Anyone had a HVAC Vacuum Servo (motor) fail?

[bizee]

I had another thread going where I was documenting my A/C troubleshooting woes pn a 2001 Itasca Suncruiser (F53) and concluded I probably had a failed heater core valve and a door that wasn't working correctly due to my vacuum leak. As it turns out I was right on both accounts, but wrong on the how.

I thought the leak was coming from the dash selector switch itself (max ac, ac, vent, defrost, etc) because I could hear the hiss from the switch. After thinking it through again the reason I heard the hiss was because of the airflow passing through it because the line that was suppose to be taking a vacuum was leaking. So the switch it fine after all.

The line that is leaking is the blue one that is responsible for Max AC (operating the recirc door). I traced the vac circuit to see that the heater core shut off valve it spliced into the blue line also. So the only time the heater core is shut down is when Max AC is engaged. Since my blue line was leaking it was allowing the heater core to stay open and not operating the recirc door.

Now when I say "blue line" I mean the that circuit... so far my tests have shown the line is good. I tested it by pinching the line off next to the vacuum motor (servo) on the airbox and the leak stopped.

So I'm now thinking it is one of these two things:
1) The door that vacuum motor operates it stuck in a halfway position or something like that allowing for a leak to occur.
2) The vacuum motor itself has a leak in.

I would normally just buy the replacement and give it go, but there are two issues I'm having. The first is it looks like it is tough to gain access to that airbox. I really don't want to have to try to get into if I don't have to.

The other is I can't be sure what part to order. The diagram Winnie has on their site shows airbox that looks very close to mine, but there is no vac motor in their diagram where mine is. In their diagram they show it near the bottom of the airbox towards the firewall, but mounted on the side of it closest to the driver.

The vac motor on mine in located at the bottom of the airbox going through the housing towards the front of the box and near the passenger side of the box.

I will call Winnie but I'm afraid their techs will refer to the drawings and parts list like I am so I fear I won't get an informed answer. This is why I wanted to see if any one hear has dealt with that servo or been inside the airbox.

I also wanted to see if anyone knew if they were servicable or if you have to replace them. Any tricks to getting one working again like applying a strong vacuum or positive pressure?

[tderonne]

I replaced one on mine. Same one, the one that does the max AC recirc door. On mine it's pretty exposed to wheel splash from the right front tire. Old servo can was frozen up, full of rust.

I found replacement ones through Winnebago or maybe Victory Climate Systems. (Original supplier, SCS Frigette being out of business.) I didn't buy from them though, I just looked around in Google images until I found something close and grabbed one at a junkyard from a Jeep Cherokee. It wasn't an exact fit, but I made it work.

You can see the servo on this picture from a Journey:


But I think you know where it is. It's not exposed to the tire like it is on our F53 setups.

Not sure if this is the right one, but should head you in the right direction:

Vacuum servo from Victory

[bizee]

Thanks for the reply. I found the replacement part on one of suppliers but it won't be here before we leave so I'm hoping I can service it. I found a couple sites where people have basically opened the crimp on the can and repaired the rubber. I'm hoping it can be a short term fix.

Do you remember how easy it was to get it out? I'm looking at the airbox and there are clips and screws holding the cover on but then there looks to hoses semi-permanently installed because they put a bunch of sealant around them and the covers.

I guess I just need to start taking these apart and see how it goes. I found a couple common motors for Ford/Motocraft that really look almost identical from the pics. If I get my bad one out I may take it with me to Autozone and see if I can find a match. It seems to be a really basic one (just up and down, single action) so the only thing that should matter is the length and shape of the arm but I can probably modify that also.

[bizee]

Nevermind... I was looking at it at night with a flashlight and couldn't see it well. Today I got underneath and could see the motor is mounted outside of the airbox so it is easy to access.

I was that was the problem though. After getting underneath I was trying to inspect the pivot on the other side to make sure the door was not stuck and low and behold there is a large section of plastic missing from my airbox. Something flew up in there and cracked off about 25 sq inches worth of housing, including where the door pivots.

Short of replacing several pieces of housing I'm left with either just locking it in place to recirc and plugging off the vac line (so the heater valve will still work) and sealing the box up with aluminum tape or buying some plastic sheet and trying it repair it by epoxying in replacement pieces.

What a bummer... I don't have much time before leaving so I think I'll need to just temp fix it.