How to : Add a warning lamp to Trumatic S3002 with TEB -12V Trumavent Fan

Introduction
I have found it very easy in the past to accidentally switch the fan on to manual or auto simply by wiping the top of the heater to clean it. The last time this happened my Triton 430GT was parked up at home without the electric hook up. By the time I discovered it, the battery was completely flat at 1.2V and most likely irreversibly damaged.
Brief
To install an LED warning lamp to indicate that the fan was running, to be bright enough to see in daylight and small enough to cover up at night if required.
Investigation and Design
My initial thought was to simply attach a 12V LED across the control switch. On removal of the front panel this proved to be very difficult because of the switch connection at one end and a PCB at the fan end. Not wishing to get involved with those items I explored the possibility of a current sensing relay in the supply to the fan but these were too expensive and complicated for me to set up. Having removed the plastic cover from the end of the fan it exposed two big motor terminals with the supply wires soldered to them I decided to solder the positive side of the LED to the positive supply to the motor and the negative to a suitable earth.
The S3002 has a blank plug at the top left of the heater which is used for other models, not in use on mine. This is where the LED was to be fitted. The two wires from the LED would then have to come through the heater body and across the top of the fan which would get hot in normal operation so heat protective sleeving would also be required.
The complete job cost about £7.00 and took me about 2 hours.



Here we have the Trumatic S3002, the blank plug to the left of the fan control switch is where the LED will be fitted.
The front comes off by simply grasping finger tips behind the top sides and pulling forwards to overcome the spring clips. The front can then be lifted slightly and eased to one side to inspect the internals.



Now we can see the fan control switch cable and white plug which simply pulls out. Once the front panel is completely removed, recover the thermostat knob from the right hand side. The inside of the heater will no doubt now require a good clean of all the dust and cobwebs. It might also be worth replacing the ignitor AA battery at this stage also.



Truma recommend cleaning once a year before the heating season, obviously not done by me or at its last service 6 months ago.



Moving in to the wardrobe, loosen the plastic side trims which are glued in place with a sharp knife. 4 screws can then be removed and the wooden cover moved to the back of the wardrobe to expose the rear of the fan.



Now we can see the fan control wire running across the top of the heater. The rear of the fan has a black plastic cover. This can be removed by unscrewing two hexagon socket screws. The cover comes loose but the wires to the circuit board were not disconncetd, just left to dangle loosley.



These are the two items I bought from a well known auction site.
I chose a 12V LED with a fan symbol which lit up yellow. I chose the 8mm lamp as opposed to a 12 mm lamp as I thought that size would be quite visible but less obtrusive.
Also here is 8mm heat resistant sleeving sold in metre lengths, I bought one metre. Total cost including p&p was £6.79.



The left hand plug was removed from the front casing and drilled to accept the LED. 3mm pilot drill then 8mm drill. The LED was then mounted in the plug and secured with the supplied nut and shakeproof washer.
The LED connecting leads were extended with some light gauge twinflex with blue and brown wires. The connections were soldered and then insulated with heat shrink. The heat resistant sleeving was then installed over the the wires and pushed right up on to the LED body with a snug fit.



This picture shows the LED installed in the front casing ready to re-fit. The black heat resistant sleeving can be seen alongside the white fan control cable. The ends of the LED extension lead are looped round to show an earth crimp on the negative (blue ) lead and the positive brown lead stripped back ready for soldering to the fan motor terminal.
It is at this stage of writing that I realise I have not followed the Eriba colour code, oh dear! But then neither has Truma as their pos and neg are red and black!



The fan motor with the LED's brown wire soldered directly to the motor supply red wire. There is another hexagon socket screw lower down which has been loosened to accept the earth wire.



Earth wire connected up.



Fan motor case replaced and screwed up. LED extension cable fixed at motor end with cable tie to supply cable and at heater end with a couple of cable ties to the control cable. The loop has been left to enable the front casing to be removed at a later date and moved to one side without disconnecting the LED connecting wires.
After testing the wooden cover was screwed back in place and the plastic edge trims replaced with glue.



Final pic shows the heater all boxed up and running. The LED lights up as required in manual or auto. The brightness of the LED varies with the speed of the fan but even at the lowest speed it is bright enough to see in daylight.

So, this is my £7 modification to save a £110 battery and a lot of inconvenience.