Arkansas spans several climate zones and regularly sees temperatures that drop below freezing in fall, winter, and early spring. A freeze can crack PVC pipes, ruin solenoids, corrode wiring, and erase controller programs. Servicing your sprinkler controller and related electrical components before freeze season is a high-return, relatively low-cost task that protects irrigation assets and prevents costly spring repairs.
The goal is to complete controller servicing well before the first expected hard freeze in your area. That generally means late September through November for most of Arkansas, but timing varies by county and elevation. Treat the controller service as part of a broader irrigation winterization plan and schedule it at least 1-2 weeks before consistently freezing overnight temperatures appear.
Before putting hands on the controller or wiring:
1.1. Verify the controller is off or power is disconnected before opening the cabinet.
1.2. Remove and replace the controller backup battery (commonly a 9V or AA pack). Even if the battery appears OK, replace it annually before winter; low batteries can cause clock or program loss during a freeze.
2.1. Look for water, condensation, insect nests, or rodent intrusion. Wipe dry and remove debris.
2.2. Check the door seal and gaskets; apply silicone caulk where gaps allow moisture entry. Replace cracked enclosures.
3.1. With power connected and using proper precautions, measure the transformer output with a multimeter. Typical controllers use about 24 VAC between the transformer hot and common. Confirm it is within the expected range (usually 20-26 VAC depending on model).
3.2. Inspect the transformer mounting, outlet plug, and any inline fuse. Replace blown fuses with the correct type and rating.
4.1. Tighten terminal screws and look for loose or corroded connections. Loose terminals are a frequent cause of intermittent faults.
4.2. Inspect the common wire for corrosion where it connects in the controller and in the valve boxes. Replace or re-terminate corroded connections.
5.1. Use the controller manual-run or test mode to energize each station for 10-30 seconds. Walk the system to confirm each valve opens and the correct zone waters.
5.2. If a zone fails to start, use a plug-in jumper wire between the common and the station terminal at the controller to rule out wiring or valve problems.
5.3. If the valve still does not open when directly energized at the controller, suspect a failed solenoid or valve mechanical issue.
6.1. Open valve boxes and use a flashlight to look for water, rodents, or broken fittings. Dry the box and repair any leaks.
6.2. Inspect splice connectors and waterproofing. Replace tape-only splices with gel-filled connectors or heat-shrink waterproof butt splices.
6.3. Look for chewed or damaged control wires, especially near valve boxes and entry points into the house or controller cabinet.
7.1. Remove and test problematic solenoids with a multimeter for coil continuity (typical coil resistance varies by valve, often 20-50 ohms for latching or 15-60 ohms for standard solenoids). Consult the valve manual for expected resistance ranges.
7.2. Replace solenoids that are open, shorted, or show intermittent resistance changes when flexed.
7.3. If valves are sticky or slow, disassemble and clean or replace diaphragms and springs before freeze season.
8.1. Test the rain sensor by lifting its cover (many interrupt the common or station circuit). Clean the sensing surface and verify it toggles the controller to “sensor” or “off.” Replace old sensors that do not trip reliably.
8.2. For freeze sensors, confirm the setpoint; set the freeze cutoff to a temperature that protects plantings in your area (commonly 33-36 degrees F). Test the activation by simulating a cold event following the manufacturer’s instructions.
9.1. Back up the controller program if the model supports external storage or take photos of settings to restore later.
9.2. Adjust seasonal percentages, run times, and start times for cooler weather. Consider shortening or suspending root-watering cycles as plants go dormant, but follow landscape and turf needs.
9.3. Disable automatic winter cycles that could mistakenly run during a warm period and then be followed by a freeze.
10.1. Inspect or install a dedicated irrigation surge suppressor to protect the controller from lightning and power surges.
10.2. Verify the controller enclosure and transformer are properly grounded to reduce damage from transient voltage.
11.1. Some property owners choose to leave the controller powered but in “off” or “rain” mode to protect electronics while preventing accidental watering during freezes.
11.2. Others fully disconnect the transformer and leave the controller powered only by battery if needed for clock retention. If you disconnect power, note that some controllers allow internal capacitor-based memory for a short time; confirm your model’s behavior.
12.1. Record battery replacement date, transformer voltages, any replaced solenoids, and suspected wiring issues.
12.2. Schedule a post-freeze inspection in spring to verify no damage occurred.
Many controllers use a small replaceable battery (9V or AA) for real-time clock backup or a non-replaceable supercapacitor. Replace replaceable batteries annually before freeze season. If your controller uses a supercapacitor, check that the clock retains time after power removal; if not, plan for a service replacement or a controller swap.
Pay special attention to the common conductor: it carries current from every valve and is a single point of failure. At each valve box and at the controller, look for green or whitish corrosion deposits on copper wires and terminal screws. Clean with a small brush and re-terminate with proper connectors. When splicing outdoors, never rely on plain electrical tape alone.
Sensors degrade over time. For freeze sensors, set the threshold conservatively (slightly above freezing) if you want to prevent irrigation before frost. Test sensors by manually tripping them and confirming the controller responds immediately. Replace sensors that are slow to react or that allow moisture ingress.
Maintain a simple log that includes:
Review the log each spring so you can prioritize repairs and confirm that components that were problematic last fall were addressed.
Servicing your sprinkler controller before Arkansas freeze season reduces the risk of freeze-related damage and protects your irrigation investment. Key takeaways:
Create a simple checklist from this article and perform the tasks in sequence to minimize missed items. A one-hour, methodical service visit can save hundreds or thousands of dollars in repairs and prevent landscape loss when Arkansas freezes arrive.