2007 Suncruiser 38T Engine AC Vacuum Hosee Routing

F1Boat · 08-13-2022, 09:59 AM

I purchase this 2007 Suncruiser 38T RV used and am trying to troubleshoot the Engine / Dash AC.
Does any one have information on the vacuum hose routing? There seems to be one missing from the main canister ball that is getting vacuum from the engine.
I am not sure where it would go to.
The selector switch will not change from and the fan only works on high.
I think these are controlled by vacuum.
A diagram would be nice if is available.

Morich · 08-13-2022, 11:34 AM

No direct help as I'm lacking experience with AC or workhorse. But there are some really good intense online info which I can pass along as a place to start.

http://workhorse.navistar.com/Default.aspx?tabid=574

Don't skip over the line on how to decode the VIN as that can give lots of exact info on other points like the engine that you will likely need to sort the info.

From past looking at the blowers, I think of it as being a set of resisters that control the fan speed, so you may be looking at two different question?
Approach that with care as it is a really foggy memory!

jsa2000 · 08-13-2022, 12:25 PM

I seem to remember having this same problem with a 2005 Itasca. It turned out to be a firewall mounted relay. The fan would only work on one speed setting. Changed the relay and BINGO! Now if the air flow goes from vents to windshield defrost while exhilarating, then it's a broken or cracked vacuum line. Very thin running from the firewall to the air box. I think I threw away the old relay but I'll look for it and send you a picture if I find it. I bet it's the same one. Hope this helps.

https://www.youtube.com/watch?v=XpPP74UBQq0

Check this at the 2 minute mark. It's the little black relay. Take a picture of it and go to the auto parts store ofr search on line for it.

Bones2003 · 08-13-2022, 12:38 PM

That system is almost entirely Winnebago with hardly any parts from Workhorse. This website has great information about the various systems over the years and vacuum troubleshooting guidance.

https://www.proairllc.com/design-eng...empcon-guides/

Bones2003 · 08-13-2022, 12:46 PM

You can also find a little bit of information in the PDF for your 38T on about page 168.

https://catalog3d.winnebagoind.com/menu/Parts.htm

jsa2000 · 08-13-2022, 01:02 PM

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I had posted an earlier reply but it seems to have disappeared. I guess I need to get used to this as a new member. Anyhow If your fan speed selector switch is not working properly it's probably what I circled on your picture (attached fan relay). I've had this problem on my 2005 Itasca...Workhorse chassis. If your airflow changes from vent to defrost upon acceleration then it's a cracked vacuum line. Which is it?

F1Boat · 08-13-2022, 02:02 PM

Does that relay control the fan speeds?
I removed it and it felt a little warm.
Doesn't look like the auto parts stores have that one. Found one on Amazon.

I got the doors to work to distribute the air to the differ location, the door to the dash vents was stuck.

jsa2000 · 08-13-2022, 03:06 PM

Yes. Controls fan speeds. Good find on Amazon. Most chain parts stores don't have it. Found my replacement at NAPA auto parts. Hope it fixes your fan speeds. Did the trick for me.

Matt · 08-17-2022, 05:21 PM

I purchased my 2007 Itasca 38T, 24W Workhorse chassis few years ago and have always had mediocre cold air from dash vents with chassis AC on.
AC freon charge and compressor checks out fine.
Seems to be the 'blend door',,
Would a vacuum leak cause this? Fan speed works fine and selection from floor/dash/defrost works fine. Just a mediocre cool air on dash vents with AC tho. How would one recommend a fix for the 'blend door'?

Bones2003 · 08-17-2022, 07:10 PM

I don't think there is a blend door but there might be a vacuum operated water valve that lets hot coolant/antifreeze from the engine go through the heater core. If that water valve is not working properly, the cool from the A/C has to fight the heat from the engine. Easy to check by feeling the two hoses that go to the heater core with the engine at normal operating temperature and the A/C controls in various settings. That water valve is a higher failure rate item on the older RVs but could be vacuum related.

jsa2000 · 08-17-2022, 08:10 PM

When you have max ac selected feel the dash defrost outlets. Do you have air coming from there as well? Does max ac and/or regular ac vent air move to defrost outlets when you pull a grade?

Matt · 08-17-2022, 11:54 PM

Thank you for your reply and input. I will check out that heater hose valve and check the temp of heater core lines with AC on and engine at run temp.

Matt · 08-18-2022, 12:01 AM

Hello. Thank you for your reply. Air always blows from dash vents when selected and does not change to defrost vents on a grade uphill whether in regular or Max AC mode.
I will note though that MAX AC selection actually blows warmer air than regular AC. I know Max AC selection is basically 'recirculate'. Does this info help at all to diagnose issue? Seems something going on with a valve/door/vacuum line/ or perhaps as earlier person said, the heater core hose valve is not closing properly when AC is on.