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OEM Carrier Transformer 40VA 120V to 24V for C48A402751 | National HVAC Parts
Carrier

OEM Carrier Transformer 40VA 120V to 24V for C48A402751 | National HVAC Parts

SKU: CARRIE-C48A402751-TRANSFORMER-HT01BD236 Brand: Carrier
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OEM Carrier Transformer 40VA 120V/24V for Model C48A402751

This OEM step-down transformer (part number HT01BD236) is the factory-specified replacement for the Carrier C48A402751 packaged unit. The control transformer steps down line voltage from 120V to 24V to power the entire low-voltage control circuit — including the thermostat, contactor coil, and control board. When it fails, nothing responds: the thermostat goes dark, relays won't energize, and the system is completely unresponsive despite power being present at the unit.

  • Specs: 40VA rating | 120V primary / 24V secondary | Factory-matched impedance and thermal protection | Replaces OEM part number HT01BD236
  • OEM vs Generic: This OEM unit is wound to Carrier's exact VA rating and insulation class. Undersized or off-spec generic transformers can overheat, trip the internal fuse, or fail to sustain the 24V circuit under full relay load — causing intermittent lockouts that are difficult to diagnose.
  • Install difficulty: 2/5 — Disconnect all power before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade terminals. Always confirm 24V output with a meter before reassembling the control panel. Check for shorted wiring in the low-voltage circuit before installing the new transformer to avoid repeat failure.
  • Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier C48A402751 packaged unit. Verify the transformer VA rating and primary/secondary voltages on your unit's wiring diagram or data plate before ordering. If you're unsure of fitment, our HVAC parts specialists are available to confirm compatibility before you buy — order with confidence and get back up and running fast.

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 C48A402751 | National HVAC Parts?
Yes. This is the factory-specified OEM transformer for the Carrier C48A402751 | 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 C48A402751 | 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.
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Mike Rivera
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