Johnson Controls A99BB-500 Temperature Sensor

The Johnson Controls A99BB-500 is a high-precision PTC silicon temperature sensor engineered for demanding commercial refrigeration and HVACR applications. Designed with a 1035 ohm reference resistance at 77?F, this passive sensor provides exceptional linearity and accuracy, specifically maintaining a tolerance of ±0.9?F between 5?F and 167?F. The A99BB-500C features a 16-3/8 foot (5-meter) PVC lead cable and a durable stainless steel sensing bulb, making it an ideal choice for defrost termination sensing, walk-in cooler monitoring, and condenser fan cycling. As part of the Penn A99 series, it is fully compatible with System 450 controllers, A419 and A421 electronic controls, and MR/MS series modules. This sensor is built to handle operating environments ranging from -40?F to 212?F, ensuring reliable performance in both process heating and cooling stages. Its calibrated PTC element allow for lead extension up to 800 feet with negligible effect on signal integrity, providing field technicians with maximum installation flexibility without the need for complex recalibration.

Key Benefits

• Wide Operating Range: rated for environmental extremes from -40?F to 212?F (-40?C to 100?C), suitable for freezers and high-temp glass display cases.
• System Compatibility: seamless integration with Johnson Controls System 450, System 350, and A421 digital temperature controllers.
• Robust Construction: features a stainless steel sensor bulb that resists corrosion in high-humidity and splash-prone refrigeration environments.
• Extended Lead Capacity: the 22 AWG PVC cable can be extended significantly (up to 800 feet) due to the high resistance variation of the PTC element.
• High Accuracy: factory-calibrated to a standard resistance-temperature curve, ensuring precise HVACR temperature monitoring across the entire range.

Common Questions

• Can I extend the cable on the A99BB-500? Yes, you can extend the leads up to 800 feet using standard 22 AWG wire. However, remember to account for the additional lead resistance (approximately 0.035 ohms per meter) in your controller settings if high-precision offset is required.
• Is this sensor waterproof for immersion applications? While the sensor is splashproof and moisture-resistant for typical refrigeration use, for direct immersion in liquids, it is recommended to use a thermowell (immersion well) to protect the probe and prevent long-term degradation.
• What is the difference between the A99BA and A99BB models? The A99BB-500 uses a standard PVC cable, whereas the A99BA series typically includes a shielded cable for environments with high electromagnetic interference (EMI).

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.