Goodman Furnace: Auxiliary limit control (location and purpose)
Auxiliary limit control (location and purpose) on a Goodman furnace: On these select 90% and 95% furnaces there are two auxiliary limits on the blower housing, one on each side. They are there for the horizontal and counterflow installs, where a failed blower would let heat build up with nothing to carry it away. When I see one open it usually means the blower quit or the power dropped while the burners were lit. They also open on a power loss mid-cycle. They are good for both horizontal right and horizontal left, so you do not move them around.
Applies to: Select 90% and 95% furnaces
Common causes of auxiliary limit control (location and purpose)
- Main blower failure in horizontal or counterflow installations
- Loss of power while the furnace is firing
- Restricted airflow overheating the blower housing
- Loose connection at the limit terminals
How to fix auxiliary limit control (location and purpose): step by step
- Locate the two auxiliary limits on the blower housing, one on each side
- The auxiliary limit works in both horizontal right and horizontal left installations and does not need to be relocated for airflow direction
- Test the auxiliary limit per the procedure in the manual that follows this section, power off and at room temperature
- If one is open, check the blower and filter before resetting it
- Do not bypass either limit, they protect the cabinet and wiring
If the unit shows an error code, look it up: Goodman Furnace codes
Source: Goodman GMVC96 service and troubleshooting manual, p. 48. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.