By Peter Coll. HFO-1234yf, a new replacement for R-134a, is a non-environmental impact refrigerant with a decreased atmospheric lifetime. Learn what it is, why we're changing refrigerants, what the differences are, whether or not your shop will need new equipment, and more, in this question-and-answer session with Peter Coll from Neutronics.

By Scott 'Gonzo' Weaver. Leave it to the manufacturers to take a simple thing like heat and air conditioning and turn it into an electronic jungle of wiring, sensors, and computer components. HVAC units have come a long way from when I started in the business. Not that I want to dwell on the past, but it might be a good idea to make sure we understand the basics before diving into the problem of today’s systems. I always feel that if I understand a system fully before doing any repair work I’m more likely to get it right the first time.

By Gary Goms. Although diagnosing misfires can be a tough assignment for any driveability technician, the diagnosis can be made much simpler if he understands the basics of misfire diagnosis. For example, when the first OBD II misfire monitor was first introduced in 1996, technicians were puzzled by problems with false misfire diagnostic trouble codes (DTCs). Case in point, vehicles being driven on washboard dirt roads began recording false misfires.

By Joe Glassford. Accuracy of: Plus or minus 0.1% is Best. Check the owner’s manual for your meter under DC accuracy.

By Carlton Banks. Many modern-day fuel systems offer a new look into system status definitions. It's become very important to extend our understanding well beyond the concepts of simple "open loop" and "closed loop" status. This month, we will explore the new fuel system definitions that are present on many of today's vehicles. We'll begin our discussion by looking at each one on an individual basis.

By Scott 'Gonzo' Weaver. Some male patrons tend to want to “talk to the mechanic” verses talking to the front-desk person. Especially if that person is female. In my case, the front desk person is my daughter. She has seen it all and is very knowledgeable, I might add. Ask her a car question, any question, and she’ll have an answer for you.