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Topic: AC/Fan not blowing air thru instrument panel -Dorman Vacuum Tank Unit is the fix (Read 801 times) previous topic - next topic
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AC/Fan not blowing air thru instrument panel -Dorman Vacuum Tank Unit is the fix
I was just checking whether the rig would start as I'm going somewhere soon (no problem here) and noticed  that the fan is not blowing any air through the instrument panel registers into the cabin but only against the front and side windows. The selector was - as usual - on "Norm AC" (I don't think I had it ever anywhere else). Now it does not matter what I do with the selector - unless it's on "off" - or the fan speed or the temperature, the wind goes always only through the defrost openings. AC and heater as such are working normal. Three or four weeks ago, when I was using the RV the last time, everything was working normal.

I'm kind of in panic about this. Can somebody tell me what might be going on here and whether I can fix this easily myself?

Klaus
2001 26.5 Mid-Bath
Re: AC/Fan not blowing air through instrument panel
Reply #1 –
Quote from: Klaus date=1557965753 link=msg=203012 I'm kind of in panic about this. Can somebody tell me what might be going on here and whether I can fix this easily myself? [/quote
?

The vent controls are vacuum operated, vacuum supplied from the engine's intake manifold and stored in a vacuum can, hidden somewhere under the hood. It's a complicated system that is hard to access.
The vacuum supply tube, on the E450s, is located under the hood, on the left side. From there is disappears into the interior, under the dash.


Fix it yourself?
I would start by reading the HVAC section in the Factory Service Manual, which you probably don't have.
Without any information on how operates, it's going to be difficult repair unless it is something simple, like the vacuum line falling off the intake manifold. I would start with the shown vacuum line and seeing if there is vacuum present when the engine is running.  Beyond that, unless you are a talented and very patient tinkerer, I would suggest professional help.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: AC/Fan not blowing air through instrument panel
Reply #2 –
I certainly cannot tinker with this myself. I don't even know where exactly the vacuum line in the picture is. I can only guess that it's the metal/brass tube with the right angle on the right side - is that correct? Nothing seems to be loose or missing there.

PS: The piece that gets cold when the engine is running is the black metal tubing that is in the picture more at the bottom. Is that the vaccuum line?
2001 26.5 Mid-Bath
Re: AC/Fan not blowing air through instrument panel
Reply #3 –
Klaus,
I have had this same problem twice.  The first, time a rat chewed through the vacuum line.  Fortunately, it was right at the top where it is shown in Larry's photo.  Check this location and carefully work your way down that vacuum line, but don't pull it! When I found the break, I simply obtained a short section of vacuum line slightly larger in diameter and joined the two separated ends.  Viola! Problem solved.  Everything worked as designed. 

The second time, a rat or other ilk, chewed through inside the fender area and I will have a more difficult time rejoining the ends.  Hopefully yours is an easy repair!

Harold
2014 27 MB
Towd: Either the Jeep Wrangler or trailer containing the BMW R1200GS and 2 E-bicycles
Happy wife=Happy life
Re: AC/Fan not blowing air through instrument panel
Reply #4 –
We had the same problem several months ago and fixed it with the help of another LD friend, Chris. He did most of the work but I get credit for handing him tools.

Here is an older thread on the subject. Cab A/C turns off when going up hill

Something from the Companion. The Lazy Daze Companion: Cab AC - Air Flow Cuts Off Under Acceleration

When it's failing I believe it cuts off under acceleration. When it gets worse it only blows through the defrost.

Jim
Re: AC/Fan not blowing air through instrument panel
Reply #5 –
Ok. First - thanks to both of you (now: all three of you; Jim answered while I was writing this).

I'm still not really clear about the vacuum line. According to some research it is usually a flexible rubber hose - of which there are many under the hood. I will wait a little longer until the engine is cold and then feel around the rubber hoses as much as I can.

Harold, it sounds as if you have not repaired the second rat attack. Is that correct? Does that mean that for the time being it is possible - and not risking further damage - to use the RV? I am planning to drive tomorrow from Sedona to Flagstaff (30 miles away) to have finally my solar system installed. This is scheduled at "Buddy's Welding & RV" in Flagstaff. This place has been recommended to me by several people and also the people from Northern Arizona Wind & Sun where I bought most of the solar equipment.

I will, of course, ask Buddy whether he can have a look at it, but I'm not sure that he is a Ford E-450 engine and AC specialist. I will find out tomorrow.

And then next week on Wednesday or Thursday I want to go for about ten days onto a trip to Temecula, CA (via Phoenix and Quartzsite). That's back and forth about 1,000 miles. I would stay most of the time at Jojoba Hills RV Resort in Aguanga and drive from there every day to a seminar in Temecula. Having the cold air only coming out through the defrost vents is certainly not ideal, but I guess I would survive that.

Can I go ahead with my Temecula plans, or do I have to postpone until this is fixed?

Klaus
2001 26.5 Mid-Bath
Re: AC/Fan not blowing air through instrument panel
Reply #6 –
Jim - are you and Gayle right now in Aguanga? Klaus
2001 26.5 Mid-Bath
Re: AC/Fan not blowing air through instrument panel
Reply #7 –
Klaus,
Go ahead and take your trips and enjoy your Lazy Daze.  Don't  worry about it.
The default (no vacuum connection) is to blow the air, ac, or heat up along the window like a defroster. This is a good safety default and actually keeps the cab at a desired temp.
unless the break is obvious, I doubt that a general repair shop will be able to fix this. Kearny Mesa Ford in San Diego estimated it at $1100.
I can do a lot of shade tree repairs for $1100, and quite possibly so can you.
Check out YOUTUBE. There are some videos on this and you will be able to ID the vacuum line.
Good luck.
Harold
2014 27 MB
Towd: Either the Jeep Wrangler or trailer containing the BMW R1200GS and 2 E-bicycles
Happy wife=Happy life
Re: AC/Fan not blowing air through instrument panel
Reply #8 –
Klaus, if you don't get it fixed before your Temecula trip and you are comfortable with night driving, you might want to plan your driving to be after sunset when it will be cooler out.  A trick from my childhood days when air conditioners in vehicles were rare/non existent.
There are also 12v fans that can help distribute the air towards you from the vents that are blowing air.
Jane
Jane & Scott
Currently have a 1989 TK  LD we did a lot of upgrades on.
Bigfoot 25RQ Twin on order with early summer 2024 ETA

Our smartphone autocorrects into very poor English.
 We disclaim the illusion of ignorance this creates as we have enough ignorance we rightly claim.
Re: AC/Fan not blowing air through instrument panel
Reply #9 –
To answer your other question, No, I haven't  repaired the second break. It's  on my short list, but the cab climate is OK with the air blowing out of the defrost vents, so it is an easy thing to live with. Due to the location of the present break, this will be more difficult, bit I'm pretty certain I can figure this repair out. 95% perspiration and 5% inspiration...
I did get rid of the damned rats.
Harold
2014 27 MB
Towd: Either the Jeep Wrangler or trailer containing the BMW R1200GS and 2 E-bicycles
Happy wife=Happy life
Re: AC/Fan not blowing air through instrument panel
Reply #10 –
What Jim Cummings termed "Something from the Companion" is, to me, a comprehensive How-To on how to resolve the issue. It is certainly better than any YouTube I have seen on the subject.
But as Klaus said "I certainly cannot tinker with this myself", so the options are a mechanical friend or a thousand bucks for a tech.
Don & Dorothy
Sold our LD in June of 2023

Our boring always non-PC travel blog
Traveling Dorothy
Re: AC/Fan not blowing air through instrument panel
Reply #11 –
Klaus,

Don and Jim did the heavy lifting here.  The Companion article is pretty clear how to fix the problem or at least determine the cause.

 Companion. The Lazy Daze Companion: Cab AC - Air Flow Cuts Off Under Acceleration

OK.  5% inspiration is done.  It is time to get out and replace my vacuum line.

Harold
2014 27 MB
Towd: Either the Jeep Wrangler or trailer containing the BMW R1200GS and 2 E-bicycles
Happy wife=Happy life
 
Re: AC/Fan not blowing air through instrument panel
Reply #13 –
Can somebody please confirm that the vacuum in Larry's photo is the rather thin black line on top with the short yellow jacket in the middle? I probably could not sleep well tonight if I would not at least know which line we are talking about here.

Apart from that I'm one more time very happy to have a Lazy Daze. The knowledge and the support here in the forum are simply outstanding. Thanks!

Klaus
2001 26.5 Mid-Bath
Re: AC/Fan not blowing air through instrument panel
Reply #14 –
Quote from: Klaus  - 
Can somebody please confirm that the vacuum in Larry's photo is the rather thin black line on top with the short yellow jacket in the middle? I probably could not sleep well tonight if I would not at least know which line we are talking about here.

In the photo, the vacuum line is the small tube with a wrap of yellow tape,  It is located, with the hood up, in the far left, upper corner of the engine compartment.  It could have pulled free or a hungry rodent may have chewed on it . If so, it causes a vacuum leak, small enough that the computer can compensate, preventing engine damage. .
Rats cause a lot of under-hood damage, especially in RVs parked for periods of time in rural areas. Plastic tubes and coated wires are very tasty fare.
The valley, between the engine's heads, is a popular area that is often converted into a spacious rodent condo.
Rat damage | Flickr

There are a couple of possible causes here, either a broken or disconnected vacuum line or a bad check valve.
The classic test for a failed check valve is the A/C works fine, when idling, in neutral. with the  A/C changing air outlets under hard, prolonged acceleration, as encountered in an uphill climb . If so, the previous links will head you in the right direction.

If the condition exists all the time, you have either damaged lines, a damage vacuum storage can, something disconnected or a failure of some part in the dash.
It's all guessing without more testing and data.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: AC/Fan not blowing air through instrument panel
Reply #15 –
Quote from: Larry W  - 
In the photo, the vacuum line is the small tube with a wrap of yellow tape, ...
Thanks. Now I can go to bed.

I will test the AC tomorrow morning on my way to Flagstaff when I pass through a stretch of switchbacks and climb almost 1,000 feet. It will be rather cool (if not cold) when I drive through there and it's not very long,  but maybe it tells me nevertheless something new about the air flow.

Klaus
2001 26.5 Mid-Bath
Re: AC/Fan not blowing air through instrument panel
Reply #16 –
Quote from: Klaus  - 
Thanks. Now I can go to bed.
I will test the AC tomorrow morning on my way to Flagstaff when I pass through a stretch of switchbacks and climb almost 1,000 feet. It will be rather cool (if not cold) when I drive through there and it's not very long,  but maybe it tells me something new about the air flow nevertheless.

It doesn't matter if the A/C is on or not, the vacuum powers the vents in all modes.

Now, get some sleep.
Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: AC/Fan not blowing air through instrument panel
Reply #18 –
Felt I needed to confirm using the Companion.  I was able to fix the same issue with the info provided in the Companion and watching a few Youtube videos.  Once I confirmed the vacuum line was the one as noted by Larry W, I traced it through the firewall to the inside passenger foot well.  24" of vacuum line and a new "ball" vacuum reservoir and all is well.  Only issue I have had was effectively mounting the reservoir behind the metal plate behind the passenger knee bolster. Velcro did the trick.
Art & Bonny Taylor
Lazy Daze Newbs
2001 Green 30'TB "Maeve"
Re: AC/Fan not blowing air through instrument panel
Reply #19 –
And here is one more:

My 2014 chassis has the vacuum tube routed differently than the example in The Companion.  However, the principle was the same.  $3.50 for a few feet of 5/32" vacuum tubing from my local NAPA store and my dash vents now blow the air from the vent, heater and AC. The dash climate control selector knob works now as designed.

Although I didn't need to replace the check valve or the vacuum accumulator, the $1100 quoted by the Ford dealership seemed a bit excessive.

Thanks to Don and all of the contributors to the Companion.  It is a really valuable resource.

TPMS is next.

Harold
2014 27 MB
Towd: Either the Jeep Wrangler or trailer containing the BMW R1200GS and 2 E-bicycles
Happy wife=Happy life
Re: AC/Fan not blowing air through instrument panel
Reply #20 –
I started with the (hopefully sucessful) repair of the vacuum line in my Lazy Daze. I looked at a couple of YouTube videos - some good, some not so good - and also the lengthy article on the Lazy Daze Companion website. For a while a thought I would not be able to do this myself, but then I just started.

At first I wanted to follow the instructions from a pretty good YouTube video (link at the end of this post). For that I removed the doghouse, which was after having done it before for replacing the radio not so difficult anymore, and found a deserted critter nest in the small valley in front of the transmission (see Critter Nest.jpg). I cleaned that out and put some mothballs there instead to discourage critters to try to live there again.

In-between question: Could the mothballs cause problems due to heat from the engine? (I anyway have mothballs in the engine compartment, on the driver side in the front below the electrical box. These do not cause problems, but they are also not getting hot.)

With the doghouse off and looking again at the YouTube video I changed my mind and followed the Lazy Daze Companion instructions. As it turned out that was a good idea because when I removed the grommet that holds the vacuum line that goes from the passenger side through the firewall into the engine compartment I immediately had the line in my hand because it was broken (or bitten through) right behind the firewall (Cut Vacuum Line.jpg). I probably would not have found this if I had followed the instructions from the YouTube video. Lucky me! I then fed a copper wire from the passenger compartment into the engine compartment and was able to fish this up next to the battery (Copper Line.jpg).

I got already the new vacuum line and the vacuum canister is arriving today. Putting this now together as described on the Lazy Daze Companion website should not be very difficult, I hope. And I further hope that the AC then will work again as it should!

Klaus

YouTube video: https://www.youtube.com/watch?v=83GY1da-WOQ
2001 26.5 Mid-Bath
Re: AC/Fan not blowing air through instrument panel
Reply #21 –
Good job.  Finding the problem is often 3/4 of the battle.

I hate rodents.  All of them.
2014 27 MB
Towd: Either the Jeep Wrangler or trailer containing the BMW R1200GS and 2 E-bicycles
Happy wife=Happy life
Re: AC/Fan not blowing air through instrument panel
Reply #22 –
“I hate rodents”

Me too, Harold. Just got this bugger this morning. Eight so far this season.
Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264
Re: AC/Fan not blowing air through instrument panel
Reply #23 –
Could the mothballs cause problems due to heat from the engine? (I anyway have mothballs in the engine compartment, on the driver side in the front below the electrical box. These do not cause problems, but they are also not getting hot.)

A direct answer is yes

To read more info ----  Health Effects of Mothballs

glen
personal fine art photo stuff
TF Mack | Flickr
It's all good .......
2014 Twin King
Re: AC/Fan not blowing air through instrument panel
Reply #24 –
I got the Dorman vacuum canister and have - to be sure - more questions as I am slightly confused by the Lazy Daze Companion instructions in regards to which line to connect to which nozzle on the new vacuum canister.

1.) It is possible to blow into the smaller nozzle of the Dorman vacuum canister and then the air comes out of the larger nozzle, but it is not possible to blow into the larger nozzle. I therefore think that the smaller nozzle (in the picture on the right side) is the inlet and the larger nozzle (on the left side) is the outlet. Correct?

2.) The inlet should be connected to the newly bought line that goes (in the engine compartment) to the intake manifold, and the outlet should be connected to the existing line (in the passenger compartment) that goes up into the dashboard. Correct?

Or should it be the other way around?

3.) Once that is settled and the new line is running from the passenger compartment to the engine compartment I simply cut the old vacuum line in the engine compartment somewhere on the left side of the connector that connects is to the line that goes to the intake manifold and connect this old vacuum line to new line (which is connected to the intake nozzle of the new vacuum canister). Correct?

Klaus
2001 26.5 Mid-Bath