Hvac in my 1990 Cabby

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ED-EX
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What year is your cabby?: 1990
Do you own a Cabriolet?: Yes

Hvac in my 1990 Cabby

Post by ED-EX » Sat Nov 27, 2010 11:38 pm

I am having a problem trying to figure this out. I know about the Hvac system, how it's routed, servos, which are the heat vents and colds vents. No problem with A/C or Heat coming out. The problem is air coming from top vents only, no center or floor vents. Read on how to check and I did all the checks. The problem comes when I remove the check valve and plug it in direct, from engine. Go inside top vent works when set at that. Center vent and floor work when set to it control setting. Thought it was that check valve had to buy from VW. Worked for about a week then back to the same. Anyone know whats going on? Thanks ED.

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Briano1234
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Re: Hvac in my 1990 Cabby

Post by Briano1234 » Sun Nov 28, 2010 5:44 am

I had a similar thing happen to me been fighting it off and on for a few months.

What was causing my issue was that the vacuum control unit mount tab had broken. so that when I was selecting a different vent flow, it would move the slider and then the slider would push the assembly


I have take the vacuum control unit apart and cleaned the rubber and sanded the plastic part smooth........,then applied a little bit of Vaseline to it before re-assembly.
Briano

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ED-EX
Posts: 5
Joined: Wed Apr 21, 2010 9:01 pm
What year is your cabby?: 1990
Do you own a Cabriolet?: Yes

Re: Hvac in my 1990 Cabby

Post by ED-EX » Sun Nov 28, 2010 12:06 pm

Thanks Briano, you mean the panel control unit, inside the car where you change to what vent you what to work, upper, center or floor?

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Briano1234
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Re: Hvac in my 1990 Cabby

Post by Briano1234 » Sun Nov 28, 2010 12:54 pm

Yes, the heater control unit, is where you have the selector rods. I have also seen where the plastic slide that controls the thermostat of he a/c pop out, then it will bind the heat a bit, but that is a different issue.

I would also re-run new vac hoses in the engine compartment.
Briano

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You can lead a user to a link, but you can't make him Click.... :screwy:

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gull
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Re: Hvac in my 1990 Cabby

Post by gull » Sun Nov 28, 2010 9:19 pm

I have also had the little plastic slider that connects the valve to the lever pop loose. Then you get no control.

Have you taken a Mity Vac or similar, pulled vacuum on the system, and made sure you don't have any leaks?

I've also had check valves freeze up in cold weather, although not on VWs. I imagine on a VW engine heat would thaw it out pretty quickly, because of its location.
VW fan who fell to the Honda side of the force
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Briano1234
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Re: Hvac in my 1990 Cabby

Post by Briano1234 » Sun Nov 28, 2010 9:45 pm

gull wrote:I have also had the little plastic slider that connects the valve to the lever pop loose.
I have the fix for that....

Take a small washer and pry the control arm off the plastic slide.
Remove the slide from the thermostat.
Place a thin washer 1/16 or so on the Thermostat rod, replace the slide on the thermostat adjuster rod so it is not sticking up further than normal.
Replace the control arm back in the plastic clotted slider.

It shouldn't pop off again. I have had 2 assemblies do that.... and I fixed both with that fix.
Briano

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gull
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Re: Hvac in my 1990 Cabby

Post by gull » Sun Nov 28, 2010 11:25 pm

Clever fix! I haven't had it happen again, though, so I suspect someone knocked it loose during a radio install or something.
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ED-EX
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Re: Hvac in my 1990 Cabby

Post by ED-EX » Mon Nov 29, 2010 11:08 pm

Wow thanks everyone, I'll have to check all this out and I'll you know what happens. Gonna have to tackle it soon, getting cold out there.

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gull
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Re: Hvac in my 1990 Cabby

Post by gull » Tue Nov 30, 2010 1:14 am

Good luck. Let us know what you find.

I need to fix the HVAC on the '88. I haven't hooked it back up to the vacuum system yet because it leaks vacuum really badly when the lever is in the dash vent position. I need to figure out exactly where the leak is.
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ED-EX
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Joined: Wed Apr 21, 2010 9:01 pm
What year is your cabby?: 1990
Do you own a Cabriolet?: Yes

Re: Hvac in my 1990 Cabby

Post by ED-EX » Tue Nov 30, 2010 1:59 pm

Ok folks I started with the small rubber pieces in engine area and replaced them. Checked the controls inside, everything working well. It's happened before so I gonna keep a eye on it to see if that was it. The rubber pieces I replaced were pretty old and brittle. Thanks to everyone for your time and advise. I'll get back after a while to see if this was the problem if not I'll have to take that dash off and check the controls and servos.

ED-EX
Posts: 5
Joined: Wed Apr 21, 2010 9:01 pm
What year is your cabby?: 1990
Do you own a Cabriolet?: Yes

Re: Hvac in my 1990 Cabby

Post by ED-EX » Thu Dec 09, 2010 12:09 am

Ok folks that seems to have been my problem. The rubber pieces replaced at engine area. Still working well, thanks to everyone again. ED

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