Why Is My Electric Bill So High This Summer? (Forney, TX Homeowners Guide)
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If your electric bill jumped $80, $150, or more compared to last summer, your air conditioner is almost certainly the reason. In Forney and across Kaufman County, HVAC systems account for 50 to 70 percent of total home electricity use during the summer months. When something is wrong with the system, or when the system is aging out of efficiency, it shows up directly on your Oncor bill before it shows up as a comfort problem.
This guide walks through the most common reasons HVAC systems drive up electricity costs in North Texas, how to tell whether you have a fixable problem or an efficiency problem that warrants replacement, and what you can do about it today.
What a Normal Summer Electric Bill Looks Like in Forney
Forney homeowners in the Oncor service territory (which covers most of Kaufman County) should expect electric bills in the following ranges during peak cooling months (June through August), assuming the AC is working efficiently:
- 1,200 to 1,500 sq ft home: $150 to $220 per month
- 1,500 to 2,000 sq ft home: $200 to $290 per month
- 2,000 to 2,500 sq ft home: $250 to $380 per month
- 2,500 sq ft and above: $350 to $500+ per month
These ranges assume a system with a SEER rating of 14 or above, good duct condition, and standard insulation. If your bill is running significantly above these ranges for your home size, the AC system is the most likely explanation. A bill that is 25 to 40 percent higher than last summer with no change in usage habits almost always points to a system efficiency problem.
The Most Common Reasons Your AC Is Driving Up Your Bill
1. A Dirty or Clogged Air Filter
This is the most common cause of a sudden efficiency drop and the easiest to fix. When the air filter is clogged, the system has to work harder to pull air through it. The blower runs longer to move the same amount of air. Electricity use climbs while cooling output drops. A severely restricted filter can increase energy use by 10 to 15 percent.
Check your filter now. If it has been more than 30 days since you changed it, replace it before anything else. During a Texas summer, filters need to be changed every 30 days in most homes, especially those with pets.
2. A Low Refrigerant Level
Refrigerant does not get consumed in normal operation. If the level is low, there is a leak somewhere in the system. A system running low on refrigerant loses cooling efficiency rapidly. It runs longer cycles trying to reach the set temperature, uses more electricity, and still cannot keep up. The outdoor unit may ice over. Rooms that used to cool evenly may feel uneven.
This is not a DIY fix. Refrigerant requires a licensed HVAC technician to locate the leak, repair it, and recharge the system. If you notice a sudden efficiency drop alongside rooms that are not cooling properly, refrigerant is one of the top suspects.
3. A Failing Capacitor
The capacitor is the component that starts and runs the compressor and fan motors. Capacitors degrade faster in Texas heat than in cooler climates. A failing capacitor causes the compressor to struggle at startup, draw more current than normal, and run less efficiently even when it does manage to start. This increases electricity use without a corresponding increase in cooling output.
Capacitor replacement is one of the most common repairs in North Texas, running $150 to $350 installed. If you notice the system starting slowly, hesitating, or running longer than usual to reach temperature, a capacitor check is worth doing before assuming the problem is something bigger.
4. Dirty Condenser Coils
The outdoor unit (condenser) has to shed heat into the outside air to cool your home. When the coil fins are coated with dirt, pollen, cottonwood, or other debris, heat transfer is reduced. The system runs longer and works harder to move the same amount of heat. This is especially common in Forney and the surrounding Kaufman County area in late spring and early summer after cottonwood and pollen season.
The fix is a professional coil cleaning, typically part of a standard tune-up. You can rinse the exterior of the unit gently with a garden hose from the inside out (not a pressure washer), but a proper coil cleaning with the appropriate chemical cleaner should be done by a technician.
5. Duct Leaks
If the ductwork running through your attic or walls has leaks, you are paying to cool air that never reaches your living space. Duct systems in North Texas homes built before 2000 are particularly prone to this. A system losing 20 to 30 percent of its conditioned air through duct leaks will run 20 to 30 percent longer to compensate.
Signs of significant duct leakage: rooms that never get as cool as the rest of the house, visible dust marks around supply registers, a system that runs constantly without reaching the thermostat set point. A technician can perform a blower door test or duct leakage test to quantify the problem.
6. An Aging, Low-Efficiency System
If your system is 12 to 15 years old and running correctly, your electric bill may still be high simply because the equipment is old. Systems built before 2010 commonly have SEER ratings of 10 to 13. The minimum federal efficiency standard as of 2023 in the South is 15 SEER2. A modern 18 SEER2 system uses roughly 28 percent less electricity than a 13 SEER system for the same amount of cooling.
If you want to see what a more efficient system would save on your monthly bill, use the SEER savings calculator on this site. Enter your current system's SEER rating and the replacement rating, and it calculates the annual and 10-year savings.
How to Diagnose the Problem Before Calling a Contractor
Before calling anyone, a quick self-check can help you narrow down what is happening and give the technician useful information when they arrive.
- Check the air filter. Replace it if it has been more than 30 days or if it looks clogged.
- Look at the outdoor unit. Is the fan running? Is there ice on the refrigerant lines or on the unit itself? Is there debris blocking the coil fins?
- Check the thermostat setting and ensure it is in cooling mode at a set point below the current room temperature.
- Listen for unusual noises. A clicking that does not resolve at startup, a hissing near the outdoor unit, or a buzzing outdoor unit that is not running are all signs of specific problems.
AC Making a Loud Noise? Here's What It Means.
- Note how long the system runs per cycle. A system running 20 to 30 minute cycles with short off periods is working hard. A system that runs continuously is struggling to keep up.
If the AC is running but not cooling effectively alongside the high bill, see the dedicated diagnostic guide.
AC Running But Not Cooling? Start Here.
For a step-by-step symptom-based diagnosis, use the HVAC troubleshooting tool on this site.
Quick Fixes That Can Lower Your Bill Right Now
Some of the fixes for a high summer electric bill cost nothing or very little:
- Replace the air filter (under $15, takes five minutes)
- Set the thermostat to 78 degrees when home and 85 degrees when away. Each degree lower than 78 adds roughly 3 percent to cooling cost.
- Close blinds and curtains on west-facing and south-facing windows during peak afternoon hours (2 pm to 6 pm)
- Make sure all supply and return registers are open and unobstructed by furniture
- Clear debris, plants, and objects away from the outdoor unit. It needs 12 to 18 inches of clearance on all sides for proper airflow.
- Run ceiling fans in occupied rooms. Ceiling fans allow you to raise the thermostat set point by 4 degrees with no change in perceived comfort, reducing cooling load significantly.
These steps will not fix a mechanical problem, but if your system is otherwise working correctly, they can meaningfully reduce monthly bills during peak summer heat.
When the Bill Is Telling You to Replace the System
If your system is more than 12 years old and your summer bills are running $100 or more above what you expect based on your home size, the economics of the situation often favor replacement over continued repair. The rule of thumb HVAC professionals use: if the cost of the needed repair exceeds 50 percent of the cost of a replacement system, replacement is the better financial decision.
Use the price estimator to get a realistic cost range for your situation, whether it is a repair or a full replacement.
For help working through the repair versus replace decision:
Repair or Replace Your AC? How Forney Homeowners Should Decide
Getting a Vetted Contractor to Diagnose the Problem
Most of the issues that drive up summer electric bills require a licensed HVAC technician to diagnose and fix. The free contractor matching tool at ForneyhvacPros.com connects you with a vetted local contractor for your specific situation, usually within an hour.
Every contractor in the network holds an active TDLR license and maintains a Google rating above 4.7 stars. You can verify any contractor's license before they arrive using the free lookup tool.
Verify an HVAC Contractor's Texas License (TDLR)
Find a Vetted HVAC Contractor in Forney. Free, No Obligation.
Frequently Asked Questions
Why did my electric bill suddenly go up this summer?
In Forney and Kaufman County, a sudden summer electric bill increase is almost always related to the AC system. The most common causes are a clogged air filter, a failing capacitor, a refrigerant leak, or dirty condenser coils. Each of these issues causes the system to run longer to achieve the same cooling, increasing electricity use without a corresponding increase in comfort. Start with the air filter. If it has been more than 30 days, replace it first and see if the bill improves.
How much does an AC unit affect your electric bill?
In North Texas during summer, the AC system accounts for 50 to 70 percent of total home electricity use. A system that is losing efficiency from a refrigerant issue, failing components, or simple age can increase that portion significantly. An aging 10 SEER system costs roughly 40 percent more to operate than a modern 16 SEER system doing the same cooling work.
Should I be worried if my AC runs all day in Texas summer?
During extreme heat (above 100 degrees), it is normal for an AC system to run most of the day to maintain the set temperature. What is not normal is a system that runs continuously and still cannot reach the thermostat set point. That indicates the system is undersized, has a refrigerant issue, or has airflow restrictions from duct leaks or a clogged filter. Occasional inability to keep up on the hottest afternoons is common. Consistent inability to reach set temperature is a problem.
What temperature should I set my thermostat in Texas summer to save money?
Energy providers and HVAC professionals typically recommend 78 degrees when you are home and awake, and 85 degrees when away. Each degree below 78 adds approximately 3 percent to your cooling bill. Setting the thermostat to 72 degrees instead of 78 adds roughly 18 percent to cooling costs with no other change. Ceiling fans in occupied rooms allow you to feel comfortable at 78 to 80 degrees when you otherwise would not.
How do I know if my AC is running efficiently?
Compare your current bill to the same month last year. An increase of more than 10 to 15 percent without a change in usage habits or temperatures points to a system efficiency issue. If you do not have last year's bills to compare, use the SEER savings calculator on this site to estimate what your current system's rated efficiency should cost to operate, and compare that to your actual bill. A significant gap between the two usually means a maintenance or repair issue is reducing efficiency.
Is it worth getting a tune-up if my electric bill is high?
Yes, in most cases. A professional tune-up, which includes checking and adjusting refrigerant charge, cleaning coils, and inspecting the capacitor and contactor, addresses the most common causes of efficiency loss. A tune-up in Forney runs $80 to $150. If it reveals and fixes a refrigerant issue, dirty coil, or weak capacitor, the monthly savings on your electric bill can recover that cost within one to two billing cycles.