Denso Air Conditioner Error Code AS

The AS code on a Denso air conditioner indicates a condensate pump problem. Specifically, the relay board has detected that the J8 input, which monitors the optional condensate pump, has shifted to an open state. This means the pump is damaged, has failed, or has lost its electrical connection to the relay board. The unit will not operate normally until the pump issue is resolved.

Resetting alone will not permanently clear the AS code if the underlying pump problem has not been fixed. The reset procedure, pressing ON/OFF and HI/LO simultaneously for 5 seconds, is intended to be performed after the condensate pump has been repaired or replaced. If the fault condition still exists at the J8 input, the code will return immediately or shortly after the reset.

Repair costs vary depending on what has failed. A simple line clearing or wiring fix may involve only a service call fee, typically in the range of $75 to $150. Replacing a condensate pump unit generally costs between $150 and $400 including parts and labor, depending on the pump model and local labor rates. Relay board repairs or replacements can be more expensive, potentially ranging from $300 to $600 or more.

Some causes of the AS code are within reach of a knowledgeable DIYer, such as clearing a blocked condensate line, draining a full pump reservoir, or reseating a loose wiring connection at the J8 relay board input. However, replacing a failed pump motor or diagnosing internal relay board faults typically requires a qualified technician. After any repair, the system must be reset by pressing the ON/OFF and HI/LO buttons simultaneously for 5 seconds.

No, you should not attempt to operate the unit while the AS code is active. A non-functioning condensate pump can allow water to accumulate and overflow, potentially causing water damage to ceilings, walls, or floors. The system is designed to shut down when this fault is detected specifically to prevent that damage. Address the pump issue before resuming operation.