HVAC vacuum issue?

HVAC vacuum issue?

Postby Devo [OP] » October 25th 2020, 10:54pm

Hi Astrosafari . I’ve been working on my HVAC system and have gotten it pretty close to perfect except for a misdirection of air on floor mode. All modes work as they should except for floor. On floor mode there is some bleed through into the drivers side of the dash defrost. There also seems to be a little less force at the floor when it turned from cool to heat.
All engine bay vacuum system has been proved to hold vacuum, incl heat control valve and ball. I put vacuum on the line going into the firewall and there is a slow loss of vacuum.
I suppose the next move is to get in behind the dash and start proving vacuum lines and actuators. I was wondering if anyone had any tips on best way to get at all the lines and actuators.
I have used these sources that I found using this site and others.
https://sites.google.com/site/astrosafa ... ac-airflow


Thanks
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Re: HVAC vacuum issue?

Postby sixsixsixsix is online! » October 26th 2020, 2:16pm

Devo wrote: ... gotten it pretty close to perfect


Cool, Hot and Welcome !!
.

Well, after all... what would Banacek say ?... “May be hard to believe... President Trump should rest easy and concede what was in fact a foregone conclusion: Another OLD MAN won with only about 50% of the Change Believers/Fools showing up."

.
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Re: HVAC vacuum issue?

Postby AstroWill » October 26th 2020, 7:03pm

Devo wrote:All engine bay vacuum system has been proved to hold vacuum, incl heat control valve and ball. I put vacuum on the line going into the firewall and there is a slow loss of vacuum.
I suppose the next move is to get in behind the dash and start proving vacuum lines and actuators. I was wondering if anyone had any tips on best way to get at all the lines and actuators.
I have used these sources that I found using this site and others.
https://sites.google.com/site/astrosafa ... ac-airflow


Yep, gotta get in there and test. It's easiest to start at the line that goes through the firewall to the control switch. Most of your diagnostics can be done directly at the switch using a vacuum pump w/gauge.

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Re: HVAC vacuum issue?

Postby Devo [OP] » October 27th 2020, 6:29am

Thanks will. I plan on getting in there this week. I am suspecting the problem to be defrost actuator or line pulling it closed. Hopefully it is the line. But if it’s the actuator, does anyone know a part number for this? I have looked around: ac delco, rock auto, gym parts direct, autozone, Amazon. I’ve only found the electric temp control actuator.
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Re: HVAC vacuum issue?

Postby AstroWill » October 27th 2020, 2:03pm

With these it's probably going to be a junk yard treasure hunt.

Trolls take away from productive work, best to ignore them & go about your business.
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Re: HVAC vacuum issue?

Postby Devo [OP] » November 1st 2020, 4:59pm

Thanks astrowill.

I have gotten in and tested with my vacuum tool and have proven all functions. I can make the defrost door move through maximum range. Yet I still have bleed through to defrost when on floor mode.
So I think that perhaps the seal on the defrost door is getting hung up or has failed.
Is this area a real pain to get to? Can you get to it without pulling everything apart?
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Re: HVAC vacuum issue?

Postby AstroWill » November 1st 2020, 5:10pm

Some bleed through/mixing is expected, it's designed that way.

The actuator isn't hard to get to, but I'm pretty sure that to open it up and get to the door would be a bear.

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