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OEM Carrier Control Transformer 40VA 208/240V–24V for PY4GPAA42090AA
Carrier

OEM Carrier Control Transformer 40VA 208/240V–24V for PY4GPAA42090AA

SKU: CARRIE-PY4GPAA42090AA-TRANSFORMER-HT01BD209 Brand: Carrier
✓ Guaranteed to fit PY4GPAA42090AA — or your money back. Terms

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Texas CMBL #19328542014
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OEM Carrier Control Transformer 40VA 208/240V to 24V — HT01BD209 for Model PY4GPAA42090AA

This OEM Carrier control transformer (part number HT01BD209) is the factory-specified replacement for the Carrier PY4GPAA42090AA packaged unit. The transformer steps down 208/240V line voltage to the 24V DC signal required to power your thermostat, control board, contactor coil, and all low-voltage safety circuits. When this transformer fails — due to age, a shorted control wire, or a wiring fault — the result is a completely unresponsive system: the thermostat goes dark, the unit won't respond to any calls for heating or cooling, and the contactor will not pull in.

  • Specs: 208/240V Primary | 24V Secondary | 40VA Rating | 50/60 Hz | Factory OEM part number HT01BD209 | Also cross-references 4000A46E07AE28
  • OEM vs Generic: This genuine Carrier OEM transformer is wound to exact factory VA and voltage tolerances. Aftermarket units often underperform under full 24V load, causing nuisance lockouts or premature failure of downstream control boards.
  • Install Difficulty: 2/5 — Shut off all power at the disconnect and breaker before starting. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to verify 24V output post-install). Label and photograph all low-voltage wiring before disconnecting. The transformer mounts via two screws inside the control box; swap wire-for-wire and restore power to test.
  • Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Direct OEM replacement for Carrier model PY4GPAA42090AA. Also replaces superseded Carrier part numbers HT01BD207, HT01CN232, and 9076-00. Verify your unit's control circuit voltage (208/240V primary, 24V secondary) on the data plate before ordering. Our fitment team is available to confirm compatibility before you buy — order with confidence.

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 PY4GPAA42090AA?
Yes. This is the factory-specified OEM transformer for the Carrier PY4GPAA42090AA. 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 PY4GPAA42090AA?
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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