Technical specifications - PENN Controls - A421ABD - A421AED - Electronic Temperature Control - A421 Off‐Cycle Defrost Model

A421 Series Electronic Temperature Controls with Off-Cycle Defrost Installation Guide

Product name
A421 Off‐Cycle Defrost Model
Document type
Installation Guide
Document revision
Revision date
Table 1. A421 Series Electronic Temperature Controls Technical Specifications
Specification Description
Power consumption 1.8 VA maximum
Supply power 110/120 VAC or 208/230/240 VAC, 50/60 Hz
Ambient conditions Operating: Type 1 models: -40°F to 150°F (-40°C to 66°C), 0% to 95% RH noncondensing

Type 4X models: -40°F to 140°F (-40°C to 60°C), 0 to 95% RH noncondensing

Shipping and storage: All models: -40°F to 185°F (-40°C to 85°C), 0% to 95% RH noncondensing

Temperature control range -40°F to 212°F or -40°C to 100°C
Input signal 1,035 ohm at 77°F (25°C) for A99 PTC Temperature Sensors
Accuracy Combined accuracy of A421 Control and A99 sensor: ±2°F (±1°C) between 5°F and 167°F (-15°C and 75°C); diverging to ±3°F (±2°C) at -40°F (-40°C) and ±3°F (±2°C) at 212°F (100°C)
Sensor offset range ±5ºF or ±3ºC
Enclosure material Type 1, IP20 high-impact thermoplastic or

Note: Type 4X, IP66 watertight, corrosion-resistant, high-impact thermoplastic


North America: cULus Listed; UL 60730, File E27734, Vol. 1; FCC Compliant to CFR47, Part 15, Subpart B, Class B

Industry Canada (IC) Compliant to Canadian ICES-003, Class B limits

Europe: CE Mark – Johnson Controls declares that this product is in compliance with the essential requirements and other relevant provisions of the EMC Directive; Low Voltage Directive.


Australia and New Zealand: RCM, Australia/NZ Emissions Compliant

Table 2. A421 Temperature Control Output Relay Contacts electrical ratings
Agency and file UL 60730 and EN 60730
Applied AC voltage at 50/60 Hz 120 VAC 208 VAC 240 VAC
Horsepower LC/LNO (LC/LNC) 1 (0.25) 1 (0.3) 1 (0.5)
Full load amperes LC/LNO (LC/LNC) 16 (5.8) 9.2 (4) 8 (4.9)
Locked rotor amperes LC/LNO (LC/LNC) 96 (34.8) 55.2 (24) 48 (29.4)
Resistive amperes LC/LNO (LC/LNC) 15 (10) 10 (10) 10 (10)
Pilot duty VA LC/LNO (LC/LNC) 125 (125) 125 (125) 125 (125)
Table 3. UL conformity declaration information
Information Description
Purpose of control Sensing control / operating control
Construction of control Electronic independently mounted control
Number of cycles 30,000 cycles
Method of mounting control Mounting screws or DIN rail
Type 1 or type 2 action Type 1.B (Micro-disconnection)
External pollution situation All models: A421 [ ] B: Pollution degree 3

All models: A421 [ ] E: Pollution degree 4

Internal pollution situation Pollution degree 2
Heat and fire resistance category D
Rated impulse voltage 4,000 V
Ball pressure temperature 128°C
Cover screw torque requirements instruction All models: A421 [ ] E: To maintain type 4X / IP66 rating, tighten enclosure screws to 10–12 in·lb
Table 4. A99B Series Positive Temperature Coefficient Sensors Technical Specifications
Specification Description
Sensing range1 Type A99BA and A99BB: -40°F to 212°F (-40°C to 100°C)

Type A99BC: -40°F to 248°F (-40°C to 120°C)

Reference resistance 1,035 ohms at 77°F (25°C) and 855 ohms at 32°F (0°C)
Accuracy 0.9°F (0.5°C) between 5°F and 167°F (-15°C and 57°C). Refer to the A99B Series Temperature Sensors Product/Technical Bulletin (LIT-125186) for accuracy rating outside of this temperature range.
Sensor construction Probe: Stainless steel
Sensor cable sheath Type A99BA: Shielded PVC cable

Type A99BB: PVC cable

Type A99BC: High temperature silicon cable

Wire gauge 22 AWG
Ambient operating conditions

Type A99BA and A99BB: -40°F to 212°F (-40°C to 100°C); 0% to 100% RH, condensing

Type A99BC: -40°F to 248°F (-40°C to 120°C); 0% to 100% RH, condensing

Ambient storage conditions

Type A99BA and A99BB: -40°F to 221°F (-40°C to 105°C); 0% to 100% RH, condensing

Type A99BC: -40°F to 266°F (-40°C to 130°C); 0% to 100% RH, condensing

Shipping weight 1.4 oz (41 g) for 6 1/2 ft (2 m) sensor
Accessories See Table 3

The performance specifications are nominal and conform to acceptable industry standards. For application at conditions beyond these specifications Johnson Controls shall not be liable for damages resulting from misapplication or misuse of its products.

1 When any A99 Series Temperature Sensor is connected to a standard A421 Control model, the range of displayed temperature values is -40ºF to 212ºF or -40ºC to 100ºC.