Air condition box

[STEAMBOAT99]

I need to know where to begin looking I have a 2007 Itasca Ellipse DP had new air compressor, new dryer and new line ran from rear to front because hose was leaking. Coming back north this month everything was great cool air it was really nice until we stopped for the night. Next morning as we were traveling it was a little chilly so I turn the heat on everything fine until windshield started to fog a little do to the cool outside so I turned the defrost on worked great then when it was time for air I turned air on and its cold but will only come out the defrost vents for windshield just like the door is not opened and closing not sure where to start all help appreciated. The only thing I see up front is one arm that works I guess a door I can move it with my hand but air still come out the defrost. Thanks STEAMBOAT JIM

[Skip426]

Can you see the name " Evans " anywhere molded into the HVAC system box?

Evans/ Tempcon is one of the dash A/C suppliers to the RV industry and the condition you describe is common .
Defrost is the default for the dash system , and all other modes require vacuum that is produced by a small 12v electric pump on diesel motorhomes.
If Evans is your system , either the vacuum pump has failed or there is a problem with the vacuum getting to the dash mounted control panel.

Just in case your system is Evans here's a picture of their usual vacuum pump and a diagram of the vacuum distribution.
Check that the vacuum pump has 12v power when the engine is running and the dash controls are on , if the pump runs you'll have to look for a leak in the vacuum system.

[STEAMBOAT99]

Skip thanks for the information I couldn’t see Evans but I do have a pump out front like you showed me when I check this I should be able to feel or hear the pump run and also check the 12 volts to the pump while engine is running to make sure their no blowed fuse. Do you have a place you recommend to buying parts like this. Thanks again I will let you know as soon as I can check it

[Skip426]

Ford diesel pick ups use a similar vacuum pump , that's available at auto parts stores , wiring connector may be a slight issue.

www.evanstempcon.com/

See the blue oval .

[STEAMBOAT99]

Skip my pump is a Ford pump that after looking at it good I found iTHE 12 volts was unplugged I am guessing by the RV shop that ran the new AC line I plugged in in and everything is A OK THANKS AGAIN. STEAMBOAT