Dash Ventilation failure

[AJS]

I have a 2015 Precept (35UN). The dash ventilation does not change modes.
I am wondering where the vacuum reservoir is hidden as a first place to check. Any other suggestions as to potential problems would be greatly appreciated.
Any diagrams or vacuum line schematics also appreciated.

[RogerR]

My old car had the same problem and the dealer put a vacuum pump on a line and found a broken line hidden behind the engine from the leak making a noise.


Not an RV problem, just a truck dealer type problem if you want it fixed, maybe an AC guy could help also.

[Drv]

My Parents 2014 Precept had the same problem when unit was new. If you are willing and able, you may want pull Center console holding radio and check all the vacuum lines coming in and out through firewall. Ours had a mess and some were kinked. If it has been working and now stopped you might put vacuum pump on the vacuum diaphragm actuator that controls HVAC damper. This was the cause of our problem. Ours was located in Engine bay firewall on passenger side. Silver canister with vacuum line attached should be actuator. Our A/C unit was built by Victory I believe? They may have changed vendors for 2015's

[Rice1951]

I had an issue with the selector knob for directing the air flow to dash, floor or defrost vents. Would not change regardless of position. Jayco replaced it when I brought it to Middlebury for other warranty work.
It could be a bad switch or maybe something as simple as a wiring connection. You see these same knobs in every gasser MH regardless of brand so I believe they are supplied by Ford. If you didn’t want to tackle it yourself you could probably take it to a truck repair shop that works on the F53 chassis. Good luck.

[AJS]

Thanks, good info. I found a vacuum resevoir mounted to passenger fender. It has red and black vacuum lines attached to it. Will check resevoir for leaks, then check lines.

[AJS]

Thanks John.

[Dbrown]

There is also a recall for the dash fan motor fuse. The fuse may have blown. Make sure the recall has been done.