American Standard / Trane Error 175.01: Suction Pressure Range Cutout / Limp Mode (Meaning, Causes, Fixes)

What the code means

American Standard and Trane are sister brands, and their communicating variable-speed outdoor units share the same alert code list. Trane's System Alert Guide (August 2020) lists ERR.175.01 as SUCTION PRESSURE RANGE CUTOUT / LIMP MODE. For outdoor software version 3.X or higher, it describes the problem as the compressor being temporarily disabled because the suction pressure transducer is out of range on the high end (above approx. 375 psig), with the compressor not allowed to operate until pressure drops below approx. 365 psig. The possible cause it gives is a suction pressure transducer that has failed or is out of range, and it adds that if the outdoor temperature is above 112°F you should let it cool below 110°F to see whether the transducer comes back in range and clears the alert. For outdoor software 1.0 and 2.0, the same code means the compressor ran at a fixed speed because of high or low superheat in heating mode for an extended time; the guide's checks are the suction temperature sensor's location, mounting and insulation, the suction sensor's calibration, the pressure transducer's calibration, and updating the outdoor unit's software if the alert keeps repeating. Trane's ComfortLink II alert table lists CL2.175.01 (LIMP MODE LO) as a Critical alert where a lost sensor reading inhibits compressor operation, pointing to faulted sensors (dome, suction, ambient, or the indoor sensor with the expansion valve in safe mode). Nearby codes in the same family: 175.00 is the general limp-along mode (compressor speed fixed to a constant value), 175.03 is limp mode from low superheat, 175.02 is excessive low superheat after repeated 175.03 alerts, and 174.00 is a suction pressure sensor fault.

Likely causes

• Very high outdoor temperatures. Trane specifically says that above 112°F the transducer can read out of range, and the alert may clear once it's below 110°F.
• A failed or out-of-range suction pressure transducer. This is the cause Trane lists for software 3.X and newer.
• High or low superheat in heating mode on units with older outdoor software (1.0 and 2.0), which pushes the compressor into fixed-speed limp mode.
• A suction temperature sensor that's loose, poorly insulated, mounted in the wrong spot or out of calibration.
• Outdated outdoor unit software. Trane recommends updating to the latest outdoor software when this alert repeats.
• Refrigerant pressure or airflow problems. Trane's table flags these as possibilities for the limp-mode family of alerts; a dirty outdoor coil is general background that can raise pressures.

Safe DIY checks

1. Note the outdoor temperature and the time the alert showed up. If it was an extreme heat spike, give the unit time to cool and see if the alert clears on its own, as Trane describes.
2. Check the thermostat's alert history for companion codes such as 174.00, 175.00, 175.02 or 175.03. Write them all down for the technician.
3. With power off at the outdoor disconnect, look for anything blocking airflow around the outdoor unit (leaves, cottonwood, grass clippings, items stacked against it) and clear it. Gently rinse a dirty coil with a garden hose from the inside out if you can do so safely; never use a pressure washer.
4. Replace a dirty indoor air filter and make sure supply and return vents aren't blocked, since poor airflow affects system pressures.
5. Don't keep resetting power over and over to force the compressor to run. If the alert keeps returning in normal weather, call a technician.

Parts that commonly fix it

Always match the part number to your exact model.

Related codes

• 180.02 Trane HVAC System 180.02
• 67.06 Trane HVAC System 67.06
• 106.00 Trane HVAC System 106.00
• 126.00 Trane HVAC System 126.00
• 156 Trane HVAC System 156

All Trane codes →

Sources

1. Trane System Alert Guide (Aug 2020), p. 33: ERR.175.01 Suction Pressure Range Cutout / Limp Mode (software 3.X: transducer above approx. 375 psig, compressor off until below approx. 365 psig, let ambient above 112°F cool below 110°F; software 1.0/2.0: fixed speed from high or low superheat in heating, sensor and transducer checks, software update); ERR.175.00, 175.02, 175.03 (distributor-hosted copy)
2. Trane ComfortLink II alert codes table: CL2.175.01 Critical, LIMP MODE LO, loss of sensor reading, compressor operation inhibited; CL2.174.00 and CL2.175.00 (distributor-hosted copy)