Hello...I have a 2001 Ford V10 E450 running my class C and just this weekend we were driving and notice the fan for AC or Heat or vent will go from dash air to defrost when the motor is under stress like going up hill. If I let off the gas the air flow switches back to coming out the dash vents from defrost. I was looking around the internet and some have said this can be a Vacuum check valve located somewhere over the driver wheel well. Anyone have this problem before? How much is part?? How do you fix it?? Someone on the internet said you have to remove a ton of stuff to get to it and there are other methods of dealing with this problem. Motor runs fine no misses or anything just this issue. Thanks

Hi,My older class C had a small vacuum canister, it was about the size of a large softball, about 4" diameter. There must have been a check valve between the intake manifold and this canister, and then the vacuum controls on the A/C system. I never had a problem with the A/C changing to defrost while driving. If you can find the vacuum line going to the A/C controls, you already know that there is a check valve between the controls and engine (it might not be working though) you can install a vacuum canister in a tee to that line. You might also need to install a new check valve. You do not require to dfind hte factory one, just put it inline with the vacuum hose going towards the dash air controls. Napa should have a vacuum canister. Basically if you can fit it under the hood, it will work. You can even mount it remotely, and mount it under the RV (especially if it is metal) then run a 1/4" vacuum line to it. Good luck finding everything. Fred.

Its likely more than a bad check valve. You probably had one of the lines eaten by a critter.

Is there a set of plans for this system? I have been looking around..I'm going to have to try and do this myself being that the dealer will want a ton for this.

I had the same problem with my 2005 E450. Their is a RED plastic vacuum tube under the hood on the passenger side near the oil fill & the windshield washer fill. I installed a checkvalve($5.00 at Auotzone)between the red plastic tube and the black rubber hose it goes in to. Use a small zip tie to secure the checkvalve to the rubber hose. Worked for me.

Ok Ken did it today just need to try it out on a hill. Will let you know otherwise its off to the dreaded dealer. Thanks

2001 E450 SD Vacuum check valve?? | Good Sam Community

carringb
Explorer
Sep 16, 2013
Its likely more than a bad check valve. You probably had one of the lines eaten by a critter.
Golden_HVAC
Explorer
Sep 16, 2013
Hi,

My older class C had a small vacuum canister, it was about the size of a large softball, about 4" diameter. There must have been a check valve between the intake manifold and this canister, and then the vacuum controls on the A/C system. I never had a problem with the A/C changing to defrost while driving.

If you can find the vacuum line going to the A/C controls, you already know that there is a check valve between the controls and engine (it might not be working though) you can install a vacuum canister in a tee to that line. You might also need to install a new check valve. You do not require to dfind hte factory one, just put it inline with the vacuum hose going towards the dash air controls.

Napa should have a vacuum canister. Basically if you can fit it under the hood, it will work. You can even mount it remotely, and mount it under the RV (especially if it is metal) then run a 1/4" vacuum line to it.

Good luck finding everything.

Fred.

Forum Discussion

2001 E450 SD Vacuum check valve??

About Motorhome Group

Related Content

check valves

water pump check valve

Check valve

Check valve replacement

Best vacuum