Dunno, I haven't had to do it....YET


Unlike some, I admit I don't know it all....But what I do know, I know well.

 

So I was able to use Auric's post/pictures/parts list to bypass the check valve and build a new reservoir tank and the A/C is functioning GLORIOUSLY now without the air getting blown through the defrost ports on uphill climbs. I didn't check the before fix temp of the air coming out of the vents, but it seems to be colder after the fix (even when air was coming out of the normal front vents. This is awesome. Took a bit of time to get it all prettied up, but was pretty straightforward ultimately. Now I need to do the same on my dad's 2005 van that is having the same issue.

The only other issue I noticed as we were testing the fix is that if I switched from A/C or Max A/C to one of the other positions (let's say floor) and then back again, the air would return to the front vents for A/C no problem, but the air going to the back passenger vents would not return while accelerating. If I let go of the gas pedal so the RPMs went down, then the A/C would get to the back of the van and would stay that way afterwards no matter if I accelerated through right after letting go of the gas. Seems like there might be another vacuum/check valve issue maybe. Anyone familiar with this issue? At least if I let go of the gas I get the air in the back functioning again, but was wondering if there was something I need to track down or if this is normal behavior for the rear vents.

 

You may have a small leak somewhere or you may just need a larger vacuum accumulator.

 

Thanks fort he reply. When you say accumulator, do you mean the reservoir tank that is in the front (that I replaced with my bypass for the check vavle)?

 

I didn't add a large canister, I used one from a 70's Mustang and still have the drop, could my valve be bad, I put the valve in the doghouse on the red line before coming inside.

 

Yes,

I used a canister I bought for a BMW 335i but wasn't the right one for it. It was a little bit larger that a can of soda and it worked on my 2000 E150 with rear air. . the check valve should be on the suction side of the canister. The check valves are around $10.

 

Y)eah. it goes on the vac line going to the can, I wasn't sure it'd work being so small, obviously gonna need a better one.

 

I found the picture. This is the vacuum tank and check valve I used.

 

Can you get to the reservoir by removing the fender?

 

See post #74. Mine is still working today.

 

Yup, that's my "Plan B" if I can't get to the original fairly easily. I just hadn't seen where anyone had tried removing the fender to get to the canister. I don't think (?) fender removal is that difficult.

 

If it were that easy, Ford would have done that in the past as opposed to removing the system completely from under the dash to access it from inside.

 

Fender removal is very easy. It doesn't give you access to the canister. If you remove the plastic fender liner you will see that there is another "wall". Pictures on post#7 should give you an idea. I did that on my old van to replace the check valve have to do the new reservoir in less than a year. Bypass the old canister and put a new one with a new check valve on the foot well or under the van.

 

There are multiple posts from folks on this site and other forums that expalin removing the plastic liner and actually cutting a 3 sided notch in the fender all to fold the piece back to phsically access, test and replace the factory reservoir and/or vacuum valve. Then they fold it back and seal it with marine epoxy based sealant and put the liner back. I went with the bypass method described in this post and it is totally functional and much more inexpensive with home depot/lowes and auto store parts than the original tank. Only had to drill one hole in the firewall cowel for the engine and now everything is easily accessible for the future if Ihave to replace the vacuum switch again. Glorious AC is functional now even on a grade as it should be. Expeditions and and pick up trucks have easily accessible reservois and vacuum switches. Either method will work, but I was hesitant to cut holes in the fender walls. Good luck

 

Follow up: I finally had time to tackle this over the holidays... I took a lot of the existing methods and feedback and put different pieces together. IMHO this was the easiest way to approach the fix:

• Attach vacuum canister to steel crush zone under passenger dash. Canister fits up into steel corrugation with ports mounted to the top.
  Amazon vacuum canister
  Amazon vacuum canister
  (Note: this canister is not ideal, it's actually a little bigger than optimum to fit up into the crush zone. A canister more oval shaped as pictured earlier in the thread by GreeVan might fit up under the dash better)
• Disconnect red vacuum line at firewall connection near the battery, and reroute to under dash. I drilled a hole next to the dash support bracket and used a rubber grommet (but some just remove a bolt and feed through the bolt hole). I removed the rubber fitting at the end of the vacuum line to feed through the hole then reattached. Then I used the existing fitting to the vacuum port on the new canister.
• I pulled the black vacuum line at the bottom right corner of the evaporator box (under the passenger dash/footwell) as there is a vacuum line junction here. I pulled the vacuum line from the junction and then pushed the junction back into the grommet to seal up the hole as it was. Then I attached a right angle vacuum line fitting to the vacuum hose and attached to the new vacuum canister.

After reassembling everything, it works like a champ. I think this is the simplest/easiest way to fix this common problem, so hope it helps someone else needing to make this repair. It also does not cut or change any of the existing configuration or lines, so could be reverted back to original if ever needed (other than the hole drilled in the firewall).