1. Introduction
This manual provides essential information for the proper installation, operation, and maintenance of the Johnson Controls A91PAA-2C Thermistor Temperature Duct Sensor. Designed for precise temperature measurement within duct systems, this sensor is intended for use with compatible Johnson Controls Series R81Q and R93 controllers to manage Series M100 actuators and R353 series sequencing modules. Adherence to these instructions will ensure optimal performance and longevity of the device.
2. Product Overview
The Johnson Controls A91PAA-2C is a highly sensitive thermistor-based temperature sensor specifically engineered for duct applications. It accurately measures air temperature within a range of 4°C to 32°C (39.2°F to 89.6°F), providing critical data to connected control systems. Its robust design ensures reliable performance in industrial and HVAC environments.
Figure 1: Johnson Controls A91PAA-2C Thermistor Temperature Duct Sensor. This image displays the compact, rectangular enclosure of the sensor, featuring a visible temperature adjustment dial on its side and a probe extending from the top. The device is designed for integration into ductwork for temperature monitoring.
3. Safety Information
WARNING: Improper installation or use of this product can result in personal injury, property damage, or equipment malfunction. Always observe the following safety precautions:
- Disconnect all power to the system before installing or servicing the sensor.
- Installation and wiring must be performed by qualified personnel in accordance with all local and national electrical codes.
- Do not exceed the specified electrical ratings of the device.
- Ensure proper grounding to prevent electrical shock.
- Avoid exposing the sensor to corrosive chemicals or extreme physical stress.
- This device is not intended for life-safety applications.
4. Setup and Installation
The A91PAA-2C sensor is designed for duct mounting. Follow these general guidelines for installation:
- Power Disconnection: Ensure all power to the HVAC system and associated controls is completely disconnected before beginning installation.
- Mounting Location: Select a location in the ductwork that provides an accurate representation of the air temperature, away from direct heat sources, cooling coils, or air stratification.
- Mounting: Securely mount the sensor enclosure to the duct using appropriate fasteners. Ensure the probe extends into the airflow as intended.
- Wiring: Connect the sensor to the compatible Johnson Controls controller (e.g., R81Q, R93) according to the wiring diagrams provided with the controller and the sensor's specific documentation. Pay close attention to polarity and terminal designations.
- Verification: After wiring, double-check all connections for security and correctness.
- Power Restoration: Restore power to the system and verify sensor operation through the connected controller.
Note: Specific wiring diagrams and detailed mounting instructions may vary based on the overall system design. Always refer to the complete system documentation for precise installation procedures.
5. Operating Instructions
The A91PAA-2C Thermistor Temperature Duct Sensor operates passively, continuously measuring the ambient air temperature within the duct. It transmits this temperature data as a resistance value to a connected Johnson Controls controller. The controller then interprets this data to execute its programmed functions, such as modulating Series M100 actuators or managing R353 series sequencing modules.
- Temperature Range: The sensor is designed to accurately measure temperatures between 4°C and 32°C (39.2°F and 89.6°F).
- Calibration: The sensor is factory-calibrated. No field calibration is typically required for the sensor itself. Any system calibration or offset adjustments should be performed at the controller level.
- Monitoring: Temperature readings and system responses should be monitored via the connected Johnson Controls controller interface.
6. Maintenance
The Johnson Controls A91PAA-2C sensor is designed for minimal maintenance. However, periodic inspection and cleaning can help ensure continued accurate operation.
- Power Disconnection: Always disconnect power to the sensor and associated equipment before performing any maintenance.
- Cleaning: Periodically inspect the sensor probe and enclosure for dust, debris, or obstructions. Gently clean the exterior with a soft, dry cloth. Do not use abrasive cleaners or solvents.
- Connections: Annually, inspect wiring connections for tightness and signs of corrosion. Re-tighten if necessary.
- Damage Inspection: Check the sensor enclosure and probe for any physical damage. If damage is observed, the sensor may need replacement.
7. Troubleshooting
If the sensor appears to be malfunctioning, consider the following troubleshooting steps:
- No Reading or Incorrect Reading:
- Verify that power is supplied to the connected controller.
- Check all wiring connections between the sensor and the controller for proper termination and continuity.
- Ensure the sensor is correctly configured within the controller's settings.
- Confirm the sensor is installed in an appropriate location within the duct, not affected by external factors.
- If possible, test the sensor's resistance value with a multimeter and compare it to the thermistor's resistance-temperature curve (typically found in the controller's documentation or Johnson Controls technical specifications).
- Intermittent Readings:
- Inspect wiring for loose connections or damaged insulation.
- Check for sources of electromagnetic interference (EMI) near the sensor or wiring.
If troubleshooting steps do not resolve the issue, contact Johnson Controls technical support or a qualified HVAC technician.
8. Specifications
| Specification | Detail |
|---|---|
| Model Number | A91PAA-2C |
| Brand | Johnson Controls |
| Product Type | Thermistor Temperature Duct Sensor |
| Temperature Range | 4°C to 32°C (39.2°F to 89.6°F) |
| Compatibility | Johnson Controls Series R81Q and R93 controllers, Series M100 actuators, R353 series sequencing modules |
| ASIN | B008HOYVQU |
| Manufacturer | Johnson Controls, Inc |
| Package Dimensions | 6 x 6 x 5 inches; 4 Pounds |
9. Warranty and Support
For information regarding the product warranty, technical support, or service, please contact Johnson Controls directly or refer to the warranty documentation provided at the time of purchase. You may also reach out to your authorized distributor or seller for assistance.
Johnson Controls Contact Information: Please visit the official Johnson Controls website for the most current contact details and support resources.
