Capacitor drifting below rated value
The most common finding by a wide margin. Every start against a weak capacitor draws excess current and heats the windings, so the part quietly damages the compressor while it fails.
Annual cooling service
AC tune-up in Sonterra, TX that produces numbers you can compare next year
A service visit that records nothing cannot warn you about anything. Every reading is written down against your equipment so this spring can be measured against last spring.
The seasonal tune-up has a bad reputation and it has earned some of it. A visit consisting of a filter change, a rinse of the outdoor coil and a sticker on the cabinet is a cleaning service. It may be worth having, but it cannot tell you that a capacitor has dropped seven microfarads since last year, because nobody measured it either year.
Early warning is the only real product of a maintenance visit. Components in a cooling system fail on a trajectory, not a cliff, and every point on that trajectory is measurable. Catching the decline in April costs a small part. Missing it means a callout in July with a hot house and an out of hours rate attached.
What gets recorded
Run capacitor value, compressor and fan amperages against nameplate, total external static pressure, temperature split across the coil, superheat and subcooling, condensate flow and float switch function, and contactor condition. All of it written down against your equipment.
- Capacitor microfarads compared against the nameplate rating
- Compressor and condenser fan amp draw under running load
- Static pressure read on both sides of the air handler
- Superheat and subcooling calculated for the day's conditions
- Condensate trap, drain fall and float switch proven to work
Why measured maintenance is different
The difference between an inspection and a measurement, and why only one of them predicts anything.
An inspection tells you the condition of something today. A measurement compared against last year's measurement tells you the direction it is travelling in, which is a far more useful thing to know. A run capacitor rated at forty five microfarads reading forty three is healthy. The same capacitor reading forty three after reading forty four and a half twelve months ago is on a trend, and the sensible moment to change it is now rather than during a heat event.
The same logic applies across the system. A compressor drawing slightly more current each year is telling you something about internal friction or about the load being placed on it. Static pressure climbing season over season means the duct system is getting more restricted, usually because a filter grille has been replaced with something more restrictive or because a coil is loading up. Neither of those is visible.
Temperature split across the indoor coil is the single most informative quick reading, and it is also the most frequently misread. The expected split varies with indoor humidity, and a technician quoting a fixed twenty degrees regardless of conditions is applying a rule of thumb rather than reading the system. Superheat and subcooling together give a much more precise picture of whether the charge and the metering device are behaving.
The condensate side gets as much attention as the refrigerant side, because it causes more property damage. A trap that has dried out, a drain run that has settled and lost its fall, a pan rusting through, or a float switch that has never been tested are all common and all cheap to deal with in spring. The same items in July arrive as water coming through a ceiling.
What the visit includes
A measured service on the cooling system, with the outdoor and indoor sides both covered.
- Condenser coil cleaned and its condition recorded, not just rinsed
- Electrical components measured rather than inspected
- Refrigerant condition assessed by calculation, not by topping up
- Condensate path proven end to end, including the safety switch
What a spring visit typically finds
Six things that turn up regularly, all of which are cheap in April and expensive in July.
None of these announce themselves. A system carrying every one of them will still cool a house on a mild day in spring, which is exactly why they survive until the first serious heat.
The list below is roughly in order of how often it appears on a first visit to a system that has not been serviced with instruments before.
Condenser coil loaded with debris
Cottonwood, grass clippings and dust packed into the fins. Heat rejection falls, head pressure climbs, and the compressor runs hot for the whole season.
Contactor contacts pitted
Arcing every cycle burns the faces. Voltage drop across them rises, the compressor sees less than rated voltage on start, and eventually they weld closed.
Condensate trap dry or drain blocked
A dry trap lets the blower pull air through the drain. A blocked one backs water into the pan, and the float switch is the only thing between that and your ceiling.
Static pressure above the blower table
A restricted duct system reduces airflow across the coil, which lowers suction pressure, invites freezing and cuts capacity before anything has actually failed.
Charge slightly low from a slow leak
Found by calculation rather than by topping up. A system losing refrigerant has a leak, and finding it once is cheaper than adding gas every spring.
What happens during the visit
Six stages, roughly an hour and a half on a single system in reasonable condition.
The visit is booked long enough to do it properly. A tune-up compressed into thirty minutes can clean a coil and change a filter, and it cannot take a meaningful set of readings on both sides of the system.
Baseline readings before anything is touched
The system is run and measured in the state you have been living with, because cleaning first and measuring afterwards hides what the year has done.
Electrical measurement
Capacitor value, contactor condition and voltage drop, compressor and fan amperages compared against nameplate figures.
Condenser cleaning
Coil cleaned from the inside out with appropriate cleaner, fins combed where damaged, and clearance around the unit checked.
Indoor side
Blower wheel condition, evaporator coil, filter type and pressure drop, and total external static pressure read across the air handler.
Refrigerant assessment
Superheat and subcooling calculated for the conditions on the day and compared against the manufacturer target for the metering device fitted.
Condensate and handover
Trap primed, drain flow proven, float switch tested, then the readings written up and compared against last year where a record exists.
What a maintenance plan should actually buy you
An honest look at the maintenance agreement, including when it is not worth having.
Maintenance agreements in this trade vary from genuinely valuable to close to worthless, and the distinguishing feature is simple: does the visit produce recorded readings against your specific equipment. If it does, you are buying early warning and a documented history that supports repair and replacement decisions. If it does not, you are pre-paying for a cleaning service and a priority phone number.
There is a second thing worth checking, which is what the agreement does to your position in the queue during a heat event. Priority scheduling has real value in July, and it is one of the few benefits that is genuinely hard to obtain any other way. An agreement that promises priority and then books solid every morning cannot deliver it.
It is also fair to say when an agreement is not worth it. A household with a system in its final year or two, already planning replacement, is usually better off paying for a single measured visit and putting the difference toward the new equipment. Nobody here will push an agreement onto a system that is about to be removed.
Questions to ask about any maintenance plan
- Will the visit record numerical readings against my equipment
- Will I be given those readings, and compared against the previous year
- Does it include the condensate path and the safety switch, or only the refrigerant side
- What does priority scheduling actually mean during a heat event
- Is the agreement worth having on a system this close to replacement
Tune-up questions
Timing, frequency, what is included and whether it is worth it on older equipment.
Spring, before the first genuinely hot week. That timing gives you a longer appointment, a technician who is not being pulled toward an emergency, and time to order any part that turns out to be needed.
The worst time is during a heat event, when every service company is running emergency calls and a routine booking sits behind all of them.
For a residential cooling system in normal use, yes. The components that drift do so on an annual timescale, and a yearly reading is enough to establish a trend.
Systems in unusually dirty environments, near heavy cottonwood, or running long hours for a home business benefit from a second condenser clean partway through the season, which is a shorter and cheaper visit.
No, and a company offering routine topping up is describing a leak they are not fixing. A sealed system does not consume refrigerant, so if the charge is low there is a hole somewhere.
The service assesses the charge by calculation. If it is low, that is reported as a leak to be located rather than quietly corrected each spring at your expense.
Usually yes, though what you are buying shifts. On aging hardware the point is not squeezing out another percent of efficiency, it is being warned. A part caught drifting in April becomes a scheduled half hour instead of a July callout with a hot house attached.
The record matters too. Several seasons of numbers moving in one direction tells you far more about when to replace than any single visit or any opinion offered on the afternoon the unit finally quits.
You get told what it is, what the reading was, and a flat rate price for the repair, and nothing happens until you approve it. Where a part is inexpensive and carried on the van it can usually be done during the same visit.
You also get told when something is worth watching rather than fixing. A capacitor that has drifted slightly but is still inside tolerance goes on the record with a note, not onto an invoice.
The visit covers the cooling system and the shared components: blower, filter, ductwork, static pressure and condensate. The heating side has its own checks that are genuinely seasonal, particularly combustion analysis, which needs to be done in heating conditions.
Combining them into one visit sounds efficient and produces a worse result on both. Autumn for heating and spring for cooling is the honest answer.
Get the readings taken before the weather tests the system
Spring appointments in Sonterra, TX are longer, cheaper and far more useful than a July callout.
Call with the age and type of the system and whether it has been serviced with instruments before. A first measured visit on a system with no history takes a little longer, because there is no baseline to compare against and one is being created.
If you have paperwork from previous visits, keep it out. Any recorded readings from earlier years make the trend visible immediately rather than after another twelve months.
What you are left with
- A written sheet of every reading taken on the day
- A comparison against last year wherever a record exists
- A note of anything drifting but not yet worth replacing
- A flat rate price for anything that does need attention
- A clean condenser and a proven condensate path