What are the specs for this Transformer?

The correct replacement for Carrier model PY3GNAA30040AA 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 PY3GNAA30040AA.

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 208/240V–24V for PY3GNAA30040AA

Name: OEM Carrier Transformer 40VA 208/240V–24V for PY3GNAA30040AA
Brand: Carrier
SKU: CARRIE-PY3GNAA30040AA-TRANSFORMER-HT01BD209
Price: 47.25 USD
Availability: InStock

SKU: CARRIE-PY3GNAA30040AA-TRANSFORMER-HT01BD209 Brand: Carrier

✓ Guaranteed to fit PY3GNAA30040AA — or your money back. Terms

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OEM Carrier Control Transformer 40VA 208/240V to 24V for Model PY3GNAA30040AA

The Carrier HT01BD209 is the factory-specified 40VA step-down transformer for the PY3GNAA30040AA HVAC system. This transformer is the heartbeat of the low-voltage control circuit — it steps 208/240V line voltage down to the 24V AC signal that powers your thermostat, contactor coil, and control board. When it fails, the entire system goes dark: no thermostat response, no contactor click, no blower activation. If your system is completely unresponsive despite confirmed line voltage at the unit, a failed transformer is one of the first components to check.

Specs: Input 208/240V | Output 24V | 40VA rated | 50/60Hz dual frequency | OEM part number HT01BD209
OEM vs Generic: This is the genuine Carrier OEM transformer, wound to exact VA and voltage tolerances. Generic aftermarket units frequently run outside ±5% tolerance, which can cause nuisance tripped low-voltage fuses, erratic board behavior, or premature contactor coil failure.
Install difficulty: 2/5 — Always shut off all power (line and low-voltage) before beginning. Photograph existing wiring connections before disconnecting. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter (to verify 24V output post-install). Insulate all terminals after reassembly.
Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Direct OEM replacement for Carrier model PY3GNAA30040AA. Verify your unit's data plate shows 208/240V primary control circuit before ordering. Our fitment team is available to confirm compatibility before you purchase — ships same day when ordered before 3PM EST.

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

OEM Carrier Transformer 40VA 208...

$47.25

Frequently Asked Questions

Does this Transformer fit my Carrier PY3GNAA30040AA?

Yes. This is the factory-specified OEM transformer for the Carrier PY3GNAA30040AA. 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 PY3GNAA30040AA?

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 208/240V–24V for PY3GNAA30040AA

OEM Carrier Control Transformer 40VA 208/240V to 24V for Model PY3GNAA30040AA

Shipping Information

Return Policy

Frequently Asked Questions