Parts of the Truma 3001/3002
The fan (TEB2)
The TEB2 Fan unit is used to blow warm air throughout the vehicle via ducting. The fan is controlled by the switch on the top right of the heater. It has a few settings, Off, On Manual and 5 speed levels and Automatic.
Looking at the PCB which is located in the cover that houses the motor we can see a very primitive speed control circuit. The 27Ohm 5W resistor is a ballast and the Philips BD166 is an NPN bipolar transistor. The visible thermister OR the potentiometer from the control changes the bias on the base controlling the speed.
In the event that the motor goes bad, it often fails in two ways, firstly the carbon brushes are exhausted which leads to intermittent operation and eventually no operation, OR the bearings can fail causing insufficient performance. A third and fairly common failure mode is the RFI capacitor from the +ve to ground goes short circuit, in which case this will destroy both the transistor and the resistor before blowing the fuse (if you have a fuse, otherwise it may cause a fire).
The RFI capacitor is generally a 0.1uf ceramic, but actually any 1kv ceramic from 0.01 to 0.5 will do the job just fine, but don't cut back the leads too far because there's no solder point on the motor so you'll want to use the remaining lead which is spot welded on.
If you have a daily TEB/2 and don't want to repair it yourself, then DarkStar Labs repairs these with new motors and electronics for far less than a new one, to take up this service contact us.
The Mains Control Board
This board controls the mains (240v) powered electric heater in the S300x unit. There are three relays which each in turn switch in 500w, 1000w and 2000w heating elements. The pin header connects to the temperature/mode control knob, the jack connects to the temperature probe and the press-fit connectors connect to the mains, and the heating elements. This board has no control over the fan (TEB/2) or the Gas system.
The Relays often do fail and are EBERLE 0529 01 1303 02, which is a 250V 10A relay with a 12V coil. You can replace them with the same relays or any other relay that meets or exceeds the spec with the same footprint. If you don't want or can't change them yourself then we do offer an exchange repair service.
The IC is the CA 741E is a DUAL channel OP-AMP Datasheet but these rarely fail. The larger transistor is the BD138 from fairchild Datasheet PNP, rated at 60v and 1.5A. The PNP Transistor BC327-40 in the TO-92 package is rated 45V 0.8A 0.625W Datasheet.