Ask the Mechanic: The best way to test an air conditioning system

Every week, we take your questions about what is going on under the hood of your vehicle and pose them to a knowledgeable mechanic in the Greater Toronto Area. In today’s column we discuss a broken air condition in a Honda Odyssey and what it could mean if your brake doesn't release.

Dear Ask a Mechanic,

I drive a 2006 Honda Odyssey. The air conditioning worked fine until recently. I’m not sure what happened but I tried turning it on the other day but it just stopped working. I examined the situation further and found my compressor was not engaging. What can I do next? – Feeling hot

Zafar Habib, co-owner of Humble Autohaus in Scarborough, believes there could in a leak in the system and said he’s seen customers with vehicles from this series have problems with the air conditioning compressor relay system. In this situation, given the compressor isn’t engaging, refrigerant could be leaking out of the system. He recommends having a professional take a look. A leak inspection must be performed before the system is refilled. If this initial inspection doesn’t reveal a leak, then the mechanic can perform an evacuation and recharge service. This allows the internal system to be emptied of any refrigerant, air and moisture.

“If it's necessary, then they pressurize the system again and put the dye in the system and do an ultraviolet-light test on it,” he explained.

The UV light causes the dye to fluoresce. Using special coloured glasses, mechanics can then locate any leaks and determine if repair is required.

Dear Ask a Mechanic,

For the last couple weeks, the front passenger’s side brake on my car has been not fully releasing. This is causing the car to drag and shake. I’ve noticed this happens when the engine gets hot. What’s causing this and what should I do? – Can’t catch a break

Habib believes there are two possible reasons for this. The first is the caliper could be sticking. The second reason could be the flex hose, which supplies the brake fluid to the caliper, that may have failed internally. The inner layer can swell or tear, acting like a one-way valve or restriction. “When you apply the brake, the system’s pressure will overcome the restriction, but when it’s released the brake cannot fully disengage,” causing the wheel to drag. Habib suggests taking it to a automotive garage to have them check it out. A mechanic will likely perform a road test before removing the wheel causing the issue and performing an examination.

Ask a Mechanic is written by Nida Zafar, a reporter at The Pointer who grew up in a house full of mechanics in Scarborough, and occasionally poses your questions to her dad or brother. You can send your questions to wheels@thestar.ca. These answers are for informational purposes only. Please consult a certified mechanic before having any work done to your vehicle.