Chinook RV

I recall reading about this issue somewhere, but not sure where. When going up hill my a/c seems to divert to defrost and then comes back to normal vents after the climb is done. Vacuum leak somewhere? Thoughts on how to find it if so?

Not suggesting its safe by any means, but in my younger intellectual days we would spray ether at the suspecting gasket or vacuum hose, if the engine rpm increased we knew there was a leak.

Yes that's a classic vacuum leak sign. Many things run with vacuum and the default mode when there is not enough is for the dash HVAC to default to defrost position only.

If you just have a leak in a line (one place you can look is under that false, sort of kidney shaped panel on the dash over toward the passenger side - quite a few vacuum lines in there) then you can "just" fix it.

But another reasonably common problem is for the main vacuum canister or check valve to go bad. In order to fix this the official way, you have to remove the entire dashboard, Air-con, and some other stuff. Upshot is it's like a 15 hour Ford job and who knows how many other things will be disturbed in the process. An alternative is to cut a hole in the passenger fenderwell from underneath. As you can see, none of these options is appealing in the least. But there is another way! This has been well documented on the Ford Truck forum (they have a van sub-forum) and some legit shops do it as well. What is done is to buy an aftermarket vacuum canister and check valve (or the stock Ford one I suppose if you want to), and then locate it in a new place (usually up under the passenger footwell dash area) and connect the stock vacuum lines to it, thus bypassing the completely buried and dysfunctional stock one. I'd recommend reading about it on the Ford Truck forum van section, as it has been well written up there. Some shops understand and do this as well if you do not want to DIY.

Of course it may not be the canister/check-valve, but just mentioning it as it does happen.

Here is a good read on the vacuum problem related to Ford E series.
http://www.ford-trucks.com/forums/10771 ... sters.html

Blue~Go wrote:But another reasonably common problem is for the main vacuum canister or check valve to go bad. In order to fix this the official way, you have to remove the entire dashboard, Air-con, and some other stuff. Upshot is it's like a 15 hour Ford job and who knows how many other things will be disturbed in the process. An alternative is to cut a hole in the passenger fenderwell from underneath. As you can see, none of these options is appealing in the least. But there is another way! This has been well documented on the Ford Truck forum (they have a van sub-forum) and some legit shops do it as well. What is done is to buy an aftermarket vacuum canister and check valve (or the stock Ford one I suppose if you want to), and then locate it in a new place (usually up under the passenger footwell dash area) and connect the stock vacuum lines to it, thus bypassing the completely buried and dysfunctional stock one.

That's what my Ford dealer did to fix my issue. Been working great.

Skillet wrote: That's what my Ford dealer did to fix my issue. Been working great.

Presuming you mean the "alternative" fix, it's good to know that a Ford dealer will do that as well (vs. the 15 hour one).

Yup sorry, the alternative fix. He explained the 15hr one and said he really wanted to save my pocketbook from getting destroyed!