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Get your free estimateDaikin Heat Pump Service: The Marietta Owner’s Guide
Daikin heat pump service in Marietta typically runs $150 – $650 for a repair, and most jobs are diagnosed and fixed the same visit. If your Daikin unit is blowing hot air in cooling mode, short-cycling, or running nonstop without reaching temperature, the most common culprits are the reversing valve, defrost control board, thermistors, or a refrigerant leak at an indoor coil fitting. We keep Daikin-compatible reversing valves, defrost boards, and sensor kits stocked on our trucks across Marietta because these are the parts that fail first on our humid Georgia days.
Victor Mancini has been working on Daikin equipment since the brand went mainstream in the Southeast, and the pattern is consistent: the compressor outlives the controls around it. What owners notice is a unit that suddenly sounds different, runs longer than it should, or ices up at the coil when it has no business doing so. The fix is rarely a full system replacement. It is usually one failed part, replaced cleanly, with the price handed to you in writing before we open a single panel.
Which Daikin Models This Applies To
Our service covers the residential Daikin lines most common in Marietta homes: the DX series (DX16TC, DX18TC, DX20VC variable-speed), the newer FIT systems (DZ17VSA), and the Daikin Comfort and Daikin One communicating platforms. If you have a Goodman-badged Daikin product, the internal specifications are largely the same by design, so the parts compatibility carries over.
The gotcha with Daikin specificity is that the communicating controls do not cheerfully accept generic substitutes. A Daikin FIT air handler, for example, wants a Daikin or approved Daikin-matching thermistor with the correct resistance curve, not a universal sensor we crimped to fit. We stock OEM Daikin parts where the control logic demands them, and we use quality aftermarket equivalents only where the part is mechanical rather than electronic, things like capacitor kits, contactors, and fan blades. Your model number is on a data plate inside the outdoor unit and on the air handler cabinet. Photograph it before you call, and we can confirm part availability for your exact Daikin model before we even roll the truck. That saves you a second visit and a second service window.
Styles & brands we work with







Signs Your Daikin Heat Pump Service Is Failing
- Unit runs in cooling mode but blows warm air. This almost always points to a stuck reversing valve or a failed defrost control board. The valve is what lets a heat pump switch between heating and cooling, and when it seizes partway, you get lukewarm air in both seasons.
- Outdoor coil ices over on a mild Marietta afternoon. A defrost thermistor or defrost board failure prevents the unit from clearing frost. Left alone, the ice builds until it crushes coil fins and starves airflow.
- Compressor short-cycles, then locks out. A failing run capacitor or a misreading discharge-line thermistor can cause the board to cut power prematurely. The system tries, trips, waits, tries again, and the house never gets comfortable.
- Electric heat strips run even when the heat pump could handle the load. The outdoor unit’s sensor suite may be misreporting temperature, which forces the system into auxiliary heat. Your power bill in Marietta will tell you within one month that something is off.
- You hear a chattering or buzzing from the outdoor unit, then silence. On Daikin FIT units especially, a failing inverter board or contactor presents this way. The compressor itself may be fine; the control layer is what quit.
See the difference
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After
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AfterReplacement Cost & What’s Included
Here is what we tell Marietta homeowners before we touch a screwdriver. A defrost control board replacement typically lands between $280 and $520, parts and labor. A reversing valve job runs $450 – $650 because it requires recovering refrigerant, brazing the new valve in place, pulling a vacuum, and recharging. Thermistor replacements are usually $150 – $280 depending on access. A run capacitor or contactor swap is the least expensive fix, generally $150 – $250.
| Part | Installed Price Range (Marietta) |
|---|---|
| Defrost control board | $280 – $520 |
| Reversing valve | $450 – $650 |
| Thermistor / temperature sensor | $150 – $280 |
| Run capacitor or contactor | $150 – $250 |
| Diagnostic-only visit (if no repair performed) | Often waived when repair proceeds; call for current policy |
Every Daikin repair we do in Marietta carries the 365-Day Done Right Promise. That is a written guarantee we hand you before we leave. If the same part fails inside a year, we come back and fix it at no charge. No fine print, no prorated nonsense, and we are the only company we know of in Cobb County that puts that guarantee on paper for every single repair.
DIY or Call Us?
Electrical work on a heat pump is genuinely dangerous. These units carry 240 volts, and Daikin inverter boards hold stored charge even after the disconnect is pulled. Victor will tell you plainly: do not open the outdoor cabinet and start probing if you are not trained for it. The stored capacitor charge alone can knock a grown man off his feet.
What you can safely do: check that your thermostat is calling for the right mode, confirm the outdoor disconnect and indoor breaker are not tripped, and check for ice buildup on the outdoor coil which you can photograph and describe to us. After that, call (762) 240-5599 and talk to a live person, day or night. We will ask what the system is doing and get a technician out with the right Daikin-matched part in the truck. Tell me what the system is doing, and I will tell you exactly what it needs, no guesswork, no runaround.
FAQs
We typically see 8 to 12 years from the factory sensor suite in the Marietta climate, but the outdoor thermistors on the discharge line run hotter and fail sooner. Humidity and our frequent short-cycling in shoulder seasons accelerate sensor drift. If your unit is past its tenth summer, a sensor failure is not a fluke, it is on schedule.
A reversing valve is always replaced, never repaired internally. The internal slide seizes or the valve body leaks, and no amount of tapping frees it reliably. We do the replacement correctly with a nitrogen purge during brazing to keep scale out of the system.
Most board, thermistor, and capacitor replacements are done in 60 to 90 minutes. A reversing valve is a half-day job because of the refrigerant recovery and vacuum process. We do not rush that one, because a sloppy vacuum is what ruins a new valve inside six months.
We stock the most common Daikin failure parts on our trucks in Marietta: defrost boards, thermistors, capacitors, contactors, and fan motors. For less common components we source from our local Atlanta distributor, usually same-day. We will confirm part availability for your specific model number before we schedule the service window. Call (762) 240-5599 for an exact quote, and you will have a written price before any work begins.
Written by Victor Mancini, Owner, Cold Harbour Heating and Air Marietta at Cold Harbour Heating and Air Marietta, serving Marietta and nearby areas.