Compatibility and selection guide
Most wrong-part orders are not caused by a bad part. They are caused by missing system information. Work through these five steps, then paste the worksheet into your inquiry.
Find a part by model keyword or symptom
Trade-buyer search for this site only. Type a system or part keyword, or pick a symptom. Results filter to a category page — they do not check stock, price or a specific model match.
Quick tries:
No match? Use the inquiry page with your system brand, model and existing part details. No order is placed by a search.
Step 1: Identify the system
- System brand and model, from the outdoor and indoor unit nameplates if available.
- System type: air-to-air, air-to-water, or another configuration, if known.
- Winter heating symptom, if that is the job: a house that will not warm up, auxiliary heat that stays on, or a coil that frosts over — start from Thermostats, then Sensors (outdoor and defrost sensors), then Controllers. Gradual warming, or air that feels only mildly warm, alone does not mean a fault; if the house cannot reach its set temperature, follow the Compatibility Guide checklist and send the system brand and model plus the old-part fields through the inquiry page, starting from Thermostats and Sensors. A symptom alone does not prove a category is at fault.
- Defrost split: if a sensor reading looks suspect, start from Sensors; if the defrost cycle never starts or never ends, start from Controllers. A symptom alone does not prove a part is at fault.
- Approximate age and installation context, if that helps identify a generation or revision.
Find the model on the nameplate
Copy the system brand and model exactly as shown on the nameplate, including any suffix letters. For a field-by-field reading, see the Resources nameplate guide.
Step 2: Read the existing part
- Part identification printed on the existing part, if legible.
- Voltage, capacitance, current or temperature range, as applicable to the category.
- Connector type, terminal layout, cable length and mounting dimensions.
- Photos of the nameplate and the existing part, where it is safe to take them.
Step 3: Confirm voltage and refrigerant context
- Supply voltage and phase for the circuit the part serves.
- Refrigerant type used by the system, if relevant to the part or its location.
- Whether auxiliary or emergency heat is involved, for thermostat and control selections.
Step 4: Check what a match still needs
Even with the same headline value, a part can differ in connector, size, mounting or control behaviour. If any item above is missing, say so in your inquiry rather than guessing. Specifications and pricing are confirmed on inquiry, after the system information has been reviewed.
Step 5: Copy this worksheet into your inquiry
On a small screen, swipe sideways to see the full table.
| Field | Your answer |
|---|---|
| System brand / model | |
| System type (air-to-air / air-to-water / other) | |
| Part category | Sensors / Controllers / Capacitors / Contactors / Thermostats / Unsure |
| Existing part identification | |
| Voltage / capacitance / current / range | |
| Connector, terminals, dimensions, mounting | |
| Refrigerant type (if relevant) | |
| Quantity range and delivery region | |
| What has already been checked |
What not to do
- Do not order by appearance alone. Similar-looking parts can have different ratings.
- Do not substitute voltage, capacitance or current ratings without checking system documentation.
- Do not attempt refrigerant or high-voltage work unless you are qualified and local regulations allow it.