What are the specs for this Transformer?

The correct replacement for Carrier model C4850C48AY04161 is this exact part. It is the factory-specified replacement with exact OEM specifications. Using a part with different specifications can cause equipment damage or void your warranty. You can verify this by checking the data plate on your Carrier equipment which lists the model number C4850C48AY04161.

Is this transformer compatible with Bryant or Payne systems too?

Many Carrier parts are cross-compatible with Bryant and Payne systems since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across multiple brand labels with different model numbers. To verify cross-compatibility, check your Bryant or Payne equipment service manual for cross-compatible part numbers, or contact info@nationalhvacparts.com with your model number for confirmation.

Carrier

OEM Carrier Transformer 40VA 120V/24V for C4850C48AY04161

Name: OEM Carrier Transformer 40VA 120V/24V for C4850C48AY04161
Brand: Carrier
SKU: CARRIE-C4850C48AY04161-TRANSFORMER-HT01BD236
Price: 47.25 USD
Availability: InStock

SKU: CARRIE-C4850C48AY04161-TRANSFORMER-HT01BD236 Brand: Carrier

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OEM Carrier 40VA Control Transformer for Model C4850C48AY04161

This OEM step-down transformer (part# HT01BD236) is the factory-specified replacement for the Carrier C4850C48AY04161 packaged unit. The transformer converts 120V line voltage down to the 24V signal required by your thermostat, control board, contactor coil, and all low-voltage control circuits. When it fails, the entire control circuit goes dead — your thermostat goes blank, the system won't respond to any call for heating or cooling, and nothing happens when you cycle the unit. A failed transformer is often misdiagnosed as a bad control board, making this a critical first diagnostic step.

Specs: 40VA rating | 120V primary / 24V secondary | Class 2 current-limited | OEM part number HT01BD236 | Factory-matched output tolerance for reliable low-voltage control
OEM vs Generic: This OEM transformer is wound and insulated to Carrier's exact factory specification. Generic transformers frequently under-deliver rated VA, causing nuisance tripping of the internal thermal fuse and erratic control board behavior — especially under high contactor coil demand.
Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, wire nuts or terminal connectors, multimeter to confirm 24V output after installation. Label all wires before disconnecting the old unit.
Warranty: 1-year OEM factory warranty against defects. In-stock and ships same business day from our warehouse when ordered before 3PM local time.

Compatibility: Engineered specifically for the Carrier C4850C48AY04161 packaged unit. Always verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate or wiring diagram before ordering. If your system is tripping the transformer repeatedly, inspect for shorted low-voltage wiring before replacing — a wiring short will take out a new transformer just as fast. Our parts team is available to confirm fitment before you order. Order now and receive same-day shipping!

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

OEM Carrier Transformer 40VA 120...

$47.25

Frequently Asked Questions

Does this Transformer fit my Carrier C4850C48AY04161?

Yes. This is the factory-specified OEM transformer for the Carrier C4850C48AY04161. 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 C4850C48AY04161?

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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OEM Carrier Transformer 40VA 120V/24V for C4850C48AY04161

OEM Carrier 40VA Control Transformer for Model C4850C48AY04161

Shipping Information

Return Policy

Frequently Asked Questions