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Old 07-06-2017, 08:22 AM   #1
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Vacuum Pump Issues, '05 Itasca Meridian Cat 350

Just got back from a 3 week trip to West Texas ( Yes we know it was crazy to go there in the summer, but we had our reasons). During the first few days of our travel, the dash air volume began to decrease. I had to turn the fan on high to get any flow out of the vents facing us.

Going back in time a little, about 8 or 9 months ago my DW mentioned that she was hearing the vacuum pump running more than normal. I just assumed that it was getting weak and I would eventually have to replace it.

In the blistering Texas heat, I did not feel like crawling under the motorhome so we continued to run the house air. That's when I discovered that the missing air flow was coming out of the defroster vents under the windshield. Turning on the ceiling mounted defrost fans blew some of that air towards us passengers, enough to keep us from roasting. The temperatures during this time were hovering near or above 100 degrees.

So fast forward to today. I finally decided to attempt to solve the problem. I read all the forum information I could find. I found some ideas on what to test, but no luck. The biggest thing was trying to find information on where things were routed. So I'm posting some pictures to help the next guy.

I first attempted to remove the vacuum pump, because after testing some the problems other folks found, I found no leak. But, I could not reach all the screws that attached the vacuum pump to the frame. Which was good because it forced me to do my own trouble shooting.

So first I located the vacuum reservoir. Removing the black hose going to vacuum pump, I turned on the ignition to make the pump run and found that it was drawing a good vacuum. Reconnected that, then removed the black tube going to the vacuum manifold and found the vacuum reservoir had no leaks.

Then I removed the dash cover to find the AC control vacuum manifold. Using my finger nails I squeezed each tube individually until the vacuum pump stopped running. In my case it was the blue tube leaving the vacuum manifold.

It turns out that blue tube has a splitter that connects another blue tube and a green tube. The green one goes to the vacuum actuator for the heater control valve. The blue one goes to the vacuum actuator for the air conditioning air flow dampers.

I finally narrowed it down the blue tube. I feared that the air flow damper had gone bad and knew it would a pain to remove and replace it. As I was attempting to remove the blue tube from the air flow actuator, it almost crumbled in my hands. A section of the blue tube near the air flow vacuum actuator had worn away and produced a long slit. Fortunately, there was enough extra tubing stuffed up in the dash that I was able to pull out about 8 inches and cut out the part with the slit in it.

Now everything works again.

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Old 07-06-2017, 09:06 AM   #2
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I jab the exact same problem in the exact same place two years ago. I ordered a replacement plumbing harness and this year while having other work had it replaced. Yes, I was lazy. I let someone else replace the harness. Didn't want to fight the through the bulkhead wall.
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Old 07-07-2017, 10:12 AM   #3
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Vacuum Pump Issues, '05 Itasca Meridian Cat 350

Great write up. Do you know if any air should becoming out of the defroster vents in either AC mode? I live in TX and found quite a bit of air coming out of the def vents with the AC on. Sounds maybe similar issue (2007 Journey 36G Cat 350). I am getting some cool air out of the dash vents but seems like it should be more.
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Old 07-07-2017, 04:16 PM   #4
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Vacuum pump issues

Markhbike. Air coming out defrost vent on dash usually means dash vent actuator is leaking vacuum. Follow green vacuum line to actuator and remove right angle rubber connector. Connect green line to actuator with piece of new rubber vacuum tubing. Rkl
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Old 07-07-2017, 07:00 PM   #5
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Quote:
Originally Posted by markhbike View Post
Great write up. Do you know if any air should becoming out of the defroster vents in either AC mode? I live in TX and found quite a bit of air coming out of the def vents with the AC on. Sounds maybe similar issue (2007 Journey 36G Cat 350). I am getting some cool air out of the dash vents but seems like it should be more.
That was a great write up!

Incidentally, it has been a long time federal automotive rule that a faulty venting or comfort system defaults to a defrost situation. For obvious reasons of safety. Anytime you have excess air coming out of the defrost vents when the comfort controls are set for something else indicates a vacuum leak somewhere in the system. Or a blocked flapper issue.
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Old 07-09-2017, 05:56 PM   #6
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Quote:
Originally Posted by RKL View Post
Markhbike. Air coming out defrost vent on dash usually means dash vent actuator is leaking vacuum. Follow green vacuum line to actuator and remove right angle rubber connector. Connect green line to actuator with piece of new rubber vacuum tubing. Rkl


Thanks RKL, I found a strip of the tubing was totally falling apart. I replaced it as you suggested with some rubber vacuum tubing. The defroster air flow is reduced some but still has some flow. I pulled the hose off the reservoir and the pump started, stopped when I put it back so it doesn't seem to have additional leaks. I might have damper issues.
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Old 07-10-2017, 09:09 PM   #7
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Something I should look into also As more dash air would be a great plus
I do notice an increase of volume and noise at times during de celeration
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Old 07-11-2017, 03:45 PM   #8
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Journey Cat, The vacuum to run this system comes from an electric pump by the generator not the engine. This is assuming you have a DP.
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Old 07-11-2017, 03:52 PM   #9
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Great pictures and info , this post will probably be added into the stickys , for those of us with similar Evans/Tempcon dash HVAC systems.
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Old 07-11-2017, 08:31 PM   #10
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Quote:
Originally Posted by markhbike View Post
Journey Cat, The vacuum to run this system comes from an electric pump by the generator not the engine. This is assuming you have a DP.
I will look into that . Now that I know the name of the system .
Yes its an 05 Winnebago Journey W 350 Cat
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Old 07-11-2017, 09:29 PM   #11
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Originally Posted by Journey cat View Post
I will look into that . Now that I know the name of the system .
Yes its an 05 Winnebago Journey W 350 Cat
I have a '02 Journey with a 330 Cat and the vacuum pump is a little thing under the front hood, on the right side as you're looking inside. It's about the size of a water pump for a fish tank. Has a little aluminum manifold with vacuum pipes about 1/4" in diameter coming and going from it.

In my case, and my friends '04, there was a cracked section of vacuum hose under the hood up near the left side. There's a roundish vacuum actuated control there on the firewall.

Usually, if you turn the comfort control 'On' for heat, and switch the start key for the RV to ACC, that little pump will run. You can hear it running from the driver's seat and can have someone spot it for you. If it runs continuously, than you have a big vacuum leak.
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Old 07-11-2017, 10:06 PM   #12
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Thanks Jim for that info
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Old 09-25-2017, 09:58 AM   #13
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Same problem different solution - sort of.

Had vacuum pump problem as well. Installed new manifold with no change with problem. During GNR had factory look at it. They replaced a tube (think it was the blue one) and found a small freon leak at the hose connection going to the condenser. They said it would be around $900, but, a temporary solution would be to try some feron with stop leak. So far so good. Leak detection dye shows very little leakage. Keep a new can in the unit just incase.
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Old 08-15-2019, 07:40 PM   #14
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2007 Meridian 36G

Thank you so much for the explanation which is much more in detail than expected. Thanks again, Bill

Quote:
Originally Posted by fputnam View Post
Just got back from a 3 week trip to West Texas ( Yes we know it was crazy to go there in the summer, but we had our reasons). During the first few days of our travel, the dash air volume began to decrease. I had to turn the fan on high to get any flow out of the vents facing us.

Going back in time a little, about 8 or 9 months ago my DW mentioned that she was hearing the vacuum pump running more than normal. I just assumed that it was getting weak and I would eventually have to replace it.

In the blistering Texas heat, I did not feel like crawling under the motorhome so we continued to run the house air. That's when I discovered that the missing air flow was coming out of the defroster vents under the windshield. Turning on the ceiling mounted defrost fans blew some of that air towards us passengers, enough to keep us from roasting. The temperatures during this time were hovering near or above 100 degrees.

So fast forward to today. I finally decided to attempt to solve the problem. I read all the forum information I could find. I found some ideas on what to test, but no luck. The biggest thing was trying to find information on where things were routed. So I'm posting some pictures to help the next guy.

I first attempted to remove the vacuum pump, because after testing some the problems other folks found, I found no leak. But, I could not reach all the screws that attached the vacuum pump to the frame. Which was good because it forced me to do my own trouble shooting.

So first I located the vacuum reservoir. Removing the black hose going to vacuum pump, I turned on the ignition to make the pump run and found that it was drawing a good vacuum. Reconnected that, then removed the black tube going to the vacuum manifold and found the vacuum reservoir had no leaks.

Then I removed the dash cover to find the AC control vacuum manifold. Using my finger nails I squeezed each tube individually until the vacuum pump stopped running. In my case it was the blue tube leaving the vacuum manifold.

It turns out that blue tube has a splitter that connects another blue tube and a green tube. The green one goes to the vacuum actuator for the heater control valve. The blue one goes to the vacuum actuator for the air conditioning air flow dampers.

I finally narrowed it down the blue tube. I feared that the air flow damper had gone bad and knew it would a pain to remove and replace it. As I was attempting to remove the blue tube from the air flow actuator, it almost crumbled in my hands. A section of the blue tube near the air flow vacuum actuator had worn away and produced a long slit. Fortunately, there was enough extra tubing stuffed up in the dash that I was able to pull out about 8 inches and cut out the part with the slit in it.

Now everything works again.

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Old 08-15-2019, 09:01 PM   #15
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Nice. Thanks for that. Looks suspiciously like my '02 Journey stuff.
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