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OEM Carrier Transformer 40VA 120V-24V for C4850C50AJ03551
Carrier

OEM Carrier Transformer 40VA 120V-24V for C4850C50AJ03551

SKU: CARRIE-C4850C50AJ03551-TRANSFORMER-HT01BD236 Brand: Carrier
✓ Guaranteed to fit C4850C50AJ03551 — or your money back. Terms

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Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

OEM Carrier 40VA Control Transformer HT01BD236 for Model C4850C50AJ03551

This is the OEM factory-specified control transformer (part# HT01BD236) for the Carrier C4850C50AJ03551 packaged unit. The transformer steps down 120V line voltage to the 24V signal required by your thermostat, control board, contactor coil, and all low-voltage safety circuits. When the transformer fails, the entire control circuit goes dead — the thermostat goes blank, the system refuses any call for heating or cooling, and no fault codes are generated because the board itself has no power. Replacing this part is often the first diagnostic step when a unit appears completely unresponsive.

  • Specs: 40VA rated | Primary: 120VAC | Secondary: 24VAC | OEM part number HT01BD236 | Factory-matched impedance and insulation class for Carrier packaged equipment
  • OEM vs Generic: OEM transformers are wound to exact VA and voltage tolerances required by the factory control board. Undersized or off-tolerance aftermarket units can overheat under load, trip thermal protection, or deliver unstable 24V that causes nuisance faults and board damage over time.
  • Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before servicing. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter. Confirm 0V at both primary terminals before disconnecting wires. Label or photograph all low-voltage wiring before removal.
  • Warranty: 1-year OEM factory warranty against defects in materials and workmanship. In-stock and ships same business day from our climate-controlled warehouse.

Compatibility: Designed as a direct OEM replacement for the Carrier C4850C50AJ03551 packaged unit. Verify primary voltage (120V) and VA rating on your unit's wiring diagram or data plate before ordering. Our fitment team is available to confirm compatibility before you buy — no guesswork required. Order today and receive same-day shipping on all in-stock parts.

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 $99
  • 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 C4850C50AJ03551?
Yes. This is the factory-specified OEM transformer for the Carrier C4850C50AJ03551. 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 C4850C50AJ03551?
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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