RecPro Air Conditioner: “E4”
warning RV air conditioner error codes
What it means
The system detects that it is running but not producing the expected cooling effect.
Most likely causes
- Low or lost refrigerant charge most likely
- Compressor not engaging common
- Dirty filter or evaporator coil reducing cooling performance common
- Outdoor coil/condenser airflow restriction less common
Safe checks you can do yourself
- Check and clean the return-air filter and confirm the evaporator (indoor) coil is not blocked.
- Confirm the cooling mode is selected and the set temperature is below the current room temperature.
- With power off, inspect the rooftop condenser coil for debris.
How to reset / clear E4
- Turn the unit off at the remote/plenum control.
- Remove power at the breaker for about a minute, then restore and restart in cooling mode.
When to call a technician
If filters and airflow are fine but cooling is still weak and E4 persists, a technician should check refrigerant charge and the compressor circuit.
Applies to
RecPro RP-AC3501 · RecPro RP-AC3800 · RecPro RP-AC3400 · RecPro H3400 / A3400 / A3401 · RecPro A3501 / A3800 / T3500 (ducted)
FAQ
What does RecPro Air Conditioner code "E4" mean?
The system detects that it is running but not producing the expected cooling effect.
How do I reset RecPro Air Conditioner E4?
Turn the unit off at the remote/plenum control. Remove power at the breaker for about a minute, then restore and restart in cooling mode.
What is the most common cause of E4 on a RecPro Air Conditioner?
The most likely cause is low or lost refrigerant charge.
Related · RecPro air conditioner
The outdoor ambient temperature sensor is reading out of ran… E9
The room temperature sensor located in the wall pad (wall co…
Sources
- RP-AC3501 / RP-AC3800 Ducted Air-Conditioning System Owner's Manual — No cooling effect E4 (RecPro)
- RP-AC3400 Low Profile Air Conditioner Owner's Manual (H3400/A3400/A3401) — No cooling effect E4 (RecPro)
Note: RecPro AC units are rebranded Houghton-type units, so the RecPro and Houghton code tables match (E0-E5, E8, E9).
● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.