Fix loose air-cond wiring

Q1: I own a Mercedez-Benz CLK of model year 2000. 

The  air-conditioning shuts down whenever I hit a speed bump and comes back on when the car rolls over a second bump. I can turn it back on also by giving a firm slap at the front passenger side of the fascia just below the glove compartment where the cooling coils are attached.

How can I normalise the  situation?

Gan
Kuala Lumpur

Your car has loose air-conditioning wiring. Have a licensed automotive electrician sort it out immediately before the trouble causes a major electrical failure.

 
Q2: There is a knocking noise whenever I brake. It appears just before the car comes to a complete stop, emitting a repeated “duk duk” sound. Interestingly, it happens only after the car has travelled some 15 minutes and the sound gets louder from then on. The sound seemed to be coming from from the right side.

Brake calipers appeared to be in good condition, and the suspension and undercarriage are all right.

Mr  Lee
Subang Jaya

Normally, the front brake disc is fitted with an anti-rattle plate and metal clips hold both ends of the brake pad.

In your case, the anti-rattle plate might  not have been installed properly or it went missing after they have replaced your brake pad on the front right side of your brake. As a result, there is a knocking sound whenever you apply the brakes.

Also, a worn-out anti-chat spring on the caliper pad can cause unusual sound during braking.

Another component such as faulty ball joints can also lead to abnormal noise during braking, assuming that suspension bushings, mountings and shock absorbers are working normally.

In this case, your mechanic should use a suspension knock detection instrument to identify the  cause of the problem.


Q3: I own a 2001 Proton Wira Aeroback. The 1.5-litre automatic transmission car has run up a mileage of 103,000km in the last 10 years.

But in the past four months, the engine indicator light would suddenly light up after I have driven the car for around 15 minutes especially on the highway at between 90kph and 110kph.

The Proton service centre checked the car and told me a faulty oxygen sensor might be causing the problem, and advised me to change it. They didn’t sound confident about their answer.

Up to now, the car has not stopped or failed on me despite it being driven up to 250km at a stretch.

The indicator light disappears when I stop the car for a short while but it re-appears after 15 minutes of driving. The light does not flash but its persistence worries me.

Suresh
Kuala Lumpur

When the indicator light comes on, it means that your engine’s EFI (electronic fuel injection) system has detected some electronic or sensor/s problem.

When the ignition switch is turned on, the engine indicator lamp normally lights up and when the engine has already started, the light should turn off automatically a few seconds later.

Since your car has already clocked a high mileage, there will already be a number of components that have been subjected to wear and tear.

Clean and check all wiring connections/connectors including grounding points, and replace old wires and insulate the harness.

This might fix your problem.