Packaged terminal air conditioner (PTAC) under a window with its control door open, showing the set temperature and mode buttons
5 components covered

Field manual · Air Conditioner

Friedrich PDE / PDH digital PTACs, R-32 SG chassis (2022+): quick sheet with F/E/A/H codes

Covers: Friedrich standard-chassis digital PTACs on R-32 covered by service manual 94142000: PDE (cool with electric heat) and PDH (heat pump) in 7,000-15,000 BTU/h sizes, e.g. PDE07K3SGR3, PDE07R3SGR3, PDE09K3SGR3, PDE09R3SGR3 and the guide example PDH09K3SGR3 (12,000-15,000 BTU/h electric-heat and heat-pump sizes are also in the manual). Model guide: P = PTAC, D = digital, E or H = cool only with electric heat / heat pump, two digits = approximate cooling BTU/h, voltage K = 230/208 V or R = 265 V, heater digit 2 = 2.5 kW, 3 = 3.5 kW, 5 = 5 kW, then SG series and R3 for R-32. Serial guide: first two digits = year (22 = 2022 ... 25 = 2025), next two = month, then a manufacturing location letter and a 5-digit sequence starting at 00001 each month (e.g. 1712M00001). Older R-410A PDE/PDH units may use a different code set. Search terms: PDH09K3SGR3, PDE09K3SGR3, Friedrich PTAC F0, Friedrich PTAC A2, Friedrich PTAC U5.

Single sourceBrands: Friedrich5 components

This PTAC has a logic PCB, a separate power PCB with current-sensing (CT) loops, a display PCB and a status LED on the main board. Major faults shut the unit down and show a code on the two-digit display; minor self-correcting conditions are only flashed on the status LED (visible with the front removed). Codes cover sensors (F1-F4, FJ), protections (FP, F0, H3, E5), heater circuit faults (A0, A2, A4, C7) and current imbalance (U5).

Safety first

  • Unplug before opening; capacitors and PCBs hold charge.
  • R-32 is mildly flammable; refrigerant work is blocked and goes to an EPA 608-certified technician.

How it works

Sensors: indoor ambient 15 kOhm at 77 °F; indoor coil, outdoor ambient, condenser coil and discharge sensors 20 kOhm at 77 °F (Friedrich table).

Cooling freeze protection (status LED 5 flashes): compressor and outdoor fan stop, indoor fan runs; resumes when the indoor coil reads 40 °F or more for 2 minutes.

Heat pump frost prevention (7 flashes): compressor and outdoor fan stop; electric heat after 15 s if heat is called; compressor available again after the sensor reads 40 °F or more for 10 minutes.

Heating high-temperature protection of the evaporator (8 flashes): compressor and outdoor fan stop, electric heat enabled after 15 s; returns when the coil reads 126 °F or less for 2 minutes.

FP low-temperature protection: room below 40 °F continuously; unit runs electric heat only until the room reaches 50 °F.

Components & tests

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Official manufacturer documentation

Always confirm values against the tech sheet for the exact model.

OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work. © 2026 OnCall Tech. Original content; not a reproduction of any manufacturer document.Generic part photos (not of this brand): Packaged terminal air conditioner (PTAC) under a window with its control door open, showing the set temperature and mode buttons by Central Avenue, CC BY 4.0

Diagnostic guides for this appliance

Guide · Air Conditioner

PTAC not cooling (fan runs, air not cold)

Most PTAC no-cool calls are airflow (filter, coils), a wrong control setting or a failed compressor start component. Rule those out before suspecting the sealed system.

6 steps ~60 minmoderate
Guide · Air Conditioner

PTAC not heating (electric heat or heat pump)

PTACs heat with electric strip heat, a heat pump, or both. Heat pump models switch to strip heat in cold weather. Check settings, then the heater element and its limits, then the reversing valve.

5 steps ~60 minmoderate
Guide · Air Conditioner

PTAC error codes: how to read and clear them

Most PTAC brands store fault codes that can be shown with a button combination on the control (for example, on GE Zoneline (2019 technical service guide) you hold FAN and the red AUX button together while the unit is OFF, and AUX clears stored faults; other models use other sequences, so use the model's tech sheet). Read the active code, fix the cause, then clear it.

4 steps ~20 mineasy

Other air conditioners manuals

Manual · Air Conditioner

Carrier Infinity Greenspeed 24VNA6 air conditioner and 25VNA4 heat pump (variable speed): quick sheet

Carrier Infinity Greenspeed Intelligence variable-speed outdoor units: 24VNA6 air conditioner (up to 26 SEER) and 25VNA4 heat pump (up to 24 SEER, up to 13 HSPF), 2-5 ton. Nomenclature from the service manual: 24 = AC, 25 = HP; V = variable speed; N = Infinity series; A = Puron (R-410A); 6 / 4 = SEER tier; two digits = nominal capacity (e.g. 36 = 36,000 BTU/h); voltage digit 3 = 208/230-1; compressor ID 4 = variable-speed scroll, 5 = variable-speed rotary. Serial format: week + year + plant letter + sequence (e.g. 0118E00001). Other 24VNA families (24VNA0, 24VNA9) use different software and code lists.

5 components4 common failuresCarrier
Manual · Air Conditioner

Trane XV20i / XV18 variable-speed outdoor units (4TTV0 AC, 4TWV0 heat pump, ComfortLink II): quick sheet

Trane variable-speed TruComfort / ComfortLink II communicating outdoor units: 4TTV0 air conditioners (XV20i family, e.g. 4TTV0024A1000C, 4TTV0036, 4TTV0048, 4TTV0060, 4TTV0061) and 4TWV0 heat pumps (Service Facts 4T-V0-SF). They use an Integrated Variable Speed Control (IVSC) board and a Communicating Display Assembly (CDA) in the outdoor unit. Distributor listings note several 4TTV0 revisions; confirm the full model on the nameplate before ordering parts. Single-stage XR14/XR16 units are on a separate sheet.

4 components3 common failuresTrane
Manual · Air Conditioner

Lennox XC21 air conditioner and XP21 heat pump (Dave Lennox Signature, iComfort-enabled): quick sheet

Lennox XC21 (air conditioner, service literature Corp. 1007-L2) and XP21 (heat pump, Corp. 1031-L7), 2, 3, 4 and 5 ton, R-410A, expansion valve indoor coils only. Both use an A175 main control (outdoor control part number 101798-xx) that works in communicating (iComfort) or conventional 24 V mode, plus a separate fan motor control. The XP21 literature describes a two-stage scroll compressor; the 2018 XC21 literature describes the compressor as one-stage while the same control section covers two-stage units, so confirm staging on the nameplate. For ML14XC1/EL16XC1 single-stage units see the separate sheet.

4 components3 common failuresLennox
Friedrich PDE / PDH digital PTACs, R-32 SG chassis (2022+): quick sheet with F/E/A/H codes · OnCall Tech