech 7 would have worked with your rubber gasket.

Great you had a friend with a good fitting one and the help from Rayc and Brian here

Regards

[witzend]

2 hours ago, david lloyd said:

An update. During the recent habitation check the van had two high readings in a spot where the wall joins the floor immediately adjacent to the rear of the hot water cylinder. The technician found the reason - a leak from the large brass nut that holds the mains heating element in the end of the cylinder. However, they were reluctant to try and ‘nip up’ the nut for fear of further damage and advised I take it to an Eberspacher service agent. 
 

I had already booked it in to the original auto electricians I used for the electrical control side to try and resolve the voltage drop issue mentioned above so asked them to look at it while it was there.

Have the van back now. On the electrical side they found high resistance in one of the cables in the loom near the leisure batteries . Here there was a six way plastic block and I recall when I was using a multimeter and moved this connector it would sometimes switch the Combitronic panel off but come back on. They removed the connecting block and used bullet connectors instead. Additionally, they have replaced the charge relay with a more heavy duty one and the heater is now working fine.

The water leak turned out to be a perished rubber seal. Unfortunately, despite trying a gasket for a domestic element (from a plumbers merchant) and then ptfe tape on the threads, the leak was still there albeit considerably less than before. No parts for this model water heater are available although they are for the heater. So they were at a loss what to do next and advised I contact a good plumber.

I had considered using Bos White myself which I use on some fittings on my live steam engines but managed to get hold of a flat sided rubber seal of the right diameter from a friend (who often has something that will complete a job) put that on with the gasket also and overnight no leak detected with the pump left on to keep the pressure up.

Thank you to everyone who contributed, much appreciated.

David

Thank You for your informative reply I,m denied the likes button but felt this deserved a reply

[david lloyd]

You’re welcome witzend, perhaps all too often we never get to hear the end results of posts on the site but if helps anyone in the future it’s worth a little time.

David