# Eberspacher Airtronic



## nipperdin (Oct 28, 2007)

Our heater has worked well for over 6 years.
But we now have a problem in that it starts okay and the fan blows out warm air but very quickly, within a couple of minutes, the fan slows down and we get very little heat.
It even does this with the thermostat round to the hottest setting.
Before it would keep blowing warm air for some time and soon get the van warm.
The fan still works okay on the cold air setting.
Has anyone any ideas as to the cause of the problem? Could it be a faulty thermostat?
Thanks


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## ingram (May 12, 2005)

nipperdin said:


> Has anyone any ideas as to the cause of the problem? Could it be a faulty thermostat?
> Thanks


I'm not an expert but that would be my first thought too.

Harvey


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## Jezport (Jun 19, 2008)

Do you have a good 12volt supply? As low voltage can cause problems.


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## Mike48 (May 1, 2005)

Its probably the battery. Try using it with the lights off. Test it when the vehicle is on EHU.


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## trevorf (May 16, 2005)

Diesel heaters use a lot of battery power on initial start up due to the pre-heater (glowplug). If it fires up OK then its not a battery problem.
Thermostat or connection from thermostat is more likely.

Trevor


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## nipperdin (Oct 28, 2007)

Many thanks for your replies.
I hooked up the van to mains electric today but the same problem happened.
A couple of minutes and the heater slowed down.
So it looks as if it is something to do with the thermostat.
Oh dear, more expense!
Thanks again for your suggestions.


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## erneboy (Feb 8, 2007)

It sounds as thought it needs a service. There is a little gauze in it which fails over time, when that happens it will not ignite properly. Alan.


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## TR5 (Jun 6, 2007)

After the thermostat, the fan speed is also controlled by the heat output of the unit.
It could be that there is a fuel line filter which is partly blocked, causing a starvation of fuel. The heat output being reduced, so the fan will start to run slower, as if it is being modulated by the stat.

Worth checking the fuel line first!

Another cause could be airflow. If a partial blockage on the air intake, the unit will start to cut back on heat output, and slow the fan.

HTH


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## skiboycey (May 21, 2009)

With respect to the previous posters the information they have collectively given is not terribly informative nor informed apart from TRS who gets somewhere a little closer...

Your heater is probably giving up for a number of reasons which I've listed in order of likelihood. I assume you have eliminated 'obvious' faults lke blown fuses, faulty control units (they work or they don't broadly so are easy to discount), bad wiring (check all connections but normally they are very reliable), old or poor diesel or water contaminated fuel (as found in boats when left for many years in damp weather) and other such stuff.

1/ The air intake is blocked. There is a gauze over the intake of an eberspacher and with time this attracts dust, hair and other rubbish which collects to form a partial blockage. The heater will fire and the fan will come on but quite quickly the PCU will detect a heat exchanger overheat and flame out the boiler whilst running down the fan. When the unit stops it will often not fire for some time afterwards. Fix this by cleaning out the gauze over the inlet which you may need to spend some time finding if it is well built in. This needs doing about every few weeks to a few months depending on where the intake is sited. It almost always cures any problems.

2/ Low leisure battery. This will lead to a glow-plug underheat and can result in a flame out especially at low temperature settings when the unit is constantly re-firing all the time. Try running it flat out when it will not need to re-ignite and see if it works like that. Normally when the battery is a bit too flat the unit will try to fire but after three goes will fail and shut down for a few minutes. If you re-set it it will try again. Charge everything fully and see if this works.

3/ The glow plug and gauze need changing. This is a cheap (about 20 quid) spare part from any dealer (Halls Electrical are good) and you need to get the special tool to change it at the same time for another 8 quid. Change both and see if it is cured. Often if the glow plug is going the unit will produce lots of white paraffin smoke from the exhaust as it tries to fire in cold weather. In warmer weather it will work fine... It will often fire once then flame out on subsequent tries then 'sulk' all night and not work till the next day. This should be changed yearly in any case to ensure the unit works properly.

4/ The fuel pump may be weak or has failed. You should hear it 'ticking' when the unit fires. Very quickly at first then slowing down. If you can see the fuel pipe you should see the fuel surging along the pipe as the pump 'ticks' (you can see the bubbles normally. If there's no ticking check the connection to the pump by pulling it apart and pushing it together again. They are often sited in poor places and get dirt and corrosion on them. A blast of WD40 on everything often helps. Check the earth to it as well. If the pump is not fully working the unit will starve of diesel and shut down.

5/ The internal catalyst gauze gets corroded and worn out with time. It seems to get a white deposit on it which chokes the catalyst gauze and which is very hard to remove. It is probably impurities in the fuel which are left after combustion. The easy way to fix this is to change the burner tube for about 140 quid. It takes about an hour to completely dismount the unit from your vehicle and take it apart and you'll need a Torx fitting to get the heater tube out. All very easy if you are mechanical and you'll be amazed how little is in the unit when you dismantle it. Get the gasket kit as this will fall apart when you take the unit apart. Rebuild and it should work. You can de-coke the burner tube using a combination of caustic soda and a blowlamp plus lots of hammering and swearing. I did this and it worked but for the 140 quid I'd probably just buy the part next time. Google 'Eberspacher Repair' or something like that and you'll find information.

The whole unit is very simple and easy to work on. Don't let any nay-sayers tell you it needs to be entrusted to a competant engineer etc. It's not dangerous to fiddle with (if you get it wrong it just won't work) nor will you damage it as there's only about 10 bits to it and all are replaceable. If you can fix a toaster or a lawnmower you'll have no problems with an Eberspacher. If not pay a 'competant' engineer a fortune to do a scappy job instead!!!!

Good luck...

Cheers, Mark


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## skiboycey (May 21, 2009)

With respect to the previous posters the information they have collectively given is not terribly informative nor informed apart from TRS who gets somewhere a little closer...

Your heater is probably giving up for a number of reasons which I've listed in order of likelihood. I assume you have eliminated 'obvious' faults lke blown fuses, faulty control units (they work or they don't broadly so are easy to discount), bad wiring (check all connections but normally they are very reliable), old or poor diesel or water contaminated fuel (as found in boats when left for many years in damp weather) and other such stuff.

1/ The air intake is blocked. There is a gauze over the intake of an eberspacher and with time this attracts dust, hair and other rubbish which collects to form a partial blockage. The heater will fire and the fan will come on but quite quickly the PCU will detect a heat exchanger overheat and flame out the boiler whilst running down the fan. When the unit stops it will often not fire for some time afterwards. Fix this by cleaning out the gauze over the inlet which you may need to spend some time finding if it is well built in. This needs doing about every few weeks to a few months depending on where the intake is sited. It almost always cures any problems.

2/ Low leisure battery. This will lead to a glow-plug underheat and can result in a flame out especially at low temperature settings when the unit is constantly re-firing all the time. Try running it flat out when it will not need to re-ignite and see if it works like that. Normally when the battery is a bit too flat the unit will try to fire but after three goes will fail and shut down for a few minutes. If you re-set it it will try again. Charge everything fully and see if this works.

3/ The glow plug and gauze need changing. This is a cheap (about 20 quid) spare part from any dealer (Halls Electrical are good) and you need to get the special tool to change it at the same time for another 8 quid. Change both and see if it is cured. Often if the glow plug is going the unit will produce lots of white paraffin smoke from the exhaust as it tries to fire in cold weather. In warmer weather it will work fine... It will often fire once then flame out on subsequent tries then 'sulk' all night and not work till the next day. This should be changed yearly in any case to ensure the unit works properly.

4/ The fuel pump may be weak or has failed. You should hear it 'ticking' when the unit fires. Very quickly at first then slowing down. If you can see the fuel pipe you should see the fuel surging along the pipe as the pump 'ticks' (you can see the bubbles normally. If there's no ticking check the connection to the pump by pulling it apart and pushing it together again. They are often sited in poor places and get dirt and corrosion on them. A blast of WD40 on everything often helps. Check the earth to it as well. If the pump is not fully working the unit will starve of diesel and shut down.

5/ The internal catalyst gauze gets corroded and worn out with time. It seems to get a white deposit on it which chokes the catalyst gauze and which is very hard to remove. It is probably impurities in the fuel which are left after combustion. The easy way to fix this is to change the burner tube for about 140 quid. It takes about an hour to completely dismount the unit from your vehicle and take it apart and you'll need a Torx fitting to get the heater tube out. All very easy if you are mechanical and you'll be amazed how little is in the unit when you dismantle it. Get the gasket kit as this will fall apart when you take the unit apart. Rebuild and it should work. You can de-coke the burner tube using a combination of caustic soda and a blowlamp plus lots of hammering and swearing. I did this and it worked but for the 140 quid I'd probably just buy the part next time. Google 'Eberspacher Repair' or something like that and you'll find information.

The whole unit is very simple and easy to work on. Don't let any nay-sayers tell you it needs to be entrusted to a competant engineer etc. It's not dangerous to fiddle with (if you get it wrong it just won't work) nor will you damage it as there's only about 10 bits to it and all are replaceable. If you can fix a toaster or a lawnmower you'll have no problems with an Eberspacher. If not pay a 'competant' engineer a fortune to do a scappy job instead!!!!

Good luck...

Cheers, Mark


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## erneboy (Feb 8, 2007)

Skiboysey, Thank you for a most informative post. There was no need to be quite so dismissive of other peoples efforts to help, most of them did contribute useful suggestions. 

For myself, not knowing anything about the OPs abilities I suggested a service because it is quite possible that an unskilled person could dismantle the unit and have no idea what to look for, how to test it or how to reassemble it. That could lead to irreparable damage or worse, Alan.


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## Snelly (Aug 20, 2005)

Mine does that when my mh is low on fuel... as it takes its supply from my mh diesel tank, when it gets near a quarter the heater wont fire up. Fill it up and probelms solved.


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