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Plug-In Cooling Thermostat for Attic & Ventilation Fans
Overview
Digital Cooling Thermostat Outlet for Attic Fans, Exhaust Fans & Ventilation Control
The YeloDeer EF03-CS Digital Cooling Thermostat Outlet is a plug-in temperature controller designed specifically for ventilation fans and fan-based cooling equipment. It automatically turns the connected fan on when the detected temperature rises above your selected temperature and turns it off after the temperature drops below the configured lower limit.
It is suitable for attic fans, exhaust fans, inline duct fans and other compatible plug-in ventilation fans used to remove accumulated heat and improve airflow.
This is a cooling controller, not a heating thermostat. Its control logic is designed to activate a ventilation fan when the surrounding temperature becomes too high.
Quick Fit Snapshot
Key Benefits
Recommended Applications
Important Before You Order
This controller is designed for ventilation fans only.
Do not use it to directly control compressors, refrigerators, freezers, air conditioners or other compressor-based cooling equipment.
The maximum fan load is 3A / 360W at 120V. Always check the voltage, wattage and current rating of the connected fan before use.
Cooling Thermostat vs. Heating Thermostat
The cooling and heating versions may look similar, but their operating logic is opposite. Select the controller according to whether you need to remove heat or provide heat.
For heating control, choose the YeloDeer Digital Plug-In Heating Thermostat with Timer.
Applications
Designed for Fan-Based Cooling
The YeloDeer EF03-CS is designed to control compatible plug-in ventilation fans according to the temperature detected by its external probe. It is most suitable for locations where warm air accumulates and automatic ventilation is needed.
Attic & Home Ventilation
Heat can accumulate quickly in attics and other enclosed spaces. The controller can automatically start a compatible ventilation fan when the measured temperature rises above the selected temperature.
Greenhouse & Grow Room Ventilation
The controller can operate a compatible ventilation fan according to the temperature in the plant or growing area. Position the probe where it can measure representative air temperature without being heated directly by sunlight or grow lights.
Garage, Workshop & Equipment Areas
The thermostat can also control compatible plug-in fans used to remove accumulated heat from garages, workshops, utility spaces and fan-ventilated equipment areas.
Compatibility Checklist
Do Not Use This Controller For
- Heating cables or pipe heat tape
- Heat mats, heating pads or space heaters
- Air conditioners
- Refrigerators or freezers
- Compressors
- Compressor-based dehumidifiers
- Fans that exceed 3A / 360W
- Hardwired equipment without a compatible plug
- Wet or unprotected outdoor installations
- Life-support, fire-protection or other critical safety systems
Important: A device may be rated below 10A but still be unsuitable if it contains a compressor.
This controller is specifically intended for ventilation fans. Do not select compatibility based only on wattage or current.
For heating applications, choose the YeloDeer Digital Plug-In Heating Thermostat with Timer.
Specifications
Product Specifications
| Model | EF03-CS |
| Product Type | Digital plug-in cooling thermostat controller |
| Primary Application | Ventilation fan and fan-based cooling control |
| Power Supply | 120V AC, 60Hz |
| Maximum Fan Load | 3A / 360W at 120V |
| Maximum Resistive Load | 10A / 1200W at 120V |
| Temperature Setting Range | 14°F to 104°F (-10°C to 40°C) |
| Temperature Display Range | -22°F to 158°F (-30°C to 70°C) |
| Temperature Unit | °F / °C switchable |
| Sensor Calibration Range | ±9°F (±5°C) |
| Lower Limit Adjustment | 1–20°F (1–10°C) |
| Default Lower Limit | 10°F (5°C) |
| Timing Function | 0–10 hours |
| Sensor Probe Length | 6.6 ft (2 m) |
| Outlet Cord Length | 7.8 ft (2 m) |
| Forced Cooling Mode | Supported |
| Factory Reset | Supported |
| Installation Type | Plug-in installation; no hardwiring required |
| Not Designed For | Compressors, air conditioners, refrigerators, freezers or heating equipment |
How Temperature Control Works
The external probe continuously measures the surrounding temperature.
When the measured temperature rises above the selected temperature, the cooling indicator turns on and the connected fan starts.
When the measured temperature drops below the selected temperature minus the configured lower limit, the fan stops.
Temperature Control Example
A smaller lower-limit value provides tighter temperature control but may cause more frequent fan cycling. A larger value reduces cycling but allows a wider temperature range.
Timing Function
The timing function allows thermostat-controlled operation to remain active for a selected period from 0 to 10 hours.
During the selected period, the fan still turns on and off automatically according to the set temperature and lower-limit setting. The timer does not force the fan to run continuously.
While timing is enabled, the display alternates approximately every three seconds between the current temperature and the remaining time.
Forced Cooling Mode
Forced cooling mode overrides normal temperature control and keeps the connected fan running continuously. The display shows “MA” while this mode is active.
Sensor Calibration
The displayed temperature can be calibrated by up to ±9°F (±5°C) when the reading differs from a trusted reference thermometer.
Example: If the controller displays 82°F but a reliable thermometer shows 85°F, set the calibration value to +3°F.
If the controller displays 82°F but the actual temperature is 79°F, set the calibration value to -3°F.
Probe Placement
Load Selection Reminder
For ventilation fans, do not exceed 3A / 360W at 120V.
The 10A / 1200W rating applies only to resistive loads and does not make compressor-based cooling equipment compatible.
Always check the equipment nameplate before connecting a device.
Installation
Basic Installation
- Confirm that the ventilation fan operates on 120V AC and does not exceed 3A / 360W.
- Secure the sensor probe in a location that represents the temperature of the target area.
- Keep the probe away from direct sunlight, strong localized heat and direct cooling airflow.
- Plug the thermostat controller into a grounded 120V AC outlet.
- Plug the compatible ventilation fan into the controller outlet.
- Install the controller in a dry, well-ventilated location.
- Turn on the controller and select the desired temperature.
- Confirm that the fan starts and stops correctly before leaving the system unattended.
Attic Fan Installation
- Choose a probe location in the attic where heat commonly accumulates.
- Avoid direct contact with the roof deck, metal surfaces or insulation-covered heat sources.
- Do not place the probe directly in front of the fan or exhaust airflow.
- Secure the probe using the included suction cup or another suitable fastener.
- Connect the attic fan to the controller.
- Set the fan activation temperature.
- Allow the attic temperature to change and verify correct operation.
Greenhouse or Grow Room Installation
- Place the probe near the area where representative air temperature should be measured.
- Keep it away from direct sunlight and direct heat from grow lights.
- Do not place it directly in the intake or exhaust airflow.
- Connect a compatible plug-in ventilation fan.
- Set the desired activation temperature.
- Adjust the lower limit if the fan cycles too frequently.
Turn the Controller On or Off
Set the Activation Temperature
- Press the up or down button to adjust the desired activation temperature.
- Select a value between 14°F and 104°F (-10°C and 40°C).
- Press the power/confirm button to save the setting.
Use Forced Cooling Mode
- Press and hold the designated forced-cooling button for approximately three seconds.
- The screen will display “MA,” and the cooling indicator will remain on.
- The connected fan will run continuously.
- Press and hold the same button for approximately three seconds to exit forced cooling mode.
Advanced Settings
Press and hold the up, down and confirm buttons together for approximately three seconds to enter the advanced settings menu.
Important Installation Notes
Safe Probe Placement
Environmental Safety
Install the controller in a dry, well-ventilated location.
Avoid moisture, rain, direct sunlight, standing water and environments where the electrical connection may become wet.
Keep the controller away from children and pets, and comply with all applicable local electrical regulations.
FAQ
Product Basics
Is this thermostat designed for heating or cooling?
This model is designed for cooling and ventilation control. It turns a connected fan on when the measured temperature rises above the selected setting.
For heating cable, heat tape, heat mats or other heating equipment, choose the YeloDeer Digital Plug-In Heating Thermostat with Timer.
Can I use this controller with an attic fan?
Yes. It is designed for compatible plug-in attic and ventilation fans that operate on 120V and do not exceed 3A / 360W.
Can I use it with an inline duct or exhaust fan?
Yes. It can control a compatible plug-in inline duct fan, exhaust fan or similar ventilation fan within the rated fan load.
What is the maximum load for a fan?
The maximum fan load is 3A / 360W at 120V.
Check both the current and wattage shown on the fan nameplate before connecting it.
Compatibility
Why does the specification also show a 10A / 1200W resistive load?
The 10A / 1200W rating applies to resistive electrical loads. Ventilation fans are motor loads and must remain within the separate 3A / 360W fan-load rating.
Do not use the higher resistive-load rating to determine fan compatibility.
Can I use this controller with an air conditioner?
No. The controller is not designed to directly control air conditioners or compressor-based equipment.
Can I use it with a refrigerator or freezer?
No. Do not connect refrigerators, freezers or other compressor-based refrigeration equipment.
Can I use it with a dehumidifier?
Do not use it with a compressor-based dehumidifier. This controller is intended for ventilation fans.
Can I use it with a heating cable or heater?
No. This model uses cooling-control logic and is not intended for heating applications.
Choose a heating thermostat for heat tape, heating cable, heat mats, drum heaters or other heating devices.
Settings & Operation
At what temperature will the fan turn on and off?
The fan turns on when the measured temperature rises above the selected temperature.
It turns off after the temperature falls below the selected temperature minus the configured lower-limit value.
For example, with an 85°F setting and a 10°F lower limit, the fan starts above 85°F and stops after the temperature falls below 75°F.
What is the adjustable lower limit?
The lower limit determines how far the temperature must drop below the selected setting before the fan turns off.
It can be adjusted from 1–20°F (1–10°C), with a default setting of 10°F (5°C).
Why does my fan turn on and off too frequently?
The lower-limit value may be too small, or the probe may be too close to the fan, direct sunlight or rapidly changing airflow.
Move the probe to a more representative location or increase the lower-limit value to reduce frequent cycling.
What does the 0–10 hour timer do?
The timer limits thermostat-controlled operation to the selected period.
During that period, the fan still starts and stops according to the measured temperature. The timer does not make the fan run continuously.
What is forced cooling mode?
Forced cooling mode keeps the connected fan running continuously, regardless of the measured temperature.
The display shows “MA” while this mode is active.
Can the displayed temperature be calibrated?
Yes. The sensor reading can be adjusted by up to ±9°F (±5°C) to match a trusted reference thermometer.
Can I switch between Fahrenheit and Celsius?
Yes. The temperature unit can be switched between °F and °C in the advanced settings menu.
Probe Placement
Where should I place the sensor probe?
Place the probe in a location that represents the temperature of the area you want to ventilate.
For an attic, position it in the air space where heat accumulates rather than directly against the roof or another hot surface.
Where should the probe not be installed?
Avoid direct sunlight, direct contact with heating surfaces, direct cooling airflow, fan exhaust paths and locations with rapidly changing airflow.
Alarm Codes & Troubleshooting
What does the E1 error code mean?
E1 indicates an external temperature-probe fault, such as an open circuit or short circuit.
The thermostat stops cooling control when this error occurs.
Use forced cooling mode only as a temporary measure, then inspect the probe and contact YeloDeer support if the problem continues.
What does the H1 alarm mean?
H1 indicates that the thermostat power board has overheated to approximately 176°F (80°C).
The controller temporarily stops operation. After the internal temperature falls below approximately 149°F (65°C), normal control resumes.
Disconnect the load and confirm that it does not exceed the rated capacity. Allow the controller to cool naturally and contact support if the alarm returns.
Why is there no display?
Check the power supply, confirm that the outlet is working and make sure the controller is turned on.
If the housing, cord or plug is visibly damaged, stop using the controller.
Why is the connected fan not operating?
Check the fan connection, fan power switch, temperature setting and lower-limit setting.
Confirm that the measured temperature is high enough to activate cooling and that the fan itself operates correctly when connected directly to a suitable outlet.
Why does the temperature reading appear incorrect?
The probe may be damp, contaminated, positioned near a localized heat source or exposed to direct cooling airflow.
Clean and dry the probe, move it to a representative location and use the calibration function if needed.
How do I restore the factory settings?
Enter Setting 5 in the advanced settings menu and select the factory-reset option.
A factory reset erases customized settings. Use it only when you want to restore the original defaults.
Safety & Support
Can I install the controller outdoors?
The controller must remain dry and protected from rain, snow, condensation and standing water.
For greenhouses, garages, sheds or semi-outdoor locations, install it in a dry, protected and well-ventilated area.
What should I do if I am unsure whether my fan is compatible?
Email yelodeer@yelodeer.com and include:
- The fan type
- Voltage
- Current rating in amps
- Wattage
- A photo of the equipment nameplate
- Whether the fan is plug-in or hardwired
- A brief description of the installation area
Our support team can help review whether the controller is suitable for your application.
What warranty does this controller include?
The YeloDeer plug-in thermostat includes a one-year limited warranty from the date of purchase.
Warranty service is subject to the warranty terms available on the YeloDeer website.
Related Resources
- For heating control, choose the YeloDeer Digital Plug-In Heating Thermostat with Timer.
- For compatibility or installation assistance, contact yelodeer@yelodeer.com with your equipment details.
Common Questions
This FAQ section is based on common customer questions about YeloDeer digital plug-in thermostat outlets for heating and cooling control.
If you are not sure which thermostat to choose, please contact us at yelodeer@yelodeer.com with your device type, voltage, wattage, application photos, and whether you need heating control or cooling fan control.
Choose the heating thermostat if you want to control a heater, pipe heat tape, heat mat, warming pad, incubator heater, greenhouse heater, or other heating device.
Choose the cooling thermostat if you want to control an attic fan, gable fan, exhaust fan, inline duct fan, greenhouse fan, grow room fan, garage fan, or ventilation fan.
The products may look similar, but their control logic is different.
No, we do not recommend switching them.
The heating thermostat is designed to turn on when the temperature is too low.
The cooling thermostat is designed to turn on when the temperature is too high.
Using the wrong version may cause the connected device to operate opposite of what you expect.
The probe measures the temperature used by the controller.
Place the probe where you want the thermostat to sense temperature.
For heating applications, place it near the area that needs warmth or freeze protection.
For fan applications, place it in the hot air area where ventilation should begin.
The controller and plug connection should be kept dry and protected.
They may be used for outdoor-related applications only if the outlet, controller, plug, and connection area are protected from rain, snow, condensation, and standing water.
Do not leave the controller exposed directly to weather.
The timer allows the connected device to run for a selected period.
It can be useful for temporary heating, temporary ventilation, greenhouse cycles, workshop use, equipment cooling, or other timed operation needs.
Before use, check:
• Device voltage
• Wattage
• Current draw
• Plug type
• Whether the device can safely cycle on and off
• Whether the device is heating or cooling equipment
• Whether the device is within the thermostat’s rated load
Do not exceed the rated load.
Frequent cycling is usually caused by probe placement or a narrow temperature differential.
Try adjusting:
• Probe location
• Temperature differential
• Target temperature
• Airflow around the probe
• Distance between the probe and the heating or cooling device
A more stable probe location usually improves control.