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OEM Carrier Transformer 40VA 120V/24V for C50A503551
Carrier

OEM Carrier Transformer 40VA 120V/24V for C50A503551

SKU: CARRIE-C50A503551-TRANSFORMER-HT01BD236 Brand: Carrier

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Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

OEM Carrier Control Transformer 40VA for Model C50A503551

This OEM replacement transformer (part number HT01BD236) is the factory-specified step-down transformer for the Carrier C50A503551 commercial rooftop unit. The transformer converts 120V line voltage to the 24V AC signal that powers your thermostat, control board, contactor coils, and all low-voltage control components. When this part fails, the entire control circuit goes dark — the thermostat loses power, the system will not respond to calls for heating or cooling, and nothing works at all despite the unit receiving line voltage.

  • Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | Replaces OEM part number HT01BD236 | Factory-matched output for reliable low-voltage circuit performance
  • OEM vs Generic: This is a genuine Carrier OEM transformer wound to exact VA and voltage tolerances. Generic transformers may be undersized in VA rating, causing overheating, nuisance tripping of the built-in thermal fuse, or premature control board failure from unstable voltage output.
  • Install difficulty: 2/5 — Disconnect all power before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter, wire nuts or spade connectors. Verify 24V output at secondary terminals with a multimeter after installation before restoring power to the full system.
  • Warranty: 1-year OEM factory warranty against defects. In-stock and ships same business day from our warehouse.

Compatibility: Engineered specifically for the Carrier C50A503551 commercial rooftop packaged unit. Always verify the VA rating and primary/secondary voltages against your unit's wiring diagram and data plate before ordering. Not sure it fits? Our HVAC parts specialists will confirm fitment before you buy — contact us today and get your system back online fast with same-day shipping.

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 C50A503551?
Yes. This is the factory-specified OEM transformer for the Carrier C50A503551. 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 C50A503551?
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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