2. When You Need It
Call American HVAC Pros when a heat pump is doing something it should not, in either season. Four situations come up most often. Each one tells the technician what must be separated before any part is replaced.
Ice builds up on the outdoor unit in winter. A light frost that clears during a defrost cycle is normal. Heavy ice, frost that returns within minutes, or ice that stays after a cycle points to a defrost or airflow problem. The diagnosis has to separate a control or defrost fault from a refrigeration fault, because the two can look alike from outside. The technician also records how long each defrost lasts and how often it starts.
Auxiliary heat runs all the time. The house is warm, but the system never seems to cycle off and the backup heat stays on. This is a symptom to diagnose, not a setting to accept. The diagnosis must separate a capacity limit in very cold weather from a refrigerant problem, or from thermostat settings that call for backup heat too early.
Cooling is fine but heating is weak, or the reverse. A heat pump that cools well but heats poorly, or heats adequately but cools weakly, has lost one of its two modes. The diagnosis must separate a reversing valve or control fault from a refrigeration or airflow fault. Both modes share the same coils and refrigerant, so a fault that shows in only one mode is worth checking in both. Each mode is measured against the other rather than against a guess.
A homeowner is weighing a heat pump at replacement time. If the current system is near the end of its service life, choosing between a heat pump and a conventional system is a real decision. This page covers heat pump specifics. The assessment must separate the system-choice question, whether a furnace, heat pump or hybrid suits this house, from any fault in the current system. The wider system choice is covered on heating installation, and the furnace side of the decision is covered on furnace services.
If the main problem is heating in a home with a furnace rather than a heat pump, heating repair is the better starting point.
3. How the Work Runs
A heat pump service visit runs in a fixed order: history first, then diagnosis in both heating and cooling, then refrigeration and airflow readings, written findings, the repair, and a final check in both modes. No part is condemned until both modes have been tested and the findings are written down.
1. Call and History
The process starts with the history. The technician asks which mode fails, when the problem started, and whether the auxiliary heat has been running more than expected. Call American HVAC Pros to describe these details, or to arrange the visit, before any equipment is opened. A clear timeline shapes every step that follows.
2. Both-Mode Diagnosis
The system runs in heating and in cooling. The technician watches the reversing valve operate, observes the defrost cycle start and end, and records how the system behaves in each mode. Nothing is assumed from the thermostat or from one mode alone. Running both modes rules out a fault that only shows in one season before a part is condemned, so a reversing valve is not blamed for a control problem.
3. Refrigeration and Airflow Readings
Charge and airflow are the shared foundation of both modes. A low charge or a restricted airflow path affects heating and cooling alike, and a fault in one mode often hides in the other. Readings are taken at the indoor and outdoor units, the air filter, the return and supply vents, and the condensate drain.
4. Findings in Writing
Before anything is authorised, the failed component or the capacity explanation is stated plainly and in writing. If the cause is a control or defrost fault, the findings say so. If the system is struggling in a hard freeze, that is stated as a capacity reality, with the auxiliary heat behaviour explained. You decide the next step with those findings in hand.
5. Repair or Correction
The work follows the findings: component repair, a control or defrost correction, or repair of the auxiliary heat. Where the findings point to heating-only work, the scope may overlap with heating repair. Where a furnace is paired with the system, furnace services covers that equipment.
6. Verification in Both Modes
A heat pump is only signed off when heating and cooling both prove out. The technician runs the system in each mode after the work, checks the defrost cycle, and confirms the auxiliary heat behaves as the findings predicted. If either mode is still unproven, the job is not complete. Confirmation in both modes means the valve has moved, the defrost has started and ended on its own, and the auxiliary heat has switched on only when the findings predicted.
4. What's Inside This Service
This section sets out four blocks: the reversing valve and defrost cycle, auxiliary heat, dual-season maintenance, and the heat pump versus furnace comparison. Each block says what the part is, when it matters, what happens, and what drives the cost.
(a) The Reversing Valve and Defrost Cycle
What it is. A conventional air conditioner has no reversing valve and no defrost cycle. A heat pump has both. The reversing valve changes the direction refrigerant flows, so the outdoor coil becomes the heat source in winter. The defrost cycle briefly reverses the system to clear frost from that coil.
When it matters. Both matter at the start of every season. A stuck valve leaves one mode weak. A defrost fault shows as ice that does not clear, or a defrost that repeats too often or never starts.
What happens. The technician runs both modes, confirms the valve moves, and watches the defrost start and end on its own. Control faults are separated from valve faults before anything is replaced.
What drives the cost. The failed part, whether the fault sits in the valve or its controls, and how easily the component can be reached.
(b) Auxiliary Heat
What it is. Auxiliary heat is the backup heat that supports a heat pump when outdoor air is too cold for the heat pump to carry the load alone. It is usually electric resistance strips or a furnace paired with the air handler. Its jobs are supporting defrost and covering cold snaps.
When it matters. Auxiliary heat matters on the coldest nights and during defrost. Constant running is a diagnosis trigger, not a setting to accept.
What happens. The diagnosis checks when the backup switches on and whether the thermostat settings call for it too early. Each cause has its own fix.
What drives the cost. Whether the backup element or its controls have failed, how the backup is sized for the house, and whether a furnace is involved, which routes that part of the work to furnace services.
(c) Dual-Season Maintenance
What it is. Dual-season maintenance is the care rhythm for a system that must work in both modes. A heat pump needs its coil, charge, airflow and controls checked in both modes, because a fault in one mode often stays hidden until the other season arrives.
When it matters. Care matters before each season, so the first hard freeze or heat wave is not the first real test. Filters, coils and drains matter in both seasons.
What happens. A visit checks the outdoor and indoor coils, the refrigerant charge, the airflow through the air filter and vents, and the condensate drain. The system is run in both modes before the visit closes.
What drives the cost. The number of coils and controls to check, the age of the system, access to the outdoor unit, and any repairs found, which wait for written findings.
(d) Heat Pump vs Furnace in North Texas
What it is. This is a comparison between two ways to heat the same house. A heat pump is one system that heats and cools by moving heat. A furnace makes heat, and an air conditioner handles cooling separately.
When it matters. It matters at replacement, when the current system is near the end of its service life, and in the conversion case, where a home with a furnace and air conditioner is considering a heat pump.
What happens. The assessment argues the choice from the home's load profile under the NOAA normals: a long cooling season, and a real but short heating season with hard freezes. It names the hybrid option, a heat pump paired with a furnace, as the middle route. No winner is declared for a house nobody has assessed.
What drives the cost. The equipment route chosen, auxiliary heat provision, and duct readiness.
5. Heat Pump Work and the Texas Framework
Heat pump work is air conditioning and refrigeration (ACR) work. In Texas, ACR contractors are licensed by the Texas Department of Licensing and Regulation (TDLR) under Texas Occupations Code Chapter 1302, with rules in 16 TAC Chapter 75. Offering ACR services in Texas requires that licence. The same framework applies to a heat pump, because its refrigerant circuit, reversing valve and controls are part of ACR work.
The framework also gives the homeowner a verification right. A company must employ an ACR contractor in each permanent location, and technicians must be TDLR-registered or certified and supervised. Before work starts, ask the company for its TDLR licence details and check them yourself at the [TDLR licence lookup](https://www.tdlr.texas.gov/LicenseSearch/). Licences are issued in classes. Class A covers units of any size. Class B covers cooling up to 25 tons and heating up to 1.5 million BTU per hour. Reading the lookup, match the licence class to the size of the system being quoted. A Class B licence stops at the 25-ton and 1.5 million BTU per hour limits, so a larger system needs a Class A holder.
For replacement work in the City of Dallas, a Mechanical (HVAC) permit is required when an HVAC system is installed, replaced or modified. It is pulled by a registered Air Conditioning Contractor through DallasNow, and each trade needs its own permit and inspections. For a homeowner, the permit is the record that the replacement was pulled by a registered contractor and inspected, so ask for the permit number before work starts and check that it covers the full scope of the replacement. Dallas-specific detail is on the Dallas page.
This page describes the framework only. It does not state a licence for American HVAC Pros. Ask the company for its licence details, verify them through the TDLR lookup, and do this before any work is authorised.
6. What Heat Pump Services Cost Depends On
The cost of heat pump work depends on the findings, not on a single figure. This page does not publish prices, ranges or averages. The factors below decide how large a job becomes.
The failed component. A reversing valve, a defrost sensor or a control board is a different job from a compressor failure. The component sets the scope of the work. Refrigeration circuit work, such as leak checks and recharging, is a separate scope because the circuit has to be proven sound first.
Whether auxiliary heat is implicated. Backup heat that runs constantly may point to a fault in the heat pump, in the backup heat, or in the controls. Each possibility changes the work. Auxiliary heat components and their controls are scoped only once they have been tested.
Diagnosis time in each mode. Heating and cooling both have to be run before a fault is confirmed, so the visit takes longer when the symptom shows in both modes.
System age and parts availability. An older system may need parts that are harder to source, which brings the repair-or-replace question forward.
The repair-or-replace horizon. Whether a repair leaves the system with a useful service life ahead, or whether the system is near the end of that life, shapes the decision. Where the answer is replacement, heating installation covers that route. The findings should state that horizon plainly.
Every factor above is confirmed through findings in writing before any work is authorised. The only commitment this page makes about cost is that you see the cause, the options and the scope in writing first. For heating-only symptoms, heating repair explains how that work is scoped.
7. Questions People Ask
How can one system both heat and cool?
A heat pump uses a reversing valve to change the direction refrigerant flows through its two coils. In summer, the indoor coil absorbs heat from the house and the outdoor coil releases it outside. In winter the roles swap: the outdoor coil absorbs heat from outside air, and the indoor coil releases it into the home. One outdoor unit, one refrigerant circuit and one set of indoor coils do both jobs. That single circuit is why a heat pump is checked in both modes.
Why does my heat pump blow cool air sometimes in winter?
In heating mode, the outdoor coil can frost when it runs cold. The system then runs a defrost cycle, briefly reversing to clear the frost. During that short cycle, air from the vents can feel cool for a few minutes, and this is normal. It is not normal when defrost runs too often, runs for a long time, leaves ice on the outdoor unit, or never seems to end. Those patterns point to a defrost or control fault, and the diagnosis separates that fault from a refrigeration or airflow problem.
What is auxiliary heat, and should it run all the time?
Auxiliary heat is backup heat, usually electric resistance strips or a furnace paired with the air handler. It supports defrost and covers cold snaps when outdoor air is too cold for the heat pump to carry the load alone. It should not run all the time as a matter of course. Constant running is a symptom to diagnose. The check looks at thermostat settings, the defrost cycle, and whether the heat pump is reaching its capacity limit in cold air.
Is a heat pump a realistic choice in Dallas?
NOAA's 1991 to 2020 normals for Dallas Love Field show a long, severe summer and a January mean daily minimum of 37.9°F, with hard freezes in the coldest snaps. In that pattern a heat pump carries most of the load, and auxiliary heat or a furnace covers the snaps. A heat pump is a realistic option for some homes, and a furnace with an air conditioner, or a hybrid, is another. No option suits a house nobody has assessed, so a site visit and written findings settle the comparison. Local detail is on the Dallas page.