Lone Star Cooling and Heating
Get help with Thermostats & Controls
Call Lone Star Cooling and Heating, have us call you, or describe the issue.
Prefer to talk?
Call (325) 219-0005Thermostats that go blank, read the wrong temperature or stop controlling the system, sorted from faults in the equipment itself, and replaced with a control that suits the heating and cooling it runs.
01Thermostats
Some of these start at the thermostat and some only show up there. Which is which gets checked at both ends.
A dark screen usually means the thermostat has lost power: flat batteries in a battery model, a tripped breaker or blown low-voltage fuse at the equipment, or a safety switch at the equipment that has cut the control circuit. Power is checked at the equipment before the thermostat is blamed.
The thermostat shows it is calling for heat or cooling, but nothing starts. The fault can sit in the thermostat, the thin wires running to the equipment, or the equipment itself, and a technician tests the signal at each end to find which.
Sun on the wall, a supply vent or lamp nearby, or a draft coming through the wall behind the thermostat can all skew what it measures, and older sensors can drift. The system then heats or cools to a number the room does not actually feel.
On a heat pump, the thermostat tells a reversing valve which way to run. A replacement thermostat set up for the wrong equipment type, or with the valve setting reversed, makes the system heat when asked to cool and cool when asked to heat.
A thermostat mounted in the path of a supply vent, or set up with the wrong cycle settings for the equipment, can switch the system on and off far more often than it should. Correcting the location or the setup usually settles it, provided the equipment itself is healthy.
02Urgency
A faulty control is usually an annoyance. Weather and heating that will not stop change that.
Thermostats & Controls
Serving Abilene, TX.
03Control or equipment
A new thermostat fixes thermostat faults and nothing else, so telling the two apart comes first.
The display is blank or frozen, settings change on their own, or the reading is clearly wrong while the equipment runs normally whenever it is called. Problems that began right after a battery change, a power cut or a new thermostat being fitted also point at the control.
The thermostat calls for heat or cooling, and the equipment starts but does not deliver, trips a breaker, makes new noises or shows a fault light on its control board. Replacing the thermostat first in these cases only delays the repair the equipment actually needs.
04Matching the equipment
Different equipment asks different things of the control on the wall.
Most thermostats work by sending a low-voltage signal down separate wires, one each for heating, cooling and the fan. A simple furnace and air conditioner need only a few of those. A heat pump needs another to switch its reversing valve and one more to bring on backup heat, and equipment with two stages of heating or cooling needs a thermostat that can call for each stage separately.
Some variable-speed and high-end systems go further, replacing the separate wires with a data link to a matched control. A thermostat chosen for its screen alone can run equipment it does not understand badly: backup heat coming on when the heat pump could manage, full capacity called every time, or a stage never used. The equipment type and the wires actually present decide which thermostats fit.
05Placement
A thermostat reads the air around it and assumes the rest of the building feels the same.
Sunlight through a window warms the thermostat and the wall it hangs on, so it reads high during the day and the cooling runs longer than the room needs.
Air blowing straight from a vent onto the thermostat satisfies it before the rest of the room has changed temperature, which shortens cycles and leaves other rooms behind.
Air from an attic, crawl space or outside wall can leak through the hole behind the thermostat where its wires enter, and that air is often much warmer or colder than the room.
Lamps, televisions, ovens and sunny hallways near the thermostat add warmth it takes for the whole building, so the heating stops early and the cooling runs on.
06Questions
If the thermostat is blank, frozen or showing a clearly wrong temperature while the equipment runs normally when it is called, the thermostat is the likely fault. If the thermostat is calling and the equipment starts but does not heat or cool, trips a breaker or shows a fault light, the problem is in the equipment.
No. A heat pump needs a thermostat that can switch its reversing valve and bring on backup heat when needed, and it has to be set up for that equipment type. A thermostat made only for a furnace and air conditioner can leave the system stuck in one mode or lean on backup heat too often.
Yes. It controls the system by the temperature where it hangs, so sun, a nearby vent, a kitchen or a drafty outside wall all mislead it. An inside wall in a room people actually use, away from those sources, gives it a fair reading.
Most often it has lost power. Battery models may simply need new batteries. Wired models draw power from the equipment, so a tripped breaker, a blown fuse on the control board or a safety switch that has opened at the furnace or air handler can all leave the screen dark.
A smell of gas, a carbon monoxide alarm, a burning electrical smell, or no heat or cooling in dangerous weather: urgent. A system that runs longer than it used to, a new noise or one room that is off: worth a visit soon, but not tonight.
What the system is doing, when it started, what the thermostat is set to and what it reads, and whether the outdoor unit is running. The age of the equipment and a photo of its label help a technician arrive prepared.
Lone Star Cooling and Heating
Call Lone Star Cooling and Heating, have us call you, or describe the issue.
Prefer to talk?
Call (325) 219-0005