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 Transformer 40VA 120V to 24V for C4850C50AK03661 | National HVAC Parts
Carrier

OEM Carrier Transformer 40VA 120V to 24V for C4850C50AK03661 | National HVAC Parts

SKU: CARRIE-C4850C50AK03661-TRANSFORMER-HT01BD236 Brand: Carrier

OEM Guaranteed

Same-Day Ship

30-Day Returns

Secure Checkout

Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

OEM Carrier Transformer 40VA 120V–24V for Model C4850C50AK03661

This is the OEM factory-replacement transformer (part number HT01BD236) for the Carrier C4850C50AK03661 packaged unit. The transformer steps down line voltage (120V) to the 24V signal voltage that powers your thermostat, control board, contactor coil, and all low-voltage control circuits. When this transformer fails, the entire control circuit goes dead — the thermostat displays nothing, the system won't respond to any call for heating or cooling, and no safety controls can operate. It is often the first component to check when a unit shows zero low-voltage activity.

  • Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | OEM part number HT01BD236 | Screw-terminal or quick-connect leads (verify against your existing unit)
  • OEM vs Generic: OEM transformers are wound and insulated to Carrier's exact VA and impedance specifications. Undersized or off-tolerance generic transformers can overheat, blow the 3A fuse on the control board, or damage downstream components — making a $30 repair into a $150+ problem.
  • Install difficulty: 2/5 — Disconnect power at the breaker and confirm zero voltage with a multimeter before touching any terminals. Tools needed: flathead and Phillips screwdrivers, multimeter, wire stripper. Photograph all wire connections before disconnecting. Replace the inline fuse if blown.
  • Warranty: 1-year OEM factory warranty. Orders placed before cutoff ship same business day from our warehouse.

Compatibility: Designed specifically for the Carrier C4850C50AK03661 commercial/residential packaged unit. Always verify your existing transformer's VA rating and lead configuration against your unit's wiring diagram before ordering. Our parts specialists are available to confirm fitment — contact us before you order if you have any questions.

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 C4850C50AK03661 | National HVAC Parts?
Yes. This is the factory-specified OEM transformer for the Carrier C4850C50AK03661 | National HVAC Parts. 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 C4850C50AK03661 | National HVAC Parts?
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