Diesel heater not heating

Mfumu Nyanga · Member

Diesel heater not heating

blaze · Guru

bad earth, poor connection, broken wire internally, wiring to small
cheers
blaze

Mfumu Nyanga · Member

Thanks for the response, blaze. The voltage drop seems to be between the input to the circuit board in the main heater unit and the output to the glow plug. I've actually been using the unit since last July and it has performed great until the incident described, which would seem to indicate good connections all around, except perhaps on the circuit board itself and there's no way I can do anything about that. Are there places that can check out this sort of thing? I can try installing larger wiring but I don't have much hope with that either given the history of flawless performance.

jegog · Senior Member

Firstly measure all voltages with the meter negative lead on the negative battery terminal.
And I assume that you are using a digital meter.
If the voltage into the circuit board is very close to the battery voltage but the voltage at the glow plug is 8.4V. then it could the switch which switches power to the glow plug which is faulty or the connection out of the circuit board or the connection to the glow plug.
Disconnect the lead to the glow plug and measure the voltage at the lead.
Also with the glow plug both connected and disconnected measure the voltage at the circuit board's glow plug output.

Mfumu Nyanga · Member

Thanks, jegog, will check this out.

travelyounger · Guru

Hi check the condition of your battery's I had my heater fail due to low voltage also some heaters do not work when temperature below 02

Aus-Kiwi · Guru

Have to ask ? White smoke ? Low voltage ? Is there any chance of water in fuel
??

Mfumu Nyanga · Member

travelyounger Have had this heater working for eight months without a problem including in a couple of sub zero conditions and the battery was replaced only early last year. I check it frequently when on the road. Thanks for the suggestion.

Aus-Kiwi Don't think so, it's been bone dry around here for months, but it should be easy to check as I'm sure diesel and water don't mix and would be visible in the tank. Thanks.

PeterInSa · Guru

MN, my understanding is that if the heater is run on low for a number of hours, again and again without running on full to burn the carbon off, problems can rise similar to yours, to me, it applies to all heaters not just the units in the article below. I have seen demos re taking the heater apart and removing carbon. Article does mention white smoke.

irp-cdn.multiscreensite.com/c113b2db/files/uploaded/airtronic-flame-tube-carbon-removal_81kYEZsKRLOg9gxlQ5Ak.pdf

Peter

Aus-Kiwi · Guru

Is it working now ? Be interesting to find out, the issue .

Mfumu Nyanga · Member

Thanks for the interest. No nothing has seemed to solve the problem, the conclusion being that some component of the circuit board has gone belly up and neither I nor my friend who's been helping have the knowhow or tools to troubleshoot such electronics. We've received no response from the supplier despite repeated requests and as the purchase is more than six months old eBay isn't interested. I've ordered another unit that should be here early next week. We're hoping to exchange just the heater unit. I'll post here if it works, which will confirm that the fault is in the circuit board.

bruceg · Veteran Member

Almost all of these heaters use an old fashioned electro-mechanical relay to switch the glow plug on. (Too much power / too much in-rush for silicon electronics to survive.)

Good relays use bronze armatures with silver alloy contact faces to 'make' and 'break' the circuit plus a reverse fitted diode. The bronze ensures solid 'contact' with no bouncing while the silver resists burning at the (tiny) first point of contact and the diode redirects electricity stored in the relay's coil backwards, around the contacts to 'snub' out arcs when the points 'break'. (Cheap designs omit the diode.)

*BUT* even the best silver alloy *WILL* get burnt after thousands of on/off cycles (particularly if the diode fails). As you use your heater often/regularly this is the most likely failure. Now for the good news - if it is just a diode or a relay it is a cheap and DIY fix!

The diode is easy to test, it will read high ohms in one direction and almost none in the other. Even the cheapest multi meter will have an ohms test range.

The relay is a little harder, you have to look at the contacts; if they are shiny they are good, if blackened they are burnt. While lots of relays have clear cases, many don't, but you can usually pries the case open with a small screw driver to see.

If either has failed I recommend replacing both. Your local Jaycar, etc will have comparable parts for less than $20. De soldering, remove & replace and re soldering are easy.

The new diode *MUST* go in with the white band near one end the same way round as the old one was fitted. If you can't see the markings on the burnt one then the white band goes towards +12V and the other end towards 0V. Depending on the circuit arrangement only 1 of these (+12 or 0V) will be able to be tested while the circuit is 'off'.

A good auto electrician will be able to do this, and, if you don't make it an urgent job, will do it for a good price.

bye.