2002 Adventurer 35U Dash Air

[JoePit708]

Not sure if these issues are par for the course so I figured why not find out. System seems to hold a charge so no issues there. We live in AZ so on really hot days I run the generator and basement AC.

The dash AC only will get somewhat cold when I'm at highway speed. Come to a light or let it idle and it seems to shut off completely. Little humid today so you could easily tell by the condensation dripping when you stop but that will stop fairly quickly and the air will blow hot. I noticed there is a valve under the hood. Is that for the heat system when it is cold and should I shut that off. Usually do this on older semis not sure if the same thing is going on here.

Also the outside temp was about 87 when I was fiddling with this earlier and even while driving on the freeway it blows out about 73 degrees at most.

Any help with this would be appreciated.

[Jim_HiTek]

With a diesel rig, there are always two water shut off valves for the dash heater near the engine that owners usually shut off when summer rolls around. They, DIY'ers, also put them under the hood since it's easier to get to.

On a gas engine, I think usually you'd find them only if one of the owners installed it and if you have a valve in the heater core hose, yea, shut it off, see what happens. I won't hurt anything. Remember in the olden days when your heater core would leak? You'd pull both hoses and connect them together under the hood? Many RV'ers do the same thing, or a similar thing, like add shut off valves.

[creativepart]

Originally Posted by JoePit708

The dash AC only will get somewhat cold when I'm at highway speed. Come to a light or let it idle and it seems to shut off completely.

Your explanation could be a number of things. The most obvious is low "freon" but also the compressor clutch might be an issue and who knows what else.

The best place to go for a complete diagnosis is a car or truck A/C shop.

[BobC]

Originally Posted by creativepart

Your explanation could be a number of things. The most obvious is low "freon" but also the compressor clutch might be an issue and who knows what else.

The best place to go for a complete diagnosis is a car or truck A/C shop.

I agree. Basement A/C Issues = DIY, Dash Air Issues = Truck A/C Shop*

*Assuming it's truly a cooling issue and not an air flow or drive belt issue. In my younger, and poorer, days I may have tackled a clutch replacement, but not now. Some clutches are an integral part of the compressor and can't be replaced without replacing the whole compressor.

I recently had a problem with my E350 van's A/C, took it to the shop, they checked it over, replaced a leaky line, recharged it. Everything was fine until it failed again after sitting for a week. I took it back in and they found another line with a pinhole leak. There's no way I could have diagnosed and fixed all this. Fortunately, the re-work was free.

[Fletcher0077]

I have the 8.1 workhorse. Motor is great but GM AC system is poor quality. My compressor started leaking at 25K miles. I added freon every spring for 4 years then finally had AC rebuilt for $1200.
Part of the cooling problem is the fan must pull air thru the AC, trans cooler and radiator. When going slow there is no ram air effect to aid fan, at 60 MPH it cools pretty good.
I did 2 things to help this. 1. I installed a manual valve to make sure hot water was not running thru the heater core.
2. I improved the seal between the fan shroud and the radiator. OE has strips of rubber which clip on the shroud about 1.5" wide. I found one under the MH then discovered the poor design. I cut medium duty 1/8 " plastic strips 4" wide and taped the to the side of the radiator and shroud. They are about 18 to 24" long. I cleaned the surfaces and used aluminum tape to tape it in place. This keeps air being pulled thru radiator and not coming in behind the radiator. I may replace that with Eterna bond tape since it's working so well.
What an improvement! I can drive thru town with stop lights and stay cool. On the Highway on 95*+ days I don't need high unless the sun is coming in the windshield. No gen/AC needed.

[cef2lion]

Make sure your vacuum lines to the AC system are not leaking. Just went through this on my 2004 35U. The main vacuum line from the engine to the vacuum reserve came apart due to age and heat under the dog house. Then I found the AC vacuum harness had leaks. Replaced the entire harness. The hot water shutoff vale was not closing. Also, the flap that recirculates cabin air instead of drawing air from outside was not closing. On mine the hot water valve and that air flap only close in MAX AC mode. And, if you have a vacuum leak the system will default to the defrost ducts.

[catmandoo62]

i just went thru this myself.20 years and those plastic hoses are junk.

[BobC]

I haven't noticed any problems with my 2002 35U's dash air but I've not only subscribed but bookmarked this and cef2lion's thread for future reference.

Thanks.