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OEM Carrier Transformer 40VA 120V/24V for C48A803564
Carrier

OEM Carrier Transformer 40VA 120V/24V for C48A803564

SKU: CARRIE-C48A803564-TRANSFORMER-HT01BD702 Brand: Carrier

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Texas CMBL #19328542014
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OEM Carrier Control Transformer 40VA 120V/24V for Model C48A803564

This OEM Carrier transformer (part number HT01BD702) is the factory-specified replacement for the C48A803564 packaged unit. The transformer steps down line voltage from 120V to 24V to power the entire low-voltage control circuit — including the thermostat, contactor coil, gas valve, and control board. When the transformer fails, nothing in the system responds: the thermostat goes blank, the unit won't call for heat or cooling, and you may find a blown fuse on the control board. If your system is completely unresponsive, the transformer is one of the first components to test.

  • Specs: 40VA rating | 120V primary / 24V secondary | OEM part number HT01BD702 | Factory-matched output for stable control voltage
  • OEM vs Generic: This OEM transformer is wound to exact VA and voltage tolerances required by Carrier. Generic transformers frequently run under-rated VA, causing voltage sag under load — which leads to nuisance lockouts, contactor chatter, and premature control board failure.
  • Install difficulty: 2/5 — Disconnect power at the breaker and verify voltage is absent before starting. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade connectors. Label all wiring before removal and confirm primary/secondary connections match your existing wiring diagram.
  • Warranty: 1-year OEM factory warranty. In-stock units ship the same business day from our warehouse.

Compatibility: Designed for the Carrier C48A803564 packaged unit. Verify your existing transformer's VA rating, primary voltage, and secondary voltage on the unit's wiring diagram or data plate before ordering. Our fitment team is available to confirm compatibility before you buy — same-day shipping on all in-stock orders.

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 C48A803564?
Yes. This is the factory-specified OEM transformer for the Carrier C48A803564. 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 C48A803564?
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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