1996 Winnebago Adventurer dash Air Conditioner blowing warm through defrost. Need hel

[Reeksweets53]

Hello everybody,

New to the site but I'll get right to it. I have a class A Winnebago Adventurer 34ft gas RV that I've owned 3 years. From day 1 of me owning it the dash air has blown warm through the front window defrost only regardless of what control settings I choose (max air, vents, normal air). I opened the hood and doghouse inside to poke around checking vacuum hoses and found 1 of them as brittle as toast. Went to Autozone and easily replaced the hose, HOWEVER... I did notice a very thin RED hose coming from the top of the engine vacuum area on the passenger side just hanging down with a weird fitting at the end (the fitting looks like the end is broken off). I left the RED thin hose alone although I could clearly hear hissing when running the engine coming from the broken end that was just dangling down. Next I attempted to add refrigerate with a gauge attached to the refrigerate can to monitor levels (Autozone) with engine running and control set to at max ac setting. The pressure line chilled as expected while refrigerate was being pumped in, the ac inside did not cool nor did the compressor kick on and off. The air inside still blew out of the defrost window vent and little out of the front dash vents. I noticed another *larger aluminum pressure line port (not attached to the hose located in front of the small radiator condenser was hissing out what I suspect was the little refrigerate I was trying to charge the system. So although I replaced I black vacuum hose, I still do not know where the really thin RED hose with the broken off tip fitting goes, still only have defrost node regardless of what i select on controls, still blowing warm air, and lastly losing refrigerate out of a port off aluminum line. Please help, I'm fairly handy and follow directions well.
Thanks in advance!
From Cincinnati, Ohio

[Jim_HiTek]

Since this is a gas engine, it creates a vacuum so look for the other end of that broken red hose on the engine. Probably semi-rigid plastic. Check around the engine for where it might have connected OR for the end of another hose.

I'm more familiar with diesels and they have a small vacuum pump to handle the dash comfort controls. But the '94 Bounder I owned had a large vacuum motor way back near the engine. But it also provided vacuum to the Cruise Control and the dash comfort control.

They still use vacuum for the dash comfort controls because it just works better and is more reliable then other systems.

Your symptom of only blowing air through the defrost vents is the tip off that you are missing vacuum. The air systems are designed to default to defrost if you lose vacuum so it's doing it's job. The red hose is bound to be the primary vacuum feed to the control, and if it's disconnected, no vacuum, so 'defrost'. Since you say it's hissing (it should be sucking)...that means that the engine side is connected and you're looking for a vacuum switch of some kind.

Maybe take some pics of the engine compartment where that red hose is and post them here.

Get that fixed first, then we'll talk about the dash AC.

[Morich]

Agree with the above thinking, but I might look up under the dash if that tube would reach that far. The controls tend to break off and that hose may go there????
A big point to keep in mind is that things like this are often mostly considered part of the chassis, so looking for info on whatever chassis your Rv is setting on is the better place to look fo info than looking at RV info.
Not meaning to put you off on asking here but the better info on the running portion will often be in books on that end of things.
I might go this way. Find what chassis you have, go to online, library or parts stores for info n that chassis and hope to find a good drawing of the vacuum lines. The older they get, the less info may be found but 96 is not that old, just well broken in!

I thought I was getting old but then I had to correct the guy giving the cognitive test!

[Wyatt]

Originally Posted by Morich

I thought I was getting old but then I had to correct the guy giving the cognitive test!

I loved this part of your answer...

[Morich]

Originally Posted by Wyatt

I loved this part of your answer...

He was going to give me three words to remember, apple, table and knife, but I could not figure what he was saying when he repeated it as APEPUL, until I told him I just did not know what apepul meant. He was embarrassed and admitted English was not his first language but he did say I passed!
I was a little worried that he was going to do something hard like have me make a sentence but all he wanted was me to be able to tell him the three words later.
Then we got into the hard stuff, like point at the wall and which door I came in!!! Tough stuff when in a 6X6 exam room!

[Bones2003]

ReekSweets53, go to this website https://proairllc.com/design-enginee...empcon-guides/ They have a ton of troubleshooting information that will be very helpful. They may not have your exact system described but all those gas units from the time were pretty similar. The red vacuum hose is exactly the hose that controls whether the air comes out on the floor, the dash vents, or the defroster vents.

[NeilV]

The thin plastic vacuum lines are notorious for turning to dust over time and are many times used for very long runs from under the dash to the unit under the front hood and possible to the vacuum reservoirs behind the front bumper/fairings.

When they start failing they can develop pin hole leaks along their entire length. And yes indeed it can sometime be a chore to follow them all to their final connections. You can usually splice them using short lengths of 1/8 or 3/32 inch rubber tubing

When there is not sufficient vacuum for correct operation the fail-safe mode is to have warm air blowing out the defroster vents.

[Geosman]

While you are there under the hood do some more checking around. With our first RV during a winter storage season it seems some squirrels took up residency on my engine block. Their taste for adventure ate through the foam gasket between AC coils and the dash, chewed up my vacuum lines and power wiring to the gas injectors....Talk about a nightmare. Did not discover until we left for a summer trip. had to use the generator and roof AC for cooling on the road but it sure got warm up front. From that time on it was winterized with a box of D-con setting on the battery.

[Geosman]

As for your AC; there may be some comments from others but in my experience I find the oil used with systems using Refrigerant 134a will absorb moisture if left open to the atmosphere.. If your system is losing refrigerant as you fill it, its likely been open for as long as you've owned it or before? There is a filter drier in the system that will need to be replaced once any leaks are located and repaired. I might suggest doing a pressure test to locate all leaks before any major repair attempts. Once the system is again tight, run a vacuum test to at least 500 microns if at all possible. If this is good it's time to replace the filter drier and while the system is open make certain the old oil is blown out before adding new oil and placing it back on a vacuum pump. If it can hold vacuum its good to go ahead and charge with new 134a refrigerant. The compressor will not engage unless the refrigerant pressure is likely up in the 30 to 40 psi range on the suction side of the compressor which corresponds to a coil evaporating temperature in the 25-35 degree range ie a nice cold accumulator on the suction side of the AC compressor. It is the low pressure switch that will cycle the compressor off if the pressure drops too low either because the coil may start to freeze up or because the system has lost adequate refrigerant for safe operation. Data for oil and refrigerant charge for your compressor should be available via most auto parts stores once you are able to identify its make and compressor model.
Good luck Tools can be expensive WW Grainger, NAPA and Auto supplies plus Harbor Freight might be your likely sources.