How a Struggling Vehicle’s A/C System is Costing You More at the Gas Pump

Bob Cornwall • May 6, 2026

Gas prices in the Pomona area are not getting any friendlier, and if you are watching every dollar you spend to keep your car on the road, here is something worth paying attention to. Your air conditioning system has a direct impact on your fuel economy, and when that system is not working efficiently, you are paying for it every single time you fill up. Most drivers never make that connection, but we see the evidence of it constantly in our shop.

Running your A/C is never completely free in terms of fuel. The compressor puts a mechanical load on your engine, and your engine burns more fuel to compensate. That is just how the system works. But a healthy, properly maintained A/C system manages that load efficiently. A system that is low on refrigerant, has a struggling compressor, or is working harder than it should be due to deferred maintenance burns significantly more fuel to deliver the same amount of cooling, or in many cases, less cooling.

If you are commuting down Garey Avenue or sitting in traffic on the 10 freeway to Los Angeles with the A/C maxed out, a poorly functioning system is quietly draining your tank faster than you realize.

The Connection Between A/C Efficiency and Fuel Economy

Your engine drives the A/C compressor through a belt. When the compressor engages, it draws power from the engine. That power has to come from somewhere, and it comes from fuel combustion. Studies have shown that running the A/C can reduce fuel economy by anywhere from 5 to 25 percent depending on the vehicle, the driving conditions, and the condition of the A/C system itself.

That range matters. A well-maintained A/C system operating at peak efficiency sits at the lower end of that impact. A system that is low on refrigerant, forcing the compressor to cycle more frequently and work harder to produce adequate cooling, can push toward the higher end. On a vehicle that gets 25 miles per gallon, losing 25 percent efficiency means you are effectively getting closer to 18 or 19 miles per gallon every time the A/C is running hard.

Over the course of a week of commuting around Pomona, driving out to the Pomona Fairplex area, or making runs up the 71 toward Chino, that adds up to real money out of your pocket.

How to Get Your Efficiency Back

The fix starts with a proper A/C system inspection. We check refrigerant levels, assess compressor function, inspect the condenser and evaporator, and test overall system performance. In many cases, correcting a low refrigerant charge and addressing a minor issue is all it takes to bring the system back to efficient operation.

Replacing a clogged cabin air filter is a quick, inexpensive step that improves both cooling performance and system efficiency. We recommend checking it at every oil change interval.

When your A/C is running the way it should, the load on your engine is managed properly and your fuel economy reflects that. For budget-conscious drivers in Pomona, keeping that system in good shape is one of the smarter investments you can make.