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OEM Carrier 40VA Transformer 24V Control Circuit for C4850C48AY02561
Carrier

OEM Carrier 40VA Transformer 24V Control Circuit for C4850C48AY02561

SKU: CARRIE-C4850C48AY02561-TRANSFORMER-HT01BD236 Brand: Carrier
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Texas CMBL #19328542014
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OEM Carrier 40VA Control Transformer HT01BD236 for Model C4850C48AY02561

This OEM control transformer (part# HT01BD236) is the factory-specified replacement for the Carrier C4850C48AY02561 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 it fails, the entire control circuit goes dark — the thermostat goes blank, the system ignores all calls for heating or cooling, and nothing responds. If you've ruled out a blown fuse and tripped breaker, a failed transformer is the next most likely culprit.

  • Specs: 40VA rated | 120V primary / 24V secondary | Factory-matched output tolerance | Direct OEM replacement for part# HT01BD236
  • OEM vs Generic: OEM transformers from Carrier are wound to exact VA and voltage tolerances, preventing under-voltage brownouts that damage control boards and contactor coils. Generic units frequently run low under load, causing intermittent lockouts and premature board failure.
  • Install Difficulty: 2/5 — Shut off power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade terminals. Label all low-voltage wires before disconnecting. Verify 24V output with a multimeter before buttoning up the panel.
  • Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed as a direct OEM replacement for the Carrier C4850C48AY02561 packaged unit. Confirm your existing transformer's VA rating and primary/secondary voltages on the unit data plate before ordering. Not sure it fits? Our HVAC parts specialists verify fitment before you buy — reach out before placing your order.

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 C4850C48AY02561?
Yes. This is the factory-specified OEM transformer for the Carrier C4850C48AY02561. 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 C4850C48AY02561?
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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