AC Circuit Board Repair & Replacement — Above & Beyond Air Conditioning & Heating
OEM control board replacement after SA lightning strikes, Day & Night and Carrier OEM boards stocked, surge protector installed on every job.
The AC circuit board (sometimes called the control board, defrost board, or integrated furnace control) is the brain of your HVAC system. It sequences the compressor, blower, ignitor, gas valve, and safety switches in the right order at the right time. When it fails, the whole system goes dark or behaves erratically. In San Antonio, lightning surge through the residential grid is the number two cause of board failure we see (after age-related capacitor leakage on board capacitors).
Above & Beyond stocks the most common board models on every truck (Honeywell, ICM, White-Rodgers universal replacements), and we have direct warranty-paperwork relationships with Day & Night, Carrier, American Standard, and Trane for OEM board replacements. Free $89 diagnostic credited back with repair. Written estimate with verbatim parts and labor before any work. 30-day callback warranty on every board replacement.
We are also one of the few SA shops that consistently install whole-house and point-of-use surge protection alongside board replacement, because replacing a $345-$685 board without addressing the root cause sets up the same failure to repeat the next storm season.
Three Ways AC Circuit Boards Fail in San Antonio
Lightning Surge Damage
SA Summer Storm Failure
Heat-Stressed Capacitors
Slow-Build Attic Failure
False-Positive Board Failure
Wiring & Sensor Issues
Failure #1: Lightning Surge Damage (the SA summer storm failure)
San Antonio sits in a heavy summer storm zone. Lightning does not have to strike your house. A strike anywhere in the neighborhood can send a voltage surge through the residential power grid that fries sensitive electronics. The board's surge-prone components are the inrush-protection inductor, the transformer, the relay coils, and the microcontroller. We see waves of board failures after every major SA storm event.
The fix is straightforward (board replacement, $345-$685 parts and labor) but the real fix is preventing the next surge with a $40-$60 point-of-use protector plus a $300-$450 whole-house panel protector. We quote surge protection on every board replacement; most customers approve once we explain the math.
Failure #2: Heat-Stressed Capacitor Leakage (the slow-build attic failure)
75% of SA homes have the air handler installed in the attic. July attic temps regularly hit 130 degrees. The board itself sits inside the air handler cabinet at 110-120 degrees in summer. Surface-mount capacitors on the board have rated lifespans inversely proportional to operating temperature.
At 110 degrees operating temp, board capacitors typically die at 8-12 years instead of the nameplate 15-20. Symptoms: intermittent behavior where the system runs fine for hours then misbehaves, and resetting at the breaker restores normal operation briefly. Repair: board replacement; component-level capacitor replacement is technically possible but not economic on residential boards.
Failure #3: Defrost Board or Float Switch Wiring Issue (the 'looks like board' false-positive)
Roughly 25% of failed board diagnoses we field are actually wiring or sensor failures. A tripped float switch making the board appear unresponsive, a corroded thermostat wire connection making the board appear to ignore the call, a failed outdoor sensor making the board appear to misread temperatures.
These cases are why we run our full diagnostic ($89, credited back with repair) before quoting board replacement. Replacing a perfectly good $345-$685 board because of a $25 wire connector wastes the customer's money.
Our Board Diagnostic and Replacement Process
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A real San Antonio team member answers. We ask whether you have had recent storm activity (lightning surge is the number one SA board failure cause), whether the system was recently working normally, and what specific symptoms you are seeing. That tells us which board (control vs defrost vs outdoor) is most likely involved.
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Text with the tech's name and photo when they are en route. No mystery dispatch.
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Roughly 30-40 minutes on site. We test thermostat 24V output, control transformer secondary voltage, board input and output voltages at each terminal, relay continuity on each output, and sequencing of compressor, blower, and heat strip outputs against the board's status LEDs and blink codes. We rule out wiring, sensors, and float switches before quoting board replacement.
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Verbatim parts and labor. Universal board option vs OEM (when warranty is in play). Surge protection add-on quoted as a separate line item; customer chooses.
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Most universal board replacements finish in 45-75 minutes. OEM boards (when warranty is active) often require the same workflow plus warranty paperwork filing, which we handle. Wiring is documented with photos before and after, every wire labeled and re-connected to the same terminal.
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Point-of-use surge protector at the air handler (24V protection) installed in 15-25 minutes, $40-$60. Whole-house panel protector (requires licensed electrician) referred to a partner electrician.
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Final verification: full heating cycle, full cooling cycle, defrost cycle (heat pumps), blower fan speeds, heat strip sequencing. We log the readings. 30-day callback warranty on the board and surge protection install.
Circuit Board Repair Pricing in San Antonio
Diagnostic: $89 diagnostic fee. Credited back when you approve the repair. $89 if you decline, no pressure, no upsell.
| Universal Board Replacement (Parts + Labor) | Price Range |
|---|---|
| Honeywell ST9120 universal control board | $345 – $485 |
| ICM universal control board | $385 – $525 |
| White-Rodgers universal control board | $385 – $525 |
| Defrost board (heat pump, universal) | $345 – $485 |
| Outdoor temperature sensor | $95 – $165 |
| 24V transformer | $185 – $285 |
| Universal relay (low-voltage) | $145 – $225 |
| OEM Board Replacement (Parts + Labor) | Price Range |
|---|---|
| Carrier OEM control board | $485 – $785 (warranty filing included if applicable) |
| Day & Night OEM control board | $485 – $685 (warranty filing included if applicable) |
| American Standard and Trane OEM control board | $585 – $885 (warranty filing included if applicable) |
| Lennox OEM control board | $585 – $885 |
| Communicating board (Infinity, Observer, ComfortLink, iComfort) | $685 – $1,185 |
| Surge Protection (Add-On) | Price Range |
|---|---|
| Point-of-use surge protector at air handler (24V) | $45 – $65 |
| Outdoor disconnect surge protector | $65 – $95 |
| Whole-house panel protector (referred to licensed electrician) | $300 – $450 typical |
| Surge protection install on existing failed-board replacement | -$15 bundled discount |
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Above & Beyond Board Service vs. National HVAC Chains
| Feature | Above & Beyond | National HVAC Chains |
|---|---|---|
| Diagnostic Approach | Full sequencing test, rule out wiring, sensors, float switches before board quote | Often jump straight to board replacement quote |
| Surge Protection on Quote | Always included as a line item, addresses root cause | Rarely mentioned |
| Universal vs OEM Choice | Both stocked, recommended based on warranty status | Often only OEM offered (higher margin) |
| Warranty Filing for OEM | We file Day & Night, Carrier, American Standard, Trane warranty claims | Often left to homeowner to chase |
| Diagnostic Pricing | $89 credited back when you approve the repair | $89 to $149 charged upfront, often not refundable |
| Estimate Format | Written estimate with verbatim parts and labor | Verbal estimates, change orders common |
| Communicating Board Tools | Field tools for Day & Night Observer, Carrier Infinity, ComfortLink, iComfort | Often refer-out for communicating system diagnostics |
| Documentation | Photos of wiring before and after, every wire labeled | Often not done |
| Technician Compensation | Hourly and completion pay, no commission pressure | Commission-driven, techs paid percentage of what you spend |
| Warranty on Repair | 30-day callback warranty included | Often 7 to 14 days, sometimes nothing |
Frequently Asked Questions
How much does an AC circuit board replacement cost in San Antonio?
Universal control boards run $345-$525 parts and labor. OEM boards (Day & Night, Carrier, American Standard, Trane) run $485-$885. Communicating boards (Infinity, Observer, ComfortLink, iComfort) run $685-$1,185. The $89 diagnostic is credited back with repair.
Why does my AC need a new control board after a thunderstorm?
Lightning surge damage is the number two cause of AC board failure in San Antonio (after age-related capacitor leakage). A lightning strike does not have to hit your house. A strike anywhere in the neighborhood can send a voltage surge through the residential power grid that fries the board's sensitive electronics. We install a $40-$60 point-of-use surge protector with every board replacement to prevent the same failure next storm season.
Why did the other shop quote me a $785 board when you found a $185 fix?
Roughly 25% of failed board diagnoses are actually wiring, sensor, or float switch issues that mimic board failure. Replacing a perfectly good board because of a $25 wire connector or a $185 drain clearing wastes the customer's money. We run our full diagnostic before quoting board replacement, which catches the misdiagnosis cases.
Should I get a universal board or an OEM board?
Default: universal board (20-40% cheaper than OEM, same quality, fits every major brand). Exception: if your AC is still under manufacturer parts warranty and the failed board is covered, OEM is the right call. You pay only labor and the manufacturer covers the part. We verify warranty status before quoting and file the warranty paperwork on Day & Night, Carrier, American Standard, and Trane systems.
Do you handle communicating system boards (Carrier Infinity, Day & Night Observer)?
Yes. We carry the manufacturer-specific service tools for all four major communicating control systems: Day & Night Observer, Carrier Infinity, American Standard and Trane ComfortLink, and Lennox iComfort, plus Goodman ComfortBridge. We can read live bus data, verify communication faults vs component failures, and replace boards with the warranty filing intact.
Ready to Book Your AC Maintenance? Call Above & Beyond Today
A real San Antonio team member answers, never a phone tree. Free written estimate before any work. TDLR Class A licensed, $20M general liability, 30 years in the SA trade.
(210) 897-8658
Same-Day Capacitor Replacement
Monday through Friday: 7:00 AM to 7:00 PM | Saturday: 8:00 AM to 5:00 PM | Sunday: Emergency Dispatch Only | After-Hours Emergencies: 24/7, call (210) 837-1466