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OEM Carrier Transformer 40VA 120V/24V for C4850C48AY03651
Carrier

OEM Carrier Transformer 40VA 120V/24V for C4850C48AY03651

SKU: CARRIE-C4850C48AY03651-TRANSFORMER-HT01BD236 Brand: Carrier
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Texas CMBL #19328542014
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Govt POs Accepted

OEM Carrier 40VA Control Transformer for Model C4850C48AY03651

This is the factory OEM replacement transformer (part# HT01BD236) for the Carrier C4850C48AY03651 packaged unit. The transformer steps down 120V line voltage to the 24V signal required by your thermostat, contactor coil, and all low-voltage control components. When the transformer fails, the entire control circuit goes dark — your thermostat displays nothing, the system won't respond to calls for heating or cooling, and no staging or safety functions operate. Replacing it with the correct OEM part restores reliable, factory-spec control voltage immediately.

  • Specs: 40VA rated | 120V primary / 24V secondary | Class 2 transformer | OEM part number HT01BD236 | Factory-matched for Carrier C4850C48AY03651
  • OEM vs Generic: This OEM unit meets Carrier's exact VA rating and insulation class. Undersized or generic transformers can overheat under full control-circuit load, causing nuisance failures and potential board damage downstream.
  • Install Difficulty: 2/5 — Shut off all power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, wire stripper, multimeter. Label all low-voltage wiring before removing the old transformer to ensure correct reconnection.
  • Warranty: 1-year OEM factory warranty against defects. In stock and ships same business day from our warehouse.

Compatibility: Designed specifically for the Carrier C4850C48AY03651 packaged unit. Always verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate before ordering. Our fitment team is available to confirm compatibility prior to purchase — order with confidence and get your system back online today.

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 C4850C48AY03651?
Yes. This is the factory-specified OEM transformer for the Carrier C4850C48AY03651. 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 C4850C48AY03651?
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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