True Refrigerator Error Code do: Door Open Alarm
Do on a True cabinet with an LAE control is the door open alarm. Close the door firmly and clear anything keeping it from seating. If do stays on with the door shut, a technician should check the gasket, hinges and door switch.
Low: an operator alert; the cabinet keeps cooling.
- Code
- Do
- Maker
- True
- Equipment
- Reach-in refrigerators
- Applies to
- LAE control
What does True error code Do mean?
Do is the door open alarm on True cabinets with an LAE control, such as the T-49-HC. It appears when the door has been open longer than the control allows. The cabinet keeps running, and the alarm is meant to keep warm kitchen air out of the box. It clears by itself when the door is shut. The control relies on a door switch to know where the door is, so the alarm is only as accurate as that switch and the way the door seats. If do stays on with the door closed, either the door is not seating or the switch is not telling the control it has closed. A paper strip drawn along the gasket will show a loose spot where the seal is weak.
Affected models and control systems
True cabinets with an LAE control, such as the T-49-HC.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- Do on the display
- An audible alarm while the door is open
- do staying on after the door is closed
- Warm air or condensation at the door edge
Possible causes
Listed in True's documentation
- A worn gasket or sagging hinge that keeps the LAE cabinet door from seating
- A door switch stuck or out of position, so do never clears
- A loose door switch wire that breaks the signal to the LAE control
- Stored stock pressing on the door so it sits slightly open
Other likely causes — what usually sits behind error code Do on this control. A technician confirms which one it is before any part is replaced.
- A door switch magnet shifted after a door adjustment
- Moisture in the switch connector corroding the contacts
- A latch that no longer pulls the door tight
Safe checks before calling for service
- Close the door firmly.
- Look for pans, boxes or bottles keeping the door from seating.
- Press any button to quiet the alarm if it continues.
- Run a sheet of paper along the gasket to find a loose spot.
- If do stays on with the door shut, note whether the light and fans behave as if the door is open.
How a technician diagnoses error code Do
- Check the door fit and latch with the door closed.
- Inspect the gasket for gaps and compression.
- Check hinges for sag and adjust.
- Watch the door switch input at the LAE control while opening and closing the door.
- Test the switch and wiring with a meter for a break or short.
- Replace the switch or gasket after the test.
- The door switch signal is carried by low-voltage wiring behind the control panel.
- Re-hanging a heavy door and resetting the seal takes the right hardware and alignment.
- A leaking gasket forces the compressor to run longer and shortens its life.
How error code Do differs from similar codes
The Dixell version of this alarm shows as dA; do is the LAE display for the same condition.
Technical reference
- Document
- Commercial Refrigeration General Control Guide TEC_TM_001 Rev C, LAE p.110 Display Code Definitions
- Edition
- TEC_TM_001 | REV. C | EN, 09/3/2025, P#811072
- Models / control
- LAE control
- Section
- Electronic Control (with Display) - Display Code Definitions: Carel p. 74, Danfoss ERC/ETC p. 87, Dixell p. 96, LAE p. 110
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related True reach-in refrigerator error codes
Will do clear on its own?
Yes, as soon as the control sees the door shut.
Does do mean my cabinet stopped cooling?
No. It keeps running; the alarm is there to keep warm air out.
Why does it stay on after I close the door?
The door may not be seating, or the switch is not signaling that it closed.
Need help with True error code Do?
A technician confirms the cause on site and gives you the price in writing before any work starts.