Johnson Controls A99BB-300 Silicon Sensor

For high-accuracy temperature sensing in commercial refrigeration and HVAC systems, the Johnson Controls A99BB-300 Silicon Sensor is a reliable industry standard. This passive PTC silicon sensor features a Positive Temperature Coefficient, where resistance increases linearly with temperature, providing a reference resistance of 1035 ohms at 77?F (25?C). Equipped with a 9.75ft PVC cable, this sensor is designed for high-moisture environments with a splashproof stainless steel bulb that prevents corrosion in walk-in coolers and freezers. Engineered for precision, it maintains an accuracy of ?0.9?F within the critical range of 5 to 167?F. The -40 to 212?F operating range makes it a versatile choice for defrost termination and condenser fan cycling applications. It is fully compatible with Johnson Controls Penn A419, System 450, and MR/MS series controllers, ensuring seamless integration into existing control loops without the need for complex recalibration in the field.

Key Benefits

• Broad Compatibility: Works natively with Penn A419, A421, and System 450 controls.
• Extended Lead Capacity: High resistance variation per degree allows for lead extensions up to 800 feet with minimal signal degradation.
• Durable Construction: The stainless steel sensing probe offers professional-grade protection against corrosive refrigeration environments.
• Pre-Calibrated Precision: Each PTC thermistor is calibrated to a standard curve for consistent "plug-and-play" performance.

Common Questions

Can the A99BB-300 sensor be used in condensing environments?
Yes, the A99B series is designed to operate in 0 to 100% relative humidity, making it ideal for reach-in coolers and defrost termination where condensation is frequent.

What is the difference between the A99BB and A99BC models?
The A99BB-300 utilizes a PVC cable rated up to 212?F, whereas the A99BC series uses high-temperature silicon cabling for applications exceeding that thermal limit.

How do I verify if the sensor is functioning correctly?
Using an ohmmeter, check the resistance across the leads. At 77?F, you should see approximately 1035 ohms. Significant deviation from the published temperature-resistance curve indicates the need for a replacement.

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.