eberspacher problem

[Dave70]

Hello,me again,well,today,managed to get heater to fire up[engine running],loads of smoke,ran for about 5 -10 mins,getting nice and hot,[thought i'd cracked it]but fan went into slow mode,so, switched off,but no normal shut down,ie,burning off fuel ,cooling,etc anyway tried again,nothing,so primed fuel through,next attempt,loads of smoke,heater fired,and ran HOORAY! this time heater ran over the 10 min period,so thought this time had sorted it .But no, heater got HOTTER and HOTTER,and did not switch off by itself,so i assume i should suspect the o/heat thermal switch. Couldn't find any blockages,ie ducting,air intake etc incidently,the o/h switch on this heater does not have reset button. on these happenings,should i assume that the e.c.u. and elecs. are o.k.? or not any help appreciated cheers,dave.

 

[David2452]

It sounds like the sensor is allowing it to run away a bit, a simple resistance test will confirm, ECU sometimes misinterprets the resistance but the sensor should be the first call. Another possibility is the set point generator, commonly known as the room thermostat.

 

[haydude]

It is unclear what is the problem. The heater is supposed to get hotter and hotter ... in my case (D5 and D5LC) it is hard to hold a hand in front of the first vent which is 4m of ducting from the heater when it runs at max.
If you start it from about 5 to 8 degrees inside temperature, the heater can run for two/three hours at max speed before slowing down once the pre-set temperature on the thermostat is reached.

As I understand if the overheat sensor does not work then the heater will not even start and symptoms can be that the fan runs without the heating to start.

If instead it runs at max speed even after reaching the set temperature, problems could be:

1) the cabin temperature sensor is disconnected or not working and thus the heater probes the temperature at the air intake. If the air is taken from outside it will be always cold and the heater will never slow down
2) the thermostat isn't working or it is disconnected and thus the heater will run always at max speed.

 

[Dave70]

Hello,thanks for info,not sure how to do a resistance test,or what reading should be but i will give it a go. The air intake is taken from inside,and i was advised always to start heater at max on room stat,and turn down to half heat as required,which worked o.k. before,also not sure how to test room stat.cheers,dave

 

[ghostlymoron]

Try running it again then direct a hair dryer or fan heater at the thermostat and see if it turns off or down. The pre start test sequence checks if all sensors are functioning.

 

[Pagetslady]

It sounds like the sensor is allowing it to run away a bit, a simple resistance test will confirm, ECU sometimes misinterprets the resistance but the sensor should be the first call. Another possibility is the set point generator, commonly known as the room thermostat.

I have a D4 which I bought a room thermostat for but when wired into the system made no difference at all the unit still worked on its internal thermostat, I have unplugged it and assumed it was faulty, but perhaps I should have disconnected the internal one, any help much appreciated
Mike

 

[David2452]

I have a D4 which I bought a room thermostat for but when wired into the system made no difference at all the unit still worked on its internal thermostat, I have unplugged it and assumed it was faulty, but perhaps I should have disconnected the internal one, any help much appreciated
Mike

If you mean a room sensor then the internal one does need disconnecting if you install one.

 

[David2452]

The pre start test sequence checks if all sensors are functioning.

Basically so, but not all faults are picked up.

 

[David2452]

Hello,thanks for info,not sure how to do a resistance test,or what reading should be but i will give it a go. The air intake is taken from inside,and i was advised always to start heater at max on room stat,and turn down to half heat as required,which worked o.k. before,also not sure how to test room stat.cheers,dave

Download a manual, you will find all the information you need.

 

[Dave70]

It sounds like the sensor is allowing it to run away a bit, a simple resistance test will confirm, ECU sometimes misinterprets the resistance but the sensor should be the first call. Another possibility is the set point generator, commonly known as the room thermostat.

Hello,managed to sort temp.switch today,switched on heater,fired up o.k. ran for about hour or so,seems to be o.k. heater did proper shut down when turned off,so hopefully sorted,[we shall see] Anyway,i am going to forget all about heaters ,and other boat jobs for now anyway,Thanks for all your help every one have a good xmas and all the best for new year,Dave

 

[Pagetslady]

If you mean a room sensor then the internal one does need disconnecting if you install one.

Thank you David