Warning: This guide is a high-level summary. Follow the official manufacturer manual and all local electrical/safety codes. Use qualified installers for electrical and mechanical work.
Even with the Crawford CDM9 950 installation manual in hand, mistakes happen. Here is a troubleshooting guide derived from the manual’s appendix:
| Error Display | Probable Cause | Manual’s Fix |
| :--- | :--- | :--- |
| S.ERR | Sensor broken or wired backwards | Check polarity (thermocouple: red = negative, yellow/white = positive). |
| UUUU | Input over-range (>10% above max) | Sensor short circuit (for RTD) or wrong Lin.H scaling. |
| LLLL | Input under-range | Thermocouple reversed or sensor disconnected. |
| AL1 flashing | Alarm 1 active | Normal operation; check if relay is wired correctly. |
| Erratic PV | Electrical noise | Move signal wires away from power wires. Check shield grounding. |
| Output LED on, but load cold | Blown fuse or no power to load | Check external 2A fuse. Verify the relay contacts are closing (measure continuity). | crawford cdm9 950 installation manual
Warning from the manual: Do not auto-tune on an empty chamber (no product load) if you will later run a full load. The PID values will be too aggressive. Always auto-tune under typical load conditions.
| Symptom | Likely Cause | Solution | |---------|--------------|----------| | Display blank | Missing 24V control power | Check terminals +24V and COM | | Motor hums but no rotation | Incorrect U/V/W phase order | Swap any two output phases | | Overvoltage fault | Deceleration too fast | Increase decel time or add braking resistor | Warning: This guide is a high-level summary
The CDM9 950 includes an advanced auto-tune algorithm. The manual outlines two methods: standard AT and adaptive AT.
For installations using Modbus RTU (RS-485), the manual dedicates a technical appendix. The CDM9 950 uses a 2-wire half-duplex connection. Ambient Conditions: -10°C to +50°C (14°F to 122°F);
If you are using the CDM9 950 to fire an SCR power regulator: