Long-time customer's Perodua Kancil with modified injection wiring and idle-up control fault

Sifu White explains what happened

Prices, repair times and warranty terms mentioned in the video applied at the time. Ask the workshop about current arrangements.

It is surprising that the customer moved far away but still returned to me. He says that many other places could not solve the problem, so he wanted Sifu White to handle it. We previously installed a compressor in this Kancil that lasted almost ten years. After later repairs elsewhere, some parts lasted only about a year.

The customer had replaced the compressor and several air-conditioning parts elsewhere, but the problem remained. We needed to inspect the car again to determine whether the cause was truly in the air-conditioning system or elsewhere.

Inspection shows that the mechanical air-conditioning system is sound. The cause is wiring. At engine idle, there is a repeated clicking noise. The car uses a modified fuel-injection system, so the engine wiring has to be corrected. An ECU signal is not reaching the control circuit. When idle RPM is too low, the system cannot raise idle correctly when the compressor switches on.

An amplifier or controller can adjust idle RPM, but adjusting the box alone does not solve this case. The key is identifying the correct signal wire. The technician needs knowledge of both engine management and air-conditioning wiring. Sometimes a mechanic understands only the engine while an air-conditioning technician understands only the A/C system, making cross-system faults easy to miss.

This fault requires both types of knowledge. Thank you, boss. Is there a warranty? The video states that this repair carries a one-year warranty. Do not worry.

Separate component failure from power and control faults

Pressing A/C is a request; the vehicle still has to meet its operating conditions. Controllers, sensors, relays and wiring work together to determine whether a component runs. A compressor that does not start may have an internal fault, or it may not be receiving the required power or command. Before replacement, the technician needs to establish where the failure occurs in the actual circuit rather than treating the visible symptom as the diagnosis.

A fault code helps direct testing, but it does not always identify a part to buy. Actual output, connectors, ground connections and circuit behaviour under load may all need verification. Added relays or bypass wires can also change the original control relationships. After addressing an electrical fault, the air-conditioning needs to be operated again to check the original complaint. A cleared code or newly installed part is not sufficient evidence of a successful repair by itself.

Why hot weather or idling can reveal a cooling problem

Air-conditioning has to move cabin heat outside. Hot weather and sun-heated seats and trim increase the cooling load, while airflow through the condenser affects heat rejection. Airflow conditions change between driving and standing still. “Warm at idle, colder while moving” is therefore a useful clue, but it does not prove a fan failure without testing the fan, refrigerant circuit and relevant operating conditions.

Assessment can include condenser and radiator condition, fan operation, engine-cooling data and refrigerant specification. Some vehicles change A/C operation when engine or other protection conditions are active. Vent temperature also depends on ambient conditions, humidity, recirculation and fan speed. A reading from one video is not a universal pass mark for every car. Meaningful before-and-after comparisons should record comparable test conditions.

What to tell the workshop about your own car

You do not need to guess a part name first. A clear description of what actually happens is often more useful for reproducing the complaint than requesting a particular replacement.

• Mention previous wiring changes, added relays or controller replacements.
• Compare idling, driving, midday and evening behaviour.
• Include the model, year, recent repairs and what changed before or after the symptom began.