Parts for your 2018 Mitsubishi Asx-Heater tap

2018 Mitsubishi ASX heater‑tap: what’s fitted and what to service

Short answer: a heater‑tap isn’t used on the 2018 Mitsubishi ASX. The ASX (also sold as RVR/Outlander Sport) regulates cabin temperature with an air‑mix/blend door inside the HVAC box, not by shutting off coolant to the heater core.

Why this call? Referencing technical sources:

• Mitsubishi Motors Workshop/Service Manual for ASX/RVR/Outlander Sport (GA‑series, 2010–2019), Group 55A – Heater, Air Conditioning and Ventilation: temperature is controlled by an electronically driven air‑mix damper, the heater core has constant coolant flow (no water valve shown in the cooling or HVAC circuit).
• Mitsubishi ASA electronic parts catalogue for 2018 ASX (GA‑series): lists heater core, pipes and hoses but no “water valve”/heater‑tap component.
• Major aftermarket catalogues for this model/year list hoses, thermostat and heater core, but no heater control valve/heater‑tap.

So on a 2018 ASX there’s no heater‑tap to replace. Mitsubishi’s design keeps hot coolant flowing through the heater core at all times, the climate panel and A/C ECU simply swing the air‑mix door to blend hot and cold air. It’s simpler, warms the screen faster for demist on cold mornings, and removes a common leak point you’d get with an old‑school tap in the engine bay. It also plays nicely with automatic climate control because the servo‑driven blend door can make fine, quick tweaks without waiting for coolant flow to change.

What should owners and techs focus on instead?

• Coolant health: use the correct long‑life coolant and change it as per the logbook interval. Poor coolant can clog the heater core and hurt engine cooling.
• Hoses and clamps: check the heater hoses under the bonnet for softness, swelling or seepage. Replace if they’re tired.
• Air‑mix (blend) door operation: if the cabin stays too hot or too cold, suspect a sticky blend door or a faulty actuator rather than a missing heater‑tap.
• Cabin filter and airflow: a blocked pollen filter reduces heater and A/C performance, so keep it fresh.
• Bleeding air after cooling‑system work: air pockets can kill heater performance, bleed the system properly after any drain or hose job.

If there’s no heat, look for low coolant, a partially blocked heater core, or thermostat issues. If there’s constant heat with A/C on, check the blend door actuator and foam seals in the HVAC box. Installing an aftermarket heater‑tap isn’t recommended on this platform, it can create flow and control headaches the system wasn’t designed for.

Popular questions

Does the 2018 Mitsubishi ASX have a heater‑tap?
No. It uses a constant‑flow heater core and an air‑mix/blend door controlled by the A/C ECU. Temperature changes come from air blending, not a coolant shut‑off valve.

Why is my ASX still blowing warm air with the A/C on?
Because the heater core is always hot, a stuck or mis‑calibrated blend door can leak warm air into the vents. Check the blend door actuator, HVAC control calibration, and the cabin filter. Also confirm the A/C system is charged and the condenser fan is working.

What maintenance keeps the ASX heater working well?
Stick to the correct long‑life coolant and change it on time, inspect heater hoses and clamps, replace the cabin filter regularly, and bleed the system properly after any cooling work. If heat output drops, consider a gentle heater‑core flush.