The heater control assembly changed three times across MGF/TF production, with one further variant specifically for the LE 500. Pre-XD511058 MGFs use one assembly (non-illuminated knobs only). Post-XD511059 MGFs split into two variants, non-illuminated knobs and illuminated knobs, because within the Mk2 facelift era, illumination was offered as an option.
The standard MG TF uses a fourth assembly with its own illuminated-knob specification. The LE 500 MG TF uses a specifically modified assembly without the integral fascia finisher, paired with a separate finisher panel ordered alongside, because the LE 500's brushed-alloy fascia treatment required a different finishing trim approach. Ordering the correct assembly requires knowing the car's VIN (for MGF), the model (MGF or MG TF), and whether the knobs are illuminated, visible immediately by whether the knobs show a small backlit indicator when the headlamps are on.
Heater Control Knobs, Finish by Era
Five knob variants are catalogued, always supplied in sets of three (one for each of the three control positions: temperature, air distribution, fan speed). Pre-XD511058 MGFs use black knobs (non-illuminated). Post-XD511059 MGFs use black/alloy two-tone knobs, catalogued separately in non-illuminated and illuminated versions. MG TFs up to VIN 4D627889 use all-alloy knobs (illuminated); from 4D627890 onwards a revised all-alloy knob with a different part number is fitted.
The catalogue contains a useful backward-compatibility note: if post-XD511059 MGF black/alloy knobs are unavailable, the earlier all-alloy MG TF knobs (JFD000070 specification) are a visually pleasing substitute. An MGOC polished-knob upgrade set is also catalogued as a styling alternative to the factory finishes.
Graphics Plate and Illumination
The heater control graphics plate, showing the temperature and distribution symbols that sit behind the knobs, is catalogued in four variants matching the control assembly variants: pre-XD511058 MGF, post-XD511059 MGF non-illuminated, post-XD511059 MGF illuminated, and MG TF. On illuminated cars, a bulb and bulbholder assembly is catalogued as a discrete service item (two per car, one for each of the two illumination positions). A failed illumination bulb leaves the affected area of the graphics plate dark at night, a simple bulb replacement once the control assembly is withdrawn from the fascia.
Control Cables and Fan Speed Switch
The heater control operates the air distribution flap and the temperature blend (via the water valve on the engine bay side) through two cable-operated mechanisms. The air distribution control cable (JFF100830 specification) routes from the distribution knob to the distribution flap in the heater unit. The temperature control cable (JFF100840 specification) routes from the temperature knob to the heater water valve on the engine bay side. Both cables are catalogued individually along with their mounting clips (two per car).
Cable failure typically manifests as a control feeling stiff, slack, or failing to move through its full range, a stretched cable can give the symptom of heat "leaking through" even with the control set to cold, because the temperature cable isn't fully closing the water valve. The rotary fan speed switch is an electrical switch (not cable-operated) catalogued as a single variant across all MGF and MG TF production, simple ordering and a common replacement as the switch contacts degrade.
Fitting and Fascia Access
The heater control assembly is mounted to the fascia with dedicated screws catalogued individually (six for the main control assembly mounting, four for the securing screws). Access for replacement is through the centre fascia panel, which removes as an assembly along with the radio and the heater controls together. An AC-equipped car does not use a different heater control panel, AC switching is handled by separate fascia switches catalogued on the Steering Lock, Switches & Horns page. Heater control replacement is a moderately complex job because of the behind-fascia cable routing and the need to correctly adjust cable travel after refitting to ensure the water valve fully opens and closes across the knob's travel.