SPNO-SPNC 24V RELAY

What it is

• Brand family: MARS / Supco / Hartland Controls
• Type: Heavy-duty HVAC fan relay
• Function:
  • uses 24V control signal to switch line-voltage loads
  • controls blower motors, condenser fans, or auxiliary circuits
  • replaces older WR/Essex/RBM Type 184 relays

Key specs

• Coil voltage: 24 VAC
• Contact rating: ~18A @ 120/240/277V (varies by load type)
• Contact form: SPNO / SPNC (1 Form A / 1 Form B)
• Mounting: flange / tab mount
• Terminals: 1/4" quick connect

How it fits your system

This is part of your HVAC control relay family, alongside:

• D-90340 (general purpose switching relay)
• fan relays (903-series variants)
• contactor-style switching devices

Bottom line

• ✔ Real standardized HVAC relay
• ✔ Multiple manufacturers cross-reference the same number (90380)
• ✔ Widely used in air handlers, furnaces, and AC systems
• ❌ Not a single OEM-exclusive part (it’s a universal cross-reference relay code