Bryant 355MAV Error Code 32: Low-Heat Pressure Switch Did Not Close or Reopened
What Does Code 32 Mean?
Status code 32 on the Bryant 355MAV means the low-heat pressure switch input failed to close on a call for low-heat, or opened during low-heat operation. If it opens during the blower on-delay period, the blower runs for the selected off-delay; if it opens within 5 minutes after ignition, the next heating cycle is restricted to high-heat only.
Because the 355MAV is a two-stage furnace, it has separate pressure switches for low-heat and high-heat. The low-heat switch senses the gentler draft of low-speed firing, so it is more sensitive to partial restrictions that a stronger high-heat draft might overcome. That is why a marginal problem can show up as code 32 while high-heat still works.
This is also a condensing furnace, which produces water whenever it runs. The most common cause of code 32 is a plugged condensate drain: when the drain backs up, water collects in the inducer housing and kills the low draft the switch needs. Improper vent sizing, restricted combustion air, water sagging in the vent piping, or a failed pressure switch are other causes. Note that code 43 (Low-Heat Pressure Switch Open While High-Heat Pressure Switch Is Closed) is a related but different fault — a disagreement between the two switches rather than the low-heat switch simply failing to close. These checks are technician work on this model.
What You'll Notice
- The furnace shuts down on low-heat, or refuses to start a low-heat cycle
- The furnace runs only on high-heat and skips its quieter low-heat stage
- Water may be visible backing up or pooling near the furnace base
- The status LED flashes code 32 (three short flashes, two long flashes)
- Short cycling or no heat during mild weather when the furnace would normally use low-heat
Common Causes
How This Is Diagnosed
A technician checks the condensate drain and trap first, since a plugged drain is the most common cause on this condensing furnace, then inspects the vent piping for sagging sections holding water. The low-heat draft pressure is measured against the switch's set point to see whether the inducer develops enough suction at low speed.
If drainage and venting are clear and draft is adequate, the low-heat pressure switch and its tubing are tested for correct operation and calibration. Accessing the drain, inducer, and switch and interpreting draft readings require tools and training, so this is handled by a qualified technician.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- Code 32 persists and the condensate drain, trap, or vent piping needs service
- The furnace stays stuck in high-heat-only mode
- Water keeps pooling around the furnace base
- The inducer sounds weak or runs unevenly at low speed
- The low-heat pressure switch or its calibration is suspected
Frequently Asked Questions
Why is my Bryant 355MAV stuck on high heat?
If the low-heat pressure switch opens within 5 minutes of ignition, the board restricts the next cycle to high-heat only — reported as code 32. Clearing the underlying cause, often a plugged condensate drain, lets it resume normal two-stage operation.
How is code 32 different from code 43?
Code 32 is the low-heat pressure switch failing to close or reopening on its own. Code 43 is a disagreement — the low-heat switch is open while the high-heat switch is closed. They involve the same low-heat switch but describe different fault conditions.
Does a condensing furnace really clog its own drain?
Yes. The 355MAV produces condensate every time it fires, and that drain can slowly clog with sediment or biofilm. A backed-up drain is the most common trigger for code 32 and is a routine thing for a technician to clear.
Sources
✓ Verified against manufacturer service manual — March 2026