[Skip to Content]

A/C Efficiency Declining?

By on May 1, 2017
condsection

Act Quickly to Avoid Catastrophic Failure

Air conditioning is a wonderful system to have in your truck. It could be very easy to just ride down the road and enjoy the cool breeze flowing from your dash vents, without ever thinking how critical it is to maintain the system, especially, if you drive a newer model truck. The newer A/C systems require much less refrigerant, creating a situation where any leak or defect can quickly become catastrophic!

Just 15 or 20 years ago, many trucks typically had five to eight pounds of refrigerant circulating in the A/C system. Today, most trucks have less than four pounds, and the volume will continue decreasing. Truck manufacturers have made A/C systems more efficient by redesigning the heat exchangers. That’s a term that may not be very familiar to you, but it’s critical to understanding how an A/C system operates and knowing how to diagnose a problem when one arises.

Higher Condenser Efficiencies

Let’s start with the condenser, the most visible heat exchanger. In most cases, it is located under the hood in front of the radiator. The condenser fins are the ones you see if you look just behind the grill of your truck. The condenser removes the heat that the refrigerant absorbs as it travels inside the dash of your truck. The heat inside your cab absorbed by the refrigerant flows back through the condenser; then dissipates into the atmosphere via the tubes and fins.

This is why your engine fan cycles more frequently when you turn on your A/C. The engine fan pulls air across the condenser to help remove the heat. One major way truck manufacturers reduced the amount of refrigerant was by changing the condenser tubes from a serpentine flow to a parallel flow. Several tiny tubes stacked together in rows have now replaced the large continuous tube that previously ran back and forth through the condenser. This new design allows a 25% improvement in heat transfer with almost 50% less refrigerant.

The A/C Cycle of Life

Located inside your cab behind the dash on the passenger side, the evaporator is the second important heat exchanger. It uses the cold refrigerant that flows through it to absorb the heat inside the cab for routing to the condenser. That is what you might call the A/C cycle of life. Most evaporators have also gone through the same design metamorphosis as the condenser. More efficient, parallel flow evaporator cores have also replaced the serpentine tube design.

Because of the refrigerant’s lubricating properties, it’s critical to understand that a leak anywhere in the A/C system must be repaired ASAP. Because very little refrigerant is needed to make modern systems operate efficiently, a small leak can allow the A/C compressor to overheat and seize up, due to a lack of cool refrigerant and oil flowing back to the compressor from the evaporator. A compressor can be destroyed in a very short period of time, resulting in a very large expense.

So, if you notice any decline in the performance of your A/C system, shut it down and have it checked at the next TA Truck Service location along your route, before your compressor fails and the loss of the cool breeze coming from the dash dramatically heats up your frustration level.

About Road King

For the professional Driver

Leave a Reply

Your email address will not be published. Required fields are marked *