Bathroom vent

[clev]

Behind the commode is a vent, that I thought was a return air vent to the AC's. After removing the grill, I saw an open space and even saw the sliding stairway door. Still thinking it was return air, I turned on both AC's but there was no return air suction. There is a large grill over the pantry double doors, but again no return suction. What is the purpose of these 2 grills?

[CheapRV]

It sounds like the grills you're referring to may not be return air vents for the AC, but rather passive air circulation or ventilation openings. Here are a few possibilities for the purpose of those grills:

Ventilation for Airflow Between Compartments: RVs are designed with passive vents to allow for airflow between different areas, particularly to equalize pressure and help distribute air from the AC or heater. The grill behind the commode and the one over the pantry doors could be intended for that purpose, allowing air to circulate between spaces even if they aren't directly connected to an AC return.

Access to Plumbing or Electrical Components: Sometimes, grills in RVs are placed to allow easy access to plumbing, wiring, or other systems behind walls. The open space you noticed behind the commode might be part of the access to those systems.

Heat Ventilation: In some cases, grills like the ones over the pantry may be designed to allow heat to escape from appliances or electronics housed in cabinets or compartments. This passive venting prevents overheating in areas where heat buildup could be an issue.

If these grills are not producing any airflow or suction when the AC is on, they are most likely not part of the AC system's return air ducts. Instead, they likely serve as passive ventilation or access points to improve airflow throughout your RV. You can check your RV's manual or consult the manufacturer for more specific details on what those particular grills are intended for in your model.

[clev]

Thank you, Cheap. Definitely not return air nor access points. My wife checked the one behind the commode. The one over the pantry is ceiling level, fixed, and not removable.

[Cummins12V98]

Down low behind the toilet mine has a bout 10 x 6" metal grill and yes it a return air for the furnace.

[clev]

Thank you, Cummins. Mine is like yours, and I had not thought of the furnace. I'll check it today. But behind the grill is just the space between the walls, not what I think of for a return air vent. Also, why would DRV put a return air anywhere near a commode; the nastiest part of the RV?