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FANs 125, 121, 930, 930.5

Product/Technical Bulletin A99

Issue Date 0699

The A99B Series Temperature Sensors are passive

PTC (Positive Temperature Coefficient) sensors.

The A99B sensors are splashproof and are

designed to measure temperature in a variety of

refrigeration applications. Several accessories allow

easy tailoring of the temperature sensor to various

mounting configurations.

Applications include temperature sensing for

freezers and coolers, as well as in defrost

termination sensing, space and return air

temperature sensing, and condenser fan cycling.

Figure 1: A99B Temperature Sensors

Features and Benefits

Part No. 24-7664-1636, Rev. — www.johnsoncontrols.com

Code No. LIT-125186

 Variety of Lead Lengths Encompasses most application requirements

and simplifies wiring sensors

 Assortment of Mounting

Hardware Available

Provides configuration for many

applications—customizable

 Very Accurate Sensing

Element

Provides excellent performance in a wide

variety of control applications

 Stainless Steel Sensor Bulb Allows use in more applications than other

types of bulbs; no corrosion

A99B Series Temperature Sensors

Summary of content (8 pages)

PAGE 1
FANs 125, 121, 930, 930.5 Product/Technical Bulletin A99 Issue Date 0699 A99B Series Temperature Sensors The A99B Series Temperature Sensors are passive PTC (Positive Temperature Coefficient) sensors. The A99B sensors are splashproof and are designed to measure temperature in a variety of refrigeration applications. Several accessories allow easy tailoring of the temperature sensor to various mounting configurations.
PAGE 2
A pplication Overview IMPORTANT: All A99B Series Sensors are designed for use only with operating controls. Where an operating control failure would result in personal injury and/or loss of property, it is the responsibility of the installer to add devices (safety, limit controls) or systems (alarm, supervisory) that protect against, or warn of, control failure.
PAGE 3
D imensions O peration The A99B sensor incorporates a PTC silicon sensing element whose resistance increases with an increase in temperature. The sensor has a reference resistance of 1035 ohms at 77°F (25°C). Each element is calibrated according to a standard graph, as shown in Table 2. 1/4 (6) 2 (50) The A99B series sensors are typically used with Johnson Controls/PENN System 350™ controls, MR Defrost controls MS Multi-Stage controls, and A419 Electronic Temperature controls.
PAGE 4
Mounting Using an Immersion Well Mounting with a PVC Enclosure 1. Select the mounting location in the pipe line. A 1/2 in., 14 NPT, opening is required to properly install the immersion well (WEL11A601R). The pipe’s diameter must be greater than the length of the well probe. The PVC enclosure can be mounted in a variety of ways. See Figure 6 for mounting dimensions.
PAGE 5
W iring ! C heckout Procedure WARNING: Shock Hazard. Disconnect all power to the controller that the sensor is connected to before wiring or servicing. Troubleshooting For wiring, follow the instructions below: • Make sure all wiring conforms to the National Electric Code and local regulations. • Run high and low voltage wiring in separate conduits. For applications in critical industrial environments, use a sensor with a shielded cable (A99BA).
PAGE 6
Temperature (°F) Table 2: Resistance vs.
PAGE 7
R epairs and Replacement Field repairs or calibration must not be made. For replacement sensors, contact your nearest Johnson Controls/PENN representative. When contacting the supplier, state the model number of the sensor. The sensor model is printed on the yellow label wrapped around the sensor cable.
PAGE 8
S pecifications Product Sensing Range Reference Resistance Accuracy Sensor Construction A99B Series Silicon Temperature Sensors Model A99BA and A99BB: -40 to 212°F (-40 to 100°C) Model A99BC: -40 to 248°F (-40 to 120°C) 1035 ohms at 77°F (25°C) 0.9°F ( 0.5°C) between 5 and 167°F (-15 and 75°C). See Figure 12 for accuracy outside of this range.