Johnson Controls
A421ABG-02C
A421 Series • HVAC Controller
Quick Info
Type
HVAC
Application
Refrigeration/HVAC
Probe Inputs
1
Relay Outputs
1
Panel Size
- mm
Electronic temperature control for refrigeration with SPDT output
Technical Specifications
Display & Interface
| Display Type | LED |
| Display Digits | 3 |
| Buttons | 3 |
Power Supply
| Voltage | 120-240V AC |
| Voltage Range | 100-277V AC |
| Frequency | 50/60Hz |
| Power Consumption | 5VA |
Sensor Inputs
| Probe Inputs | 1 |
| Probe Type | NTC 10K (A99 Series) |
| Temp Range | -40 to 99°C |
| Accuracy | ±±0.5°C |
Relay Outputs
| Relay Outputs | 1 |
| Relay Rating | 24A/120VAC FLA, 144A/120VAC LRA |
Physical
| Panel Size | - mm |
| Depth | - mm |
| IP Rating | IP30 |
Operating Conditions
| Operating Temp | -40 to 65°C |
Wiring Terminals
| Terminal | Function | Type | Wire Color |
|---|---|---|---|
| AC Line | Power |
power
|
|
| AC Neutral | Power |
power
|
|
| Relay Common | Output |
relay
|
|
| Relay N.O. | Output |
relay
|
|
| Relay N.C. | Output |
relay
|
|
| Sensor + | Input |
sensor
|
|
| Sensor - | Input |
sensor
|
Important: Always disconnect power before wiring. Verify terminal numbers with the actual controller label before connecting.
Parameter Settings
| Code | Parameter | Range | Default | Description |
|---|---|---|---|---|
| SP | Set Point | -40~99 | 4 °C | |
| dIF | Differential | 0.5~30 | 2 °C | |
| ASC | Anti-Short Cycle | 0~12 | 5 min | |
| OFS | Offset | -9~9 | 0 °C | |
| HA | High Alarm | SP~99 | OFF | |
| LA | Low Alarm | -40~SP | OFF |
Error Codes
E1