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OEM Carrier Transformer 40VA 120V/24V for C48A804064
Carrier

OEM Carrier Transformer 40VA 120V/24V for C48A804064

SKU: CARRIE-C48A804064-TRANSFORMER-HT01BD702 Brand: Carrier

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Texas CMBL #19328542014
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Govt POs Accepted

OEM Carrier 40VA Control Transformer HT01BD702 for Model C48A804064

This OEM step-down transformer is the factory-specified replacement for the Carrier C48A804064 packaged unit. The transformer converts 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 dead — the thermostat loses power, the system won't respond to any call for heating or cooling, and no fault codes appear because there's no voltage to generate them. If your unit is completely unresponsive and you've ruled out a blown fuse or tripped breaker, a failed transformer is the most common cause.

  • Specs: 40VA rating | Primary: 120V | Secondary: 24V | OEM part number HT01BD702 | Factory-matched electrical tolerance for reliable low-voltage output
  • OEM vs Generic: OEM transformers are wound and insulated to Carrier's exact VA and voltage specifications. Undersized or off-spec generic units can overheat, blow the 3A control fuse repeatedly, or deliver unstable 24V that causes erratic thermostat and board behavior.
  • Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before starting. Tools needed: flathead and Phillips screwdrivers, multimeter, needle-nose pliers. Photograph existing wiring connections before removal. Verify 24V output with a multimeter after installation before closing the cabinet.
  • Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Engineered for the Carrier C48A804064 packaged unit. Confirm your existing transformer's VA rating and primary/secondary voltages on the unit data plate or transformer label before ordering. Cross-reference OEM part number HT01BD702 for guaranteed fitment. Have questions about compatibility? Our HVAC parts specialists verify fitment before you order — reach out before you buy.

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 C48A804064?
Yes. This is the factory-specified OEM transformer for the Carrier C48A804064. 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 C48A804064?
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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