New class a dash ac only moderate cooling

A Class A motor home is built up on what is basically a TRUCK chassis, Think about the cab of say a Ford F-350 or such.. now that is how much the A/C is designed to cool.

That should explain it.

I see mine coming out (measured just behind the outlet) at below 40 and I'm still hot, and I calibrated the thermometer too so I know it's right.

On any given day I would test the MH vent temps, then test your car vent temps using the same thermometer the same way. They should be similar. When my system leaked R-134 at the trinary switch it was running only slightly cooler than outside temps. After changing the switch and adding a several cans of R-134 I was reading 45 degrees on a 80 degree day measured at the vent with an IR gun. Your MH is brand new I would take it back to the dealer after you run the test and have them fix it. Also look for leaks at the fittings and switch the leak will be oily and yellowish green. Hope you get this resolved.

I think you should expect the Dealer to demonstrate how they did the test that netted 52*

A friend's older Class A (little 25-ft on Workhorse with Evans A/C) didn't cool very well and I found that it was taking in way too much outside air. Setting to MAX closed the outside air intake and it cooled much better.

So I took it back to the RV place and they tested it and said it's 52 degrees coming out.. and working fine.

I'm just trying to figure out how they tested it. From the vents it is NOT 52 degrees. It's hot down here now and it's not even cool. I can turn it to vent and it feels exactly the same as MAX AC..

but the rv place is telling me it's fine.


Is there some way to test it w/out actually using the vents? Maybe they tested the lines, but the max AC nob is not opening the valve correctly?

Anything y'all can suggest? I never actually sat in the unit with the repair man to see what he had to say about it so i'm doubting the whole thing.

For anyone's information; I get 49 degrees out of the dash on our Freightliner. As was already mentioned here; it is a good idea to help the AC out by closing the valves (if equipped) in the heater hoses, near the engine.

Well I called Winnebago. Jake was not very helpful heh. He said call the dealer and they should be able to fix me up..

I called my dealer he's going to call me back. They have a satellite shop in my city hopefully they handle it for me so I don't have to drive the 45 mins to their service center with it.

I know Winnie's online documentation is outstanding. I also know a neighbor used to get troubleshooting tips about his Itasca DP over the phone. I have a Jayco so I haven't tested Winnie's Help Desk.
But I'd say call Winnebago. If you said "do they leave a connector off?" or something like that they just might give you a tip that keeps you from having to go anywhere.

thanks, J-d. Hopefully it is a simple issue. Should I call Winnebago or just my dealer?

I see your update! Starting to sound like a Control Problem. Perhaps a Vacuum line damaged or disconnected. My guess would be a connection wasn't made up and the issue wasn't found on the PDI. Probably looked at Coach systems and not Chassis systems.

The "dash air" in older Class A gas coaches was really a mess. I say "gas" because I know about them, and not much about diesel pushers. Both share the issue that the chassis supplier send a bare chassis and the coach builder adds the Dash Air among many other things. Years ago, the Class A Dash Air was cobbed together out of whatever the builder could find, could get a price on, or their suppliers could provide on demand. No quality control, very likely not even a knowlege of what the parts were for repair time.
I THINK it's gotten better. A/C provided by chassis supplier, or at least a motorhome unit bought as a unit by the builder. I also have a lot of confidence in Winnebago as being one of the better builders.
This could be as little as a wire off, connector unplugged, etc.
A "static" pressure test tells you very little about whether you have adequate refrigerant in the system. It's the nature of refrigerant to expand to a certain pressure at a certain temperature regardless of quantity in the system. Say it calls for 36 ounces of R134A. From a Chart, R134A at 85*F will show a static (system not running) pressure of 95.3 PSI. It will show that 95 PSI full at 36 ounces or nearly empty at 6 ounces. But turn it on and it sure won't cool at 6 ounces! In fact, if it's that low a low pressure cutoff switch won't allow the compressor to even run. So YES it could have leaked down.
If your dealer's good, they'll find it and fix it. If they're good and can't they'll arrange it to go to somebody who can.
On the other hand, a good shade tree mechanic might just find there's a wire off.
But it needs to be looked at. And I'll wager you'll get the cold air you want when it's corrected. I drove a used 30-ft Winnie Sightseer in FL on a hot day and it cooled fine.