Carrier furnace code 32: Low-Heat Pressure Switch Did Not Close or Reopened
Try DIY first, then call a pro
What does code 32 mean on a Carrier furnace? On the two-stage variable-speed control, the low-heat pressure switch did not close within 45 seconds of a call for low heat, or it opened during low heat (a low gas pressure switch opening reads the same). The control shuts down, waits 2 minutes and retries. If the switch opens within 5 minutes after ignition, the next cycle runs in high heat only. Official checklist: vent sizing, plugged condensate drain, low inlet gas pressure (if LGPS used), excessive wind, restricted combustion air, pressure switch wiring, failed or out-of-calibration switches, water or sag in the vent piping, disconnected or obstructed pressure tubing.
Before you touch anything: the six signs that mean stop troubleshooting and call a pro →
Homeowner checks for Carrier furnace code 32
This is a limited outdoor observation check, not a complete furnace repair. If you smell gas or a carbon monoxide alarm sounds, leave the home right away without operating any switches, then call the gas utility or 911 from outside. Never bypass a safety switch or reset the furnace over and over.
- Turn the furnace off
Turn off the furnace at the thermostat and its nearby power switch before checking the vent ends. Keep the furnace cabinet closed.
- Find the vent ends from ground level
Locate the furnace intake and exhaust pipe ends where they leave the house. Only check ends you can see and reach while standing on the ground. Do not climb a ladder or go onto the roof.
- Clear loose snow or leaves by hand
If it is safe to stand there, brush away loose surface snow or leaves from around the openings by hand, without tools. Do not reach into the pipes, chip at ice, or remove or modify any pipe, cap, or screen.
- Stop and call if anything else is wrong
Leave the furnace off and call a technician if you find ice, a nest, a damaged pipe, or anything you cannot clear safely by hand. After clearing only loose surface snow or leaves, restore power and observe one heating cycle. If the code returns, turn the furnace off and arrange service.
Switch pressure-drop testing and vent system sizing. DIY part cost: $30–60 — a pro visit for this class of fault typically runs $150–350.
What causes it (in order of likelihood)
- Plugged condensate drain, or water pooling in a sagging vent pipe DIY-CHECKABLE
- Disconnected or obstructed pressure tubing, or a blocked intake or exhaust termination DIY-CHECKABLE
- Failed or out-of-calibration low-heat pressure switch, or miswired switches TECH
- Vent sizing, excessive wind at the termination, low inlet gas pressure TECH
Parts referenced by this code
Always match parts against your model's parts list — part numbers vary within a series.
Questions about this code
What does code 32 mean on a Carrier furnace?
On the two-stage variable-speed control, the low-heat pressure switch did not close within 45 seconds of a call for low heat, or it opened during low heat (a low gas pressure switch opening reads the same). The control shuts down, waits 2 minutes and retries. If the switch opens within 5 minutes after ignition, the next cycle runs in high heat only. Official checklist: vent sizing, plugged condensate drain, low inlet gas pressure (if LGPS used), excessive wind, restricted combustion air, pressure switch wiring, failed or out-of-calibration switches, water or sag in the vent piping, disconnected or obstructed pressure tubing.
How do I fix Carrier furnace code 32?
From ground level, check the outdoor vent ends and clear loose snow or leaves by hand if safe. Drain, vent piping, tubing, and switch checks need a technician.
How much does it cost to fix Carrier furnace code 32?
The official checklist is long, from a plugged drain to vent sizing or a failed switch. Cost depends on which item a technician finds.
Applies to
58MVP (Series 170/180) · 58MVB · 58UVB
Different Carrier generations use different code maps. If your series isn't listed, don't assume this meaning — check your blower-door label.
Verified against Carrier 58MVP/58MVB/58UVB Troubleshooting Guide (58-06T), p.7/21-22 — “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. If opens during blower on-delay period, blower will come on for the selected blower off-delay. If opens within 5 minutes after ignition the next heating cycle will be restricted to high-heat.”
Verified against Carrier 58MVP/58MVB/58UVB Troubleshooting Guide (58-06T), p.21 — “If the low heat pressure switch LPS does not make within 45 seconds after a call for heat is initiated the variable speed furnace control starts flashing status code 32, shuts unit down, waits 2 minutes, stops flashing status code 32, and restarts the heating cycle.”
Verified against Carrier 58MVB Service and Maintenance Instructions (58MVB-2SM), p.17 — “Check for: Proper vent sizing. Low inlet gas pressure (if LGPS used). Restricted combustion air supply. Disconnected or obstructed pressure tubing. Defective or miswired pressure switches. Excessive wind. Plugged condensate drain. Water in vent piping, possible sagging pipe”
Last verified 2026-09-05 · page updated 2026-10-03 · how we verify
Related Carrier furnace codes
These codes use the same status led — two-stage variable-speed (58mvp / 58mvb / 58uvb) system.