Cab AC air flow cuts off under acceleration - The Fix

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Cab AC air flow cuts off under acceleration - The Fix

August 09, 2017, 01:44:43 pm

Our cab AC air flow cuts off under acceleration or when hill climbing. This is common in all E-series Fords.
The air flow does not really cut off, it goes to the default setting, the defrost vents.
I have known the cause, but my limited skill set has prevented doing a DIY fix.
Ford will be pleased to fix it for $800 or so.
The cause is a leaking vacuum hose or the check valve has gone south.
[Larry Wade concurs if you need validation of the cause of the problem]
I am too cheap to spend $800 on labor to replace $20 worth of parts.

This morning I had a brilliant idea - Google for 'replace vacuum check on e450'
About 168,000 results, including Youtube How-To's, post on other RV forums.

Now all I have to do is fully understand the procedure before I cut the vacuum line.

Should I have success, I will post pictures on The Companion.

Re: Cab AC air flow cuts off under acceleration - The Fix

Reply #1 – August 09, 2017, 02:11:08 pm

Don the link attached from a few weeks ago discusses this. Take a look at the sportsmobile link from the thread in particular.

Air flow problem, vacuum leak?

Jim

Re: Cab AC air flow cuts off under acceleration - The Fix

Reply #2 – August 10, 2017, 09:25:00 am

Yeah, I recall the recent post, but I could not locate it to add what I thought was new information. Now, I see it was covered two years ago but was not captured for The Companion.

My unsaid reason for posting is that I should always search the web for things like this before posting here. There are a lot of E-series out there with the same problem.

Re: Cab AC air flow cuts off under acceleration - The Fix

Reply #3 – October 21, 2017, 04:05:07 pm

Finally met up with our friend Chris and employed the fix described in this link using the Dorman vacuum canister. It works perfectly now. Parts were around $27 for the canister and some new hose. We used superlock to attach the new canister under the dash to a flat metal plate on the passenger side.

Dorman Vacuum Reservoir 47076 - Read Reviews on Dorman #47076

Climate control vacuum leak testing? - Sportsmobile Forum

Jim

Re: Cab AC air flow cuts off under acceleration - The Fix

Reply #4 – October 24, 2017, 06:18:45 pm

Don,
Here are two pictures of the vacuum line that was cut and resulted in the cab climate control dial no longer operating and defaulting to defrost. As I mentioned earlier, I found one end loose and visible and the other end dangling near the stbd side fender. Since the two hoses were the same type and diameter, I connected them with a slightly larger piece of vacuum line and the cab climate control dial resumed working correctly.

The pencil shows the piece of vacuum line that I cobbled the two together with. I hope this is of some help.

HD

Re: Cab AC air flow cuts off under acceleration - The Fix

Reply #5 – October 25, 2017, 07:36:08 am

I know where the line is on the firewall. It's the line in the cab that I do not know how to access.

There is a way to do it so all vents respond to the dash setting and another where only the dash vents work.

Re: Cab AC air flow cuts off under acceleration - The Fix

Reply #6 – October 26, 2017, 03:07:59 am

Don said, "It's the line in the cab that I do not know how to access."

The guy at Merle Kellly Ford in Chanute, KS, found an access point in the middle of the top if the dash on mine, under the carpeted dash cover (which I'd never removed for cleaning). He showed me how hr popped it open with a straight screwdriver & reconnected the vacuum hoses.

Lynne

Re: Cab AC air flow cuts off under acceleration - The Fix

Reply #7 – October 26, 2017, 11:42:45 am

Quote from: Don Malpas - October 25, 2017, 07:36:08 am

I know where the line is on the firewall. It's the line in the cab that I do not know how to access.

There is a way to do it so all vents respond to the dash setting and another where only the dash vents work.

You have to remove the kick panel on the passenger side footwell to see the line coming through the footwell. It's the line in the sportsmobile link photo that has a transparent gromment protecting the line.

Jim

Re: Cab AC air flow cuts off under acceleration - The Fix

Reply #8 – October 26, 2017, 11:47:22 am

Quote from: Lynne Broyles-Greenwood - October 26, 2017, 03:07:59 am

Don said, "It's the line in the cab that I do not know how to access."

The guy at Merle Kellly Ford in Chanute, KS, found an access point in the middle of the top if the dash on mine, under the carpeted dash cover (which I'd never removed for cleaning). He showed me how hr popped it open with a straight screwdriver & reconnected the vacuum hoses.

Lynne

Lynne, that is something that should be checked to be sure it isn't the problem. However, everything was connected there on ours. We were never able to see a break or any chewed area under the hood but you can't see much of the hoses due to how tightly everything is packed. We assumed that the check valve in the vacuum canister was failing or since the line they used is a more rigid plastic that it had some small crack. Luckily the bypass fix worked for us.

Jim

Re: Cab AC air flow cuts off under acceleration - The Fix

Reply #9 – December 11, 2017, 01:16:39 pm

OK, Finally, I got an article on this post on The Companion

Thanks to the many who tried to help on this. Chris Ford was the person that after several back-and-forths put it in terms I could understand.

If I was a mod here I would remove all the extraneous posts to this topic.

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