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OEM Carrier Transformer 40VA 120V/24V for C48A503551
Carrier

OEM Carrier Transformer 40VA 120V/24V for C48A503551

SKU: CARRIE-C48A503551-TRANSFORMER-HT01BD236 Brand: Carrier

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Texas CMBL #19328542014
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Govt POs Accepted

OEM Carrier 40VA Control Transformer HT01BD236 for Model C48A503551

This is the factory OEM replacement control transformer (part number HT01BD236) for the Carrier C48A503551 packaged unit. The transformer steps down 120V line voltage to the 24V signal used by your thermostat, contactor coil, and control board. When it fails, the entire control circuit goes dead — your thermostat goes blank, the system won't respond to calls for heating or cooling, and no safety or operating sequence can begin. It is one of the most overlooked yet critical components in any HVAC system.

  • Specs: 40VA capacity | 120V primary / 24V secondary | Class 2 transformer | OEM part number HT01BD236 | Factory-matched for Carrier C48A503551 packaged units
  • OEM vs Generic: This OEM transformer is wound to exact Carrier specifications, ensuring stable 24V output under full control circuit load. Generic alternatives often run undervoltage during peak demand, causing erratic contactor chatter, nuisance lockouts, and premature board failure.
  • Install difficulty: 2/5 — Shut off all power before servicing. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, wire stripper, multimeter. Label and photograph existing wiring before disconnecting. Typical replacement time is 20–30 minutes.
  • Warranty: 1-year OEM factory warranty against defects in materials and workmanship. Ships same business day from our NationalHVACParts.com warehouse.

Compatibility: Designed as a direct OEM replacement for Carrier C48A503551 packaged units. Always verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate or wiring diagram before ordering. Have questions about fitment? Our HVAC parts specialists confirm compatibility before you buy — order with confidence and get back up and running fast.

Shipping Information

  • Orders placed before 3PM CST ship same business day
  • Standard delivery: 2-5 business days
  • Express shipping available at checkout
  • Free shipping on orders over $75
  • Tracking number emailed upon shipment

Return Policy

  • 30-day returns on unused parts in original packaging
  • Electrical parts (capacitors, contactors, control boards) are final sale once installed
  • Email info@nationalhvacparts.com to initiate a return
  • Refunds processed within 5-7 business days

Frequently Asked Questions

Does this Transformer fit my Carrier C48A503551?
Yes. This is the factory-specified OEM transformer for the Carrier C48A503551. It is a direct drop-in replacement that fits without modification. Always verify the model number on your equipment nameplate before ordering.
How do I replace the transformer on my Carrier C48A503551?
Difficulty: Medium (30–45 min)
Step 1: Turn off breaker. Step 2: Photo wiring connections. Step 3: Disconnect wires from old transformer. Step 4: Remove mounting hardware. Step 5: Install new transformer, reconnect wires matching voltage ratings. Step 6: Verify 24V output with multimeter.
My thermostat has no power. What failed?
Thermostat with no display = failed 24V transformer (or blown control board fuse). Check the 3A/5A fuse on the control board first ($1–$5 fix). If fuse is good but no 24V output from transformer, replace transformer.
Is this transformer compatible with Bryant or Payne too?
Many Carrier parts are cross-compatible with Bryant and Payne since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across brand labels with different model numbers. To verify: check your Bryant or Payne equipment service manual for cross-compatible part numbers, or email info@nationalhvacparts.com with your model number.
Should I use OEM or aftermarket for my Carrier transformer?
OEM recommended for reliability and warranty compatibility. OEM parts match exact factory specifications for proper fit, performance, and safety. While aftermarket alternatives cost less upfront, the risk of improper fit and reduced lifespan usually makes OEM the better value long-term.
How fast does National HVAC Parts ship?
Orders placed before 3:00 PM CST ship the same business day. Standard delivery is 2–5 business days anywhere in the continental United States. Express shipping available at checkout. We ship from Houston, TX to all 50 states. 30-day return policy on all parts.
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Mike Rivera
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