Carrier Furnace Code 32
WarningShown as: 3 short flashes, 2 long flashes
Low-heat pressure switch did not close on a call for low heat, or opened during low heat. If it opens within 5 minutes after ignition, the next heating cycle is forced to high heat.
Manual wording: “32 LOW-HEAT PRESSURE SWITCH DID NOT CLOSE OR REOPENED - Indicates the low-heat pressure switch input failed to close on a call for low-heat, or opened during low-heat.”
Documented for: 58MVP, 58UVB and other variable-speed two-stage Carrier furnaces
Likely causes, most common first
- Improper vent sizing
- Plugged condensate drain
- Low inlet gas pressure (if a low gas pressure switch is used)
- Excessive wind
- Restricted combustion air supply
- Improper pressure switch wiring
- Failed or out-of-calibration pressure switch
- Water in the vent piping from a sagging pipe
- Disconnected or obstructed pressure tubing
What you can safely check yourself
- Check outdoor intake and exhaust pipe terminations for snow, ice, or debris
- Check the condensate drain and trap for a clog
- Replace a dirty air filter
When to call a technician
Vent sizing, sagging vent pipe, and pressure switch calibration are all technician diagnostics. Do not bypass the switch.
A Carrier furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Troubleshooting Guide - Variable Speed, Two-Stage Gas Furnaces (Form 58-06T) (Carrier, 58MVP, 58UVB and other Carrier variable-speed two-stage gas furnaces (replaces 58MVP-10SM)) · checked 2026-08-25