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Roadster Heater Control Issues

Much like the fortwo 450, the Roadster uses bowden cables to control much of the heating system. A bowden cable is exactly like the brake cables you had on your BMX when you were young. It’s a steel cable running through a sprung wound metal tube, all covered in plastic. When 1 end of the cable moves, the other end moves.

Problems With Bowden Cables

On your bike, the bowden cables only pulled and never pushed so the only issues you had back then was frayed cables not sliding, rust inside the cables stopping movement and the cable eventually snapping. However, on the Roadster, these cable don’t just pull, they also push.

Although there isn’t much force being put into the cables, it brings in the problem of kinking. Over time, the internal cable can bend at the ends where it isn’t in the sheath. You will have almost no chance pushing a kinked wire. If anything, it’ll make it worse. You have a small chance of pulling a kinked wire.

Problem Sliders

Below are the 4 heater controls.

1 – Recirculated or fresh air
2 – Heater temperature
3 – Heater output direction
4 – Blower power

Of these, controls number 1, 2 and 3 use bowden cables to control the various parts of the heater. Control number 4 is just a plain switch. If that’s not working, look here.

1 – Recirculated Or Fresh Air

Look under the dash on the passenger’s side (both LHD and RHD).

You’ll see the black box with the recirc flap in it. the flap is controlled by the white lever. The end of the lever is connected to the bowden cable coming from control lever 1. Check that the cable isn’t kinked or rusted. Try moving both ends of the cable at the same time to feel if there is unnecessary resistance which could denote rust or internal damage.

The other end that connects to the heater control slider can be accessed by removing the passenger airbag and looking to the right (RHD car).

On a LHD Roadster, remove the speedo and the surround and look to the right.

Left Hand Drive – Q0008763V003000000
Right Hand Drive – Q0011646V002000000

2 – Heater Temperature

Underneath the central heater vent is the lever and the top part of the cable.