HVACopediaCarrier · Furnace
23.2 Secondary pressure switch stuck closed
What the control is telling you
The secondary (inducer housing) pressure switch (HPS) is closed when it should be open. The control checks both switches are open before starting the inducer.
Applies to: Carrier 59SC6A
Likely causes
- Stuck switch contacts
- Jumpered or miswired switch
- Pressure tube problem
Test and repair steps
- With the inducer off, check continuity across the HPS: it must be open (normally-open switch).
- Check for jumpers or miswiring.
- Inspect switch tubing for kinks or water.
- Replace the switch if it stays closed with no inducer running.
Settings for these units
Save it for the next call
Star this code in the HVACopedia app and keep the whole library on your phone for jobs with no signal.
Source: Carrier 59SC6A Installation, Start-up, Operating and Service Instructions, Fig. 60 Service Label p.54; Fig. 61 Wiring p.56; Sequence of Operation p.68. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.