Wilson Mot Test Centre

Wilson Mot Test Centre We are an independent vehicle service centre, with over 50 years experience in the motor trade.

Offering Class 4 MOT tests, Servicing, Air-conditioning, Electrical repairs and Diagnostics, including TPMS.

03/09/2026

It's been a few months since our last post. We have been super busy and putting any kind of content together has been a challenge.

However here are a few recent Air Conditioning jobs we've had in.

As this is still something which is very much misunderstood amongst vehicle owners, we would just like to make clear the importance of having the system properly checked and repaired. To save you money and to save the environment.

As we have mentioned in previous posts, there are a lot of people who think that, when the Air-conditioning system doesn't work, it just needs "re-gased".
Some think the A/C button is just for summer weather.
And even more concerning, is the garages and parts stores, willing to just refill an empty system, without checking it for leaks!
I have recently witnessed myself, a major car accessory store filling 2 cars in the car park, with the bottles of stuff off the shelf, whilst the customers stood by and watched.

Not only is this unprofessional, it is against the law to fill a system that is known or suspected to be leaking, as the gas given off from the refrigerant, when released to atmosphere, is harmful to the environment and your lungs.

The bottles of refrigerant they sell also contain sealant, which not only causes A/C system clogging. It also causes a garages A/C service machine to become clogged, costing thousands to repair or replace, when you take your car to be diagnosed, after the parts store refrigerant didn't work.

It is much more effective, environmentally friendly and more cost effective in the long run, to have the system properly checked out by professionals. It's better to know if the system is leaking and get an idea of what it's going to cost to repair, rather than to just pay a cowboy who will fill it, regardless of whether it leaks or not.

In some cases, there could also be a mechanical or electrical fault stopping your A/C system from working, this is also going to be missed by the cowboys, who just regas only.

These two cars we had in recently for A/C work, both had non functional systems.

The Porsche 911 had been "Re-gased" by another garage and had stopped working after a few days.
When checked properly, we found a leak in a high pressure pipe underneath the vehicle, which had rubbed through at a mounting clip.
This is now waiting on a replacement pipe.

The Ford Focus ST A/C system had limited access and required removal of the front bumper, turbo intercooler, active air shutters and vents, to test further for leaks. This was authorized by the customer, before we carried out the work.
When we pressure tested the system, we found a major leak in the condenser.
A new condenser was fitted, before further pressure testing, and once satisfied the system was sealed, we carried out an A/C service, to refill the system with Refrigerant.
The system is now back to working as it should๐Ÿ‘Œ

Remember folks that the Air-conditioning System also works like a dehumidifier, removing moisture from inside the car and clearing windows faster, during colder months with wet weather.

Keeping the system running all year round, helps keep it operational for longer, saving you money. And it keeps your car drier inside and easier to clear windows when it's cold.

Keep that A/C button switched on ๐Ÿ™‚

Thanks for sticking with the story folks, I know it's a bit of a novel, but well done for reading it till the end. โญโญ

If you have air conditioning trouble and want it checked properly, don't hesitate to call us, we will check the system mechanically, electrically and pressure test for leaks.
We DON'T just "re-gas"

Have a good evening folks ๐Ÿ™‚
Stevie.


27/05/2026

Now that the warmer weather is here, many drivers will be reaching for that A/C button. Only to find the system not working, just like one of our recent customers found, with this lovely little Audi.

If you are having car Air-conditioning troubles, give us a call ๐Ÿ˜Ž

17/04/2026

One of this week's jobs on a 2010 Honda Civic

This one had been for an MOT test at another garage, failing on an Antilock Brake System malfunction.

The other garage, had diagnosed this as a faulty A.B.S. module. However, the customer wanted a second opinion and brought the car to us.

We are so glad that they did, because we have saved them from spending hundreds of pounds on a miss diagnosis.

We diagnosed a faulty wheel speed sensor causing the problem.
We then fitted a good quality replacement and confirmed the fix! ๐Ÿ™‚




One of this week's jobs on a little Hyundai i20. The issue with this one, was a brake pedal pulse and strange grating no...
22/11/2025

One of this week's jobs on a little Hyundai i20.
The issue with this one, was a brake pedal pulse and strange grating noise, when braking.
Our experience told us this issue, was most likely caused by an Anti-lock Brake System fault.

The Anti-lock Brake System (ABS), is designed to release brake pressure to any wheel that is detected to be at a lower speed than the rest (Skidding) when braking. Then, once the wheel speed matches the rest, the brake pressure is reapplied. This operation is continuous and happens faster than you can blink.
This results in a pulsation being felt in the brake pedal, as the brake pressure is continuously changed, during a wheel lock event (Skidding).

By using sensors and tone rings with a number of teeth or magnetic segments, at each wheel. The Anti-lock Brake System, can monitor all the road wheel speeds and compare them to each other, whilst also using pre programmed data, for various different rotating speeds, due to changing steering angles.
And by using a series of electronic valves, to control the pressure of brake fluid, being sent to each of the brakes. The system can quickly overcome a wheel locking up, due to skidding, by rapidly opening and closing these valves, as required and in relation to the data from the wheel speed sensors, which are reporting the lower road wheel speeds.

As the Anti-lock Brake System is just doing it's job, it doesn't think anything is wrong. This meant, that there were no warning lights or any fault codes stored.
However, this vehicle, was clearly doing something that wasn't normal, as noticed by our customer.

This type of issue usually happens at slow speeds, when approaching junctions or roundabouts. And can be caused, by failing sensors, higher resistance in a sensor circuit, or a deteriorated or broken wheel speed tone ring.

We used the scan tool, to monitor the wheel speed data on road test, this confirmed an issue with the left front wheel speed signal. And on closer inspection, we found that the left front wheel speed tone ring, was broken.

We fitted a replacement tone ring and then carried out a second road test, confirming the fix.
No more pedal pulsing.๐Ÿ‘Œ

Thanks for reading till the end
Have a good weekend folks ๐Ÿ™‚

Stevie.

18/10/2025

Another one of this week's jobs, on a lovely Nissan X trail.

This one had a stop start malfunction and engine management light on.

We diagnosed this one, as having a restricted Diesel Particulate Filter. Which resulted, in excessive exhaust back pressure, and soot content levels outside the range for the vehicle, to do it's own dynamic regeneration of the DPF, in order to clear the blockage.

This can happen because of engine management faults, or in most cases, because of constantly doing short journeys, where the exhaust temperatures necessary to burn off soot during a dynamic regeneration, are never reached. Or because the regeneration process is interrupted, by turning off the engine, or by stop start driving.
Typically, the exhaust temperature generated in the DPF, needs to be around 600ยฐc for an extended period of 20-30 minutes, in order for the engine management system, to complete a successful regeneration and burn off the excess soot content.
It does this, by using fuel, either sprayed into the exhaust by injecting on the exhaust stroke in the engine cycle. Or by using a separate injector, mounted in the exhaust, to spray fuel directly in front of the DPF.

There was no way for this vehicle to do it's own regeneration, since the soot level was too high.
We carried out a DPF clean, to clear the soot build up. Then rechecked the exhaust pressure, to confirm the repair. ๐Ÿ‘Œ๐Ÿ™‚

18/10/2025

One of this week's jobs on a lovely BMW 520d ๐Ÿ™‚
This one had a few warnings displayed, for a pedestrian protection system malfunction.

The pedestrian protection system, can range from camera or radar activated warnings or emergency braking, when pedestrians or objects are detected in the vehicles path.

It can also include features to limit collision forces to pedestrians, by using pyrotechnic modules, within the bonnet hinges and catches, which fire when a pedestrian collides with the front of the vehicle. This allows the bonnet to pop up and act to deflect the pedestrian up over the windscreen, as opposed to through it. It also provides extra space between the bonnet and engine, acting as a crumple zone to soften the impact.

The issue on this BMW was a circuit malfunction, with one of the pyrotechnic modules, on the right hand bonnet catch.

On inspection, we found that the problem was caused by an improper repair, previously done on the wiring harness.

The wiring, had been joined by crimp and seal connectors, which were neither crimped properly, or sealed with heat. This would have given a more solid grip on the insulation, whilst protecting the connection from moisture and dirt.
Instead, the connection had been left exposed. And if that wasn't bad enough, the wiring had been incorrectly routed and was fouling the metal bracket, for the bonnet catch! ๐Ÿ™ˆ

We removed the entire catch assembly, with the pyrotechnic module, then repaired the wiring.
We also used crimp and seal connectors, which were properly crimped. We also used some extra pieces of shrink tubing, to ensure a tighter seal, once the connectors were heated and sealed, since the wiring insulation isn't all that thick.
We then used harness tape, to provide extra protection to the wiring. And once the catch assembly was back in place, we routed the wiring harness the way it should have been, avoiding any fouling.

We cleared the fault codes, then made sure, that there were no more warning lights and no faults returned. ๐Ÿ‘Œ

07/09/2025

Here is one of our jobs from a few weeks ago, on a Vauxhall Vivaro.
The customer complaint with this one was a charging malfunction warning on the instrument panel.

We confirmed the malfunction warning, before doing a full diagnostic scan, where we discovered a fault in the Universal Power Control module, relating to an invalid Alternator link.

The Alternator, is the component which is responsible, for charging the vehicle's battery and providing power for all electrical components, when the engine is running.

Conventionally, the Alternator would have a constant output voltage of around 14 volts, regardless of the power demanded from vehicle electric systems.
This leads to inefficient charging, added wear on the Alternator and unnecessary load on the engine, which reduces fuel economy.

This vehicle, uses what is known as a smart charge system. And is the modern way of providing power for vehicle electrical systems and charging the battery.

The smart charge system, only supplies an output voltage, when the battery voltage falls below 12.5 volts, or the load on the battery is extremely high.
An example of this would be on a cold winter morning, when the heater is turned up, the lights, screen demister and heated seats etc. are all on. In this scenario, the battery voltage will drop quickly, so the smart charge system will output an increasing voltage, to increase the charging rate of the battery.

The output voltage can, in some cases reach around 18 volts, if the vehicle battery is extremely low on charge. For this reason, it is advisable, that modern vehicle's are not jump started, when they have a flat battery. The reason being, that many electrical components on the vehicle, are not designed to work with these higher voltages, which can damage them.

The smart charge system utilises regenerative charging, where it will output a higher voltage and increase charging rate, during vehicle braking and slowing down, such as when approaching a roundabout.
This creates a more efficient charging system and increases fuel economy, since there isn't an unnecessary load on the engine, during normal use.

The system is controlled via a Local Interconnect Network (computer communication) between the Alternator and another module, typically either an Engine Control Module, or a Body Control Module.

In the case of this Vauxhall Vivaro (also the same vehicle as a Renault Trafic), the Alternator shares communication, with the Universal Power Control module, this is a computerised fusebox, in the engine compartment.
The information, is then relayed on, to the Engine Control Module, which uses inputs and information from other systems, to control the charging operation and the rates of charge, of the Alternator, via the LIN communication signals.

In this scenario, the LIN communication was either missing or being corrupted, causing the malfunction warning and forcing the Alternator, in to a fixed charge rate mode.

We carried out an oscilloscope test on the Alternator LIN communication circuit, and found, that the network was displaying corrupted signals and intermittent short circuit to ground (negative).

When the Alternator was disconnected from the network, the corrupted signals and shorts disappeared, proving the fault was internal to the Alternator.

We replaced the Alternator and then confirmed the fix, using the oscilloscope. We then used the scan tools vehicle voltage display, to check the operation of the system and to make sure, that there were no more charging faults reported.๐Ÿ‘Œ

The video shows the oscilloscope patterns, with and without the Alternator being connected. And a closer look at a valid signal (data packet) after the repair.

Thanks for reading till the end, I know it's a lot to take in, but now you know how the system functions. ๐Ÿ˜‰

Happy Sunday folks.

Stevie

16/08/2025

Here is one of this week's jobs, on a lovely little Volkswagen Polo.

The customer complaint with this one, was that the Air Conditioning wasn't working.

We diagnosed this one, as a faulty interior blower speed controller.
The issue was, that the blower didnt work on the first speed setting. This meant that there was no airflow over the evaporator inside the car, resulting in freezing of the evaporator core and pipes, which restricted the refrigerant flow around the system, as shown in the video.

The system was then shutting down the compressor, in order to prevent further freezing and damage.
However when speed setting two was selected, we can see that operating conditions are restored.

This one just needs a new blower speed controller and it will be perfect. But in the meantime, we advised the customer to use the other 3 speeds as required.

Thanks for watching
Have a lovely weekend folks!๐Ÿ˜€

Hi everyone, Just a wee reminder we are still away on holiday but re open Monday 7th of July Katieโ€™s 40th birthday ๐Ÿคซ๐ŸคฃLoo...
03/07/2025

Hi everyone, Just a wee reminder we are still away on holiday but re open Monday 7th of July Katieโ€™s 40th birthday ๐Ÿคซ๐Ÿคฃ
Looking forward to seeing you all when we get back.

Think this will be this year's winner for dirtiest cabin filter! ๐Ÿคข๐Ÿคฃ
12/06/2025

Think this will be this year's winner for dirtiest cabin filter! ๐Ÿคข๐Ÿคฃ

Address

Unit 3 Canal Yard, Glen Village
Falkirk
FK12BE

Opening Hours

Monday 8am - 5pm
Tuesday 8am - 5pm
Wednesday 8am - 5pm
Thursday 8am - 5pm
Friday 8am - 5pm
Saturday 8am - 12pm

Telephone

+441324633406

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