Same-day shipping before 3PM CST · 35,000+ OEM Parts · Texas CMBL & SAM.gov Registered · Government POs Accepted

Menu

Home Shop All Account Cart
OEM Carrier 40VA 120V to 24V Transformer for C4850C50AJ03661 — Ships Today
Carrier

OEM Carrier 40VA 120V to 24V Transformer for C4850C50AJ03661 — Ships Today

SKU: CARRIE-C4850C50AJ03661-TRANSFORMER-HT01BD236 Brand: Carrier
✓ Guaranteed to fit — or your money back. Terms

OEM Guaranteed

Same-Day Ship

30-Day Returns

Secure Checkout

Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

OEM Carrier 40VA Control Transformer 120V–24V for Model C4850C50AJ03661

This OEM replacement control transformer (part number HT01BD236) is the factory-specified unit for the Carrier C4850C50AJ03661 packaged system. The transformer steps down 120V line voltage to the 24V signal voltage that powers your thermostat, control board, and all low-voltage switching circuits. When this component fails, the entire control circuit goes dead — your thermostat goes blank, the system stops responding to calls for heating or cooling, and no safety controls or relays will operate. It is often the first component to check when a unit appears completely non-functional despite confirmed line voltage at the disconnect.

  • Specs: 40VA rating | Primary: 120VAC | Secondary: 24VAC | OEM part number HT01BD236 | Factory-matched for Carrier C4850C50AJ03661 packaged systems
  • OEM vs Generic: This OEM transformer is wound to exact VA and voltage tolerances specified by Carrier engineering. Undersized or off-tolerance generic transformers can sag under load, causing nuisance lockouts, board resets, and premature contactor coil failure throughout the system.
  • Install difficulty: 2/5 — Disconnect and lock out power before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter, wire nuts. Confirm primary and secondary wiring labels before disconnecting. Always verify 24VAC output at secondary terminals after installation before restoring full system power.
  • Warranty: 1-year OEM factory warranty against defects. In-stock units ship same business day from our warehouse when ordered before cutoff.

Compatibility: Designed specifically for the Carrier C4850C50AJ03661 packaged unit. Verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate before ordering. If you are unsure of fitment, our HVAC parts specialists are available to confirm compatibility before you purchase. Order today and get same-day shipping on this in-stock OEM Carrier control transformer.

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 C4850C50AJ03661 — Ships Today?
Yes. This is the factory-specified OEM transformer for the Carrier C4850C50AJ03661 — Ships Today. 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 C4850C50AJ03661 — Ships Today?
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.
Home Shop Search Account Cart
Fitment Guaranteed
MR
Mike Rivera
HVAC Parts Specialist — Online