Lennox Heat Pump Service Nationwide

Lennox Heat Pump Service: The Marietta Owner’s Guide

Lennox heat pump service in Marietta typically runs $150 to $650 for most common repairs, with parts like defrost control boards, contactors, and capacitors usually in the $180 to $380 range installed. We stock Lennox-compatible service parts on our trucks, and in most cases we can have your system diagnosed and repaired the same day you call. Most homeowners discover a failing part in one of two ways: the outdoor unit runs but the air from the vents never gets warm in winter, or the system short-cycles on and off every few minutes in summer. Either way, the fix usually comes down to one specific component, and knowing which one saves you time and money.

Call (478) 662-5175

Which Lennox Models This Applies To

We service the full Lennox heat pump lineup sold in Cobb County: the Merit series (ML14XP1, ML16XP1), the Elite series (XP14, XP16, XP20, XP21), and the premium Signature series (XP25, SL25XPV). Each series uses different control boards, sensors, and drive components, and they are not interchangeable. The fastest way to identify what you have is to look at the data plate on the side of the outdoor unit. The model number starts with a letter code, and the first two digits after the model prefix tell you the series and nominal tonnage. That plate matters more than your thermostat or the indoor air handler nameplate when we are matching a part.

One compatibility gotcha we see often in Marietta: older Lennox systems from the early 2000s, especially the HP29 and HPXA series, use obsolete defrost control boards that Lennox no longer manufactures. When that board fails, a generic universal board will not communicate correctly with the existing thermostat wiring. We keep quality aftermarket equivalents for these legacy boards that match the original wiring pinout exactly. On newer systems, we generally recommend genuine Lennox OEM parts while the equipment is under warranty, because using an aftermarket part can void the compressor warranty. Once the system is out of warranty, we will present the OEM price alongside a reputable aftermarket option and let you choose based on the lifespan you want. We are an independent service provider and not affiliated with Lennox, which means we have no incentive to push one path over the other.

Signs Your Lennox Heat Pump Service Is Failing

• Outdoor unit runs but air is lukewarm in winter. This usually points to a failed reversing valve coil or a defrost control board that has stopped sending the signal to switch between heating and cooling modes. The compressor is working, but the system is stuck in the wrong mode.
• System short-cycles every 5 to 10 minutes. A failing capacitor or a refrigerant pressure switch that is tripping under load will shut the unit down early. In Marietta’s clay-heavy soil, a compression-worn contactor from vibration is a common culprit, especially on units mounted on side yards with poor drainage and shifting pads.
• Outdoor coil ices over and never defrosts. On Lennox units, this is almost always the defrost thermostat or the defrost control board. Georgia winters with mid-40s temperatures and high humidity create exactly the conditions where defrost cycles happen constantly, and a weak board will fail faster here than in drier climates.
• You hear a loud hum or click at startup, then nothing. That is typically the compressor contactor failing to pull in fully, or a capacitor that has lost its rated microfarad value. A weak capacitor will hum, then trip a thermal overload, and the unit goes silent until it cools down and tries again.
• Thermostat says the system is running but the outdoor unit never turns on. This points to a failed high-pressure or low-pressure safety switch, or a broken control wire between the air handler and the outdoor unit. We trace the 24-volt control circuit first, because replacing the wrong part here costs you money for nothing.

Replacement Cost & What’s Included

Here is what you can expect to pay in the Marietta area when we replace common Lennox heat pump service parts. These are installed prices, parts and labor included, with a written quote before any work begins:

• Capacitor replacement: $150 – $300
• Contactor replacement: $150 – $280
• Defrost control board replacement (OEM): $280 – $420
• Defrost thermostat replacement: $150 – $280
• Reversing valve coil replacement: $150 – $260
• Refrigerant pressure switch replacement: $180 – $350
• Full reversing valve replacement: $450 – $650
• Compressor replacement: $1,200 – $2,800 (quoted on inspection)

What drives the range is part availability, system age, and whether the repair requires recovering and recharging refrigerant. Every repair we do includes a written guarantee that spells out exactly what is covered and for how long. If that same repair fails during the guarantee period, we return at no charge under the 365-Day Done Right Promise. No fine print, no argument.

DIY or Call Us?

There are things you can safely check before calling. Confirm the thermostat batteries are fresh, the filter at the air handler is not clogged, and the breakers at the panel are not tripped. Those three checks cost nothing and genuinely solve a share of no-start calls we get in Marietta. What you should not do is open the outdoor unit cabinet to test a capacitor or contactor. A capacitor holds a charge even after the power is off, and the unit operates at 240 volts. That voltage can stop a heart. If the outdoor unit is not running and the basics check out, call (478) 662-5175 and we will send a technician with the parts already on the truck. You will know who is coming before they arrive, by name and photo, and they will show a badge at the door.

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