The Johnson Controls A99BB-25 Temperature Sensor is a high-accuracy PTC silicon sensor designed for precision monitoring in commercial refrigeration and HVAC applications. This passive Positive Temperature Coefficient sensing element provides a reference resistance of 1,035 ohms at 77?F (25?C), ensuring reliable data for system 450 controls, A419, and A421 series modules. The sensor is constructed with a stainless steel bulb and a 9 3/4-inch PVC cable, offering a wide sensing range of -40 to 212?F. Its splashproof design makes it an ideal fit for evaporator coil temperature sensing, defrost termination, and condenser fan cycling. By utilizing a calibrated silicon element, the A99BB-25 minimizes the need for field recalibration when replacing existing PENN temperature sensors in established refrigeration circuits. For contractors managing complex setups, the lead wire can be extended up to 800 feet with 22 AWG wire while maintaining technical signal integrity. Key Benefits Precision Calibrated PTC Element: Delivers exceptional accuracy of 0.9?F (0.5?C) within the critical range of 5 to 167?F. Durable Stainless Steel Probe: Resists corrosion in high-moisture environments, suitable for walk-in coolers and freezers. Extensive Compatibility: Seamlessly integrates with Johnson Controls System 350, System 27, and MR/MS series digital controllers. Versatile Application: Engineered for space, return air, and liquid temperature sensing via optional immersion wells. Common Questions How do I verify the sensor's health in the field? Use an ohmmeter to check the resistance across the leads. At 32?F (0?C), you should see approximately 855 ohms; at 77?F (25?C), it should read 1,035 ohms. Can the 22 AWG PVC lead wire be lengthened? Yes, the lead length may be extended up to 800 feet. Ensure all connections are moisture-tight to prevent resistance fluctuations. Is this sensor suitable for high-humidity environments? The A99BB-25 features a splashproof construction and is rated for 0 to 100% RH condensing environments within its operating temperature range. Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
