Vehicle AC Repair

Steve Cusson
Steve Cusson

Steve is the owner of Phobia Auto Care. Steve has been a mechanic for 8 years now and just like any mechanic he started from the bottom. He worked at multiple places like Canada West Truck Center and then moved over to Cummins Western Canada.

We are here to talk about air conditioning today and educate you on why AC is so expensive to repair and diagnose, as well as the different components of an AC system.

Vehicle AC systems are not so simple anymore. They’re all computer-controlled, and if all the sensors aren’t happy, then the ECU won’t turn the compressor on.

What is an ECU?

ECU stands for Engine Control Unit.

There’s lots of different components in an AC system, and they all have to work together for the air conditioning to work. It is a sealed system, so if it is low on charge, that means there’s a leak somewhere. There are various tools to detect a leak, including the scan tool, which for almost every new vehicle we have to hook up to diagnose an AC system.

We’ll start with the HVAC control.  These your AC buttons, which has the computer tell the compressor to turn on if the pressure is okay. The compressor is what pumps the refrigerant through the whole system.

Your condenser is mounted in front of the vehicle, and the cold air rushes through it. Your fans turn on to bring the pressure down, and air rushes through the evaporator (in your dash) which cools the air down.

There is an accumulator, and you’ve got a couple pressure fittings for hooking up our equipment. Any one of these joints in this closed AC system can leak refrigerant which will cause everything to stop working. We can have electrical wiring issues, we can have control module issues… there’s a lot of different items in the system that can potentially cause a failure if they are not properly maintained.

Every function of your vehicle requires an intricate system of many moving parts, working together in cohesion.

Servicing these AC systems isn’t as easy as going to Canadian Tire and buying an R-134 cap, putting it on and charging it. It’s actually the opposite. That stuff will contaminate your whole system!

To properly do it you have to hook up a specific machine. You create a vacuum and make sure this system holds a vacuum. If it doesn’t, you have to find the leak. So, you start by hooking a nitrogen bottle up to it and finding where the leak is in this system in your vehicle.

If you have your vehicle serviced by somebody who doesn’t know what they’re doing, you can actually overcharge a system, damage components and not have cold air blowing on you.

During normal AC operation, especially on a hot day, you’ll notice a puddle of water underneath your vehicle. This is normal. There is a drain in the bottom of the air box that takes all the extra moisture and drains it out, and you’ll see a puddle on the ground.

At Phobia Auto Repair, we have a nitrogen tank which we used to charge AC systems so that we don’t waste refrigerant or vent it into the atmosphere. We use our nitrogen to charge the system to check for leaks so that we’re not releasing r134 into the atmosphere.

But wait: but why are we using nitrogen, and not compressed air to fix car AC systems?

Nitrogen is a dry gas and won’t contaminate the system. It is safe to release into the atmosphere.

We also have dye, which helps us find the pinhole leaks. We have our old trusty 134a machine, and we have our brand new 1 2 3 4 YF machine.

At Phobia Auto Repair, we have five refrigerant certified technicians. As you can see, air conditioning is a complex system. It’s not always as easy as just recharging it and going. If you don’t know what you’re doing, you can wreck a component, you could ruin the system, or you can contaminate it. If it’s too hot outside and your AC’s not cooling you down, come down to Phobia and let us cool you down!