RV Trip Planning Discussions

Go Back   iRV2 Forums > THE OWNER'S CORNER FORUMS > Alpine Coach Owner's Forum
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
 
Thread Tools Search this Thread Display Modes
 
Old 05-22-2020, 06:31 PM   #1
3x5
Senior Member
 
Join Date: Aug 2017
Posts: 132
Dash Heater/Air Conditioner Vents are Stuck on Defrost Mode.

Dash Heater/Air Conditioner Vents are Stuck on Defrost.


We have a 2005 Alpine Coach 36 FDDS. A few weeks ago, the dash heater/air conditioner vents became stuck in defrost mode. I can turn the dial to the other vents on the floor or at the waist, but most of the air still comes out at the windshield.

I took the panels off and got in behind it. The control dial has several wires of different colors coming out of the back of it. I traced them all to the heater. There are a red and a yellow wire that go to a diaphragm type of thing. There is a little arm in the middle of it that is spring loaded so it stays out, ie into the heater. With the heater running, when I pull back on the arm, the air diverts back to the floor and waist vents, and away from the windshield. But it is spring loaded, so I won't stay that way.


There are no numbers or anything on the diaphragm. The yellow and red wires are not electrical. They are hollow, so they seemed to me designed to make air pressure or suction to control the diaphragm.


Any ideas on how to fix this?
__________________

__________________
2005 Alpine Coach 36 FDDS
with Cummins ISL 8.9L 400hp
3x5 is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 05-22-2020, 06:46 PM   #2
Senior Member
 
Skip426's Avatar


 
Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 19,141
From your description , your dash HVAC unit is an Evans unit and has a vacuum pump to control dash function .
Defrost is default , no vacuum the unit defaults to defrost settings.
On the out side of the firewall , behind the grill , look for a 12 volt vacuum pump as in the picture below and check that it runs with the key on and all the hoses are hooked up to supply the dash control head.
Look for the name Evans on any of the dash units .
Attached Thumbnails
Click image for larger version

Name:	IMG_0507 (2).JPG
Views:	5
Size:	133.1 KB
ID:	286526   Click image for larger version

Name:	IMG_0651.jpg
Views:	6
Size:	328.0 KB
ID:	286527  

__________________

__________________
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Skip426 is offline   Reply With Quote
Old 05-22-2020, 06:50 PM   #3
Member
 
Join Date: Jul 2019
Location: Palatka, FL
Posts: 45
The "non-electrical wires" are vacuum lines, the lines go to vacuum operated blend door actuators. Your coach doesn't have manifold vacuum ports but utilizes a 12 volt vacuum pump usually located under front access. Either the pump has gone bad, you have a vacuum leak (line or actuator diaphram) or possibly just the fuse for the pump is blown. Hope this helps.
__________________
01 Newmar Dutch Star 4095 ISC 8.3, 350hp. 2009 Honda CR-V,
Falcon All Terrain, Me, Momma and one crazy Mini Schnauzer.
Falconeer189 is offline   Reply With Quote
Old 05-22-2020, 07:15 PM   #4
3x5
Senior Member
 
Join Date: Aug 2017
Posts: 132
Thanks.

I haven't found an air pump yet. Nothing there like the pump in the picture.

Whoever made this unit must not have been very proud of it. I haven't found a name stamped on it. I did find a tiny sticker on it on the outside of the firewall. It says "ACME." Isn't that the brand of all of the stuff that the Coyote was using to chase the Roadrunner?
__________________
2005 Alpine Coach 36 FDDS
with Cummins ISL 8.9L 400hp
3x5 is offline   Reply With Quote
Old 05-22-2020, 07:39 PM   #5
Senior Member
 
Skip426's Avatar


 
Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 19,141
" Ok with knowing the ACME and Road Runner thing , you've just given away your age ."

Acme was a dash air supplier , back in the day . I'll see if there is any info remaining on line , because I don't believe they survived the 08 downturn .
__________________
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Skip426 is offline   Reply With Quote
Old 05-22-2020, 07:59 PM   #6
3x5
Senior Member
 
Join Date: Aug 2017
Posts: 132
Here are a couple of pictures. The silver diaphragm in the right controls the diverter for air flow to the defrost windshield. The one on the left has a couple of tubes going to the control dial. The little gold thing between them gets very hot when the ignition is on.



I really don't have a glue what I am doing, but I would like to fix it without going into a shop.
Attached Thumbnails
Click image for larger version

Name:	DSCN0864.jpg
Views:	4
Size:	249.4 KB
ID:	286538   Click image for larger version

Name:	DSCN0876.jpg
Views:	4
Size:	170.6 KB
ID:	286539  

__________________
2005 Alpine Coach 36 FDDS
with Cummins ISL 8.9L 400hp
3x5 is offline   Reply With Quote
Old 05-22-2020, 09:00 PM   #7
Senior Member
 
Skip426's Avatar


 
Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 19,141
With both vacuum lines and electrical connections ; that ( second picture) just be the vacuum pump.

Can you trace any of the colored lines to the control head ; then back to the actuators . If the set up is anything like that Evans uses , every actuator will have it's own color of hose ( tube ).

The vacuum actuators are spring loaded to the off position .

Finished supper , looking on the net for any info that might help .
Check the wiring to the device to check for power with the key on.

EDIT: From info online , that's a " three port vacuum solenoid " still looking as to function and the possibility of a Vacuum pump somewhere in your system.

RE-EDIT: A Google search for Acme RV dash air conditioning wiring diagrams turned up a pdf that's too big to post here in the forums. One page shows a vacuum pump another a reservoir in line from the pump to the dash.
__________________
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Skip426 is offline   Reply With Quote
Old 05-23-2020, 06:50 AM   #8
Senior Member
 
c_oneil's Avatar
 
Alpine Owners Club
Join Date: Dec 2012
Posts: 399
Skip is correct, the gold component is a 3 port vacuum solenoid, aka switch. IIRC the vacuum pump you are looking for is on the outside of the firewall, drivers side, up high. When you first turn the ignition switch to the on position you should hear the pump run for 15 seconds or so. If you have the Ford style it could be part# F81Z 2A451 BA. Looks like this:

https://www.carid.com/oe-replacement...-2a451-ba.html


Could maybe be ACME brand. See A/C Parts Automotive and Motorhome for that.
__________________
Carter & Patty
'05 Alpine Limited 36FDTS + '13 CR-V
FMCA & ACA members
c_oneil is offline   Reply With Quote
Old 05-23-2020, 07:17 AM   #9
Senior Member
 
Jeep401's Avatar
 
Join Date: Nov 2017
Location: Marysville, WA
Posts: 273
Mine did the same thing when I bought it.
Like others have said, make sure the pump on the outside of the firewall is running when you turn the key on ( should be obvious). If so, then look for a vacuum tube that is broken or in my case fallen off.
One of my lines had come off the back of the switch which is very close to the pull out part of the center console which I think had pulled it out at some point while opening and closing the console. I put it back in and it's been fine ever since.

I believe the switch is from a 90's Chevrolet truck which I was able to find a diagram for online to help troubleshoot.
__________________
Angelo & Leslie
2005 Alpine 36FDDS #75268
MARYSVILLE, WA.
Jeep401 is offline   Reply With Quote
Old 05-23-2020, 07:24 AM   #10
Senior Member
 
Old Scout's Avatar
 
Join Date: Nov 2005
Posts: 5,536
What Carter said--vacuum pump and reservoir are located on outside of front bulkhead, in front of driver's position, under front cap with genset slide extended....this is an ACME system--they're out of business but the second link will get you to ACMEAIRPARTS.COM. Richard is great to talk to, knows the ACME system, and has all the parts.
The default position for the blend doors is defrost--so no vacuum.... First, I would check all the vacuum lines on outside of bulkhead....you should hear vacuum pump start with ignition on and then stop once vacuum has built. Pump may have failed but disconnected or leaking hose is more likely....
__________________
Old Scout
2003 40' MDTS
New Braunfels, Texas
Old Scout is online now   Reply With Quote
Old 05-23-2020, 10:37 AM   #11
3x5
Senior Member
 
Join Date: Aug 2017
Posts: 132
Wonderful, wonderful info! I will get to work.
__________________
2005 Alpine Coach 36 FDDS
with Cummins ISL 8.9L 400hp
3x5 is offline   Reply With Quote
Old 05-23-2020, 11:24 PM   #12
Junior Member
 
Join Date: Nov 2010
Posts: 25
Vacuum pump is available at NAPA. Choice of US made or offshore.
Pretty well requires two people to chance out pump, one under the steering wheel and another outside at fire wall to tighten bolts
Quiltlady is offline   Reply With Quote
Old 05-24-2020, 07:11 AM   #13
Senior Member
 
Jeep401's Avatar
 
Join Date: Nov 2017
Location: Marysville, WA
Posts: 273
I've been planning on moving mine to a quieter location but haven't because of needing two people. I think when I get the help I will do the Vansco bolts too!

This comes in hand for troubleshooting.

HFS (R 2 in 1 Brake Bleeder & Vacuum Pump Test Tuner Tool Kit https://www.amazon.com/dp/B00NP60URE..._WhNYEbM6SHMGM
Quote:
Originally Posted by Quiltlady View Post
Vacuum pump is available at NAPA. Choice of US made or offshore.
Pretty well requires two people to chance out pump, one under the steering wheel and another outside at fire wall to tighten bolts
__________________
Angelo & Leslie
2005 Alpine 36FDDS #75268
MARYSVILLE, WA.
Jeep401 is offline   Reply With Quote
Old 05-24-2020, 09:05 PM   #14
3x5
Senior Member
 
Join Date: Aug 2017
Posts: 132
A lot of great info. Thanks. I wouldn't have gotten this far without it.


I dug into it, but I can't find an obvious problem. I'm getting ready to find a mechanic.


I found the vacuum pump on the firewall right where you said. Thanks for the jump to the website, Carter. Mine looks just like it. So the replacement is Dorman 904-214. They are available everywhere, including NAPA and Autozone.


But I'm guessing the vacuum pump is ok. With the ignition on accessory and the heater on, the vacuum pump runs continuously. But it doesn't stop, even after two and a half minutes. I guess that means there is a bad airleak somewhere? I visually checked and traced the tubing and connections that are accessible, but I can't find anything obvious. Should I also be checking the pump somehow?


There are also two small wires, one black and one white, coming out of the vacuum pump that I guess are vacuum tubes. They go into a bundle and through the firewall near the steering wheel. But I don't see any power wires connected to the vacuum pump! (Or if those are actually power, then where are the vacuum tubes?) Since the pump runs continuously, I would like to be able to pull the power to it, and still use heater and a/c without the vent controls. What am I missing? Where is the power?


I was also thinking, I might unbolt the defrost actuator diaphragm, so the defrost vent is kept open, so air would come out the front vents instead of the defrost vents. Does this make sense? This would just be until it gets fixed.


I would like to trace the tubes out from the pump and check each connection for vacuum, but I don't know how to check for vacuum. Can I just put my finger on the end of the tube? Is there some tool? And is there some way to check the actuator diaphragms?
__________________

__________________
2005 Alpine Coach 36 FDDS
with Cummins ISL 8.9L 400hp
3x5 is offline   Reply With Quote
Reply

Tags
air, air conditioner, dash, heat, heater, vent



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Dash air blowing through defrost vents only Treetop Flyer Winnebago Industries Owner's Forum 6 09-25-2018 07:15 PM
Dash AC Defrost Mode Not Working jd956jd956 Newmar Owner's Forum 4 06-07-2017 07:46 AM
Dash A/C blowing out of defrost vents only cae2583 Class A Motorhome Discussions 3 07-19-2011 10:17 AM
ONLY dash air from defrost vents DadD45 MH-General Discussions & Problems 9 05-20-2008 03:47 PM
dash air blowing out of defrost vents? softballdad25 Workhorse and Chevrolet Chassis Motorhome Forum 5 09-03-2007 07:40 PM

» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 03:09 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
×