HVAC Controls

[Atrum Rosa]

I had the local shop here chasing electrical gremlins, and it came back from them with a new one. This car...:spank:

The HVAC system isn't very responsive when changing vent selection. It changes to the floor vents fine, but likes to stay there. It'll eventually switch back to dash vents after some driving if the selector is left there. It almost seems like some paper or something is getting sucked up against an internal vent somewhere and blocking it. I couldn't find anything obvious in a look, but I've never really messed with the HVAC stuff in a vehicle. Any suggestions?

[techsan23]

Re: HVAC Controls

I would start by checking the vacuum lines and their connections by the pass rear of the engine compartment for a vacuum leak.

[Rob Bell]

Re: HVAC Controls

Agreed, There is a vacuum tee/check valve thing that supposedly cracks with age. Even if it looks OK, you can still remove the hose that leads into the firewall, which will be the hose that operates the vacuum HVAC controls. Attach a vacuum pump and then when you have a vacuum, try operating the controls and see if they work better.

[Atrum Rosa]

Re: HVAC Controls

Vac leak eh? My brakes are really ****ty too, possibly related?

[FIREBIRDV6RAGE]

Vac leak eh? My brakes are really ****ty too, possibly related?

The breaks and hvac are 2 different things. There's no way it can be related.

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[Docta]

Re: HVAC Controls

The breaks and hvac are 2 different things. There's no way it can be related.

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Doesn't HVAC get its vacuum from the brake booster? In a roundabout way

[Docta]

Re: HVAC Controls

And the the intake has the MAP sensor, that's got a line going to the FPR, and I think the other one goes to HVAC. And seeing as HVAC controls work without the compressor, condenser, lines, or any refrigerant... and our cars don't have air pumps.

[nascar24jd]

Re: HVAC Controls

Agreed, There is a vacuum tee/check valve thing that supposedly cracks with age. Even if it looks OK, you can still remove the hose that leads into the firewall, which will be the hose that operates the vacuum HVAC controls. Attach a vacuum pump and then when you have a vacuum, try operating the controls and see if they work better.

Exactly right.

Doesn't HVAC get its vacuum from the brake booster? In a roundabout way

No. Everything vacuum related gets its vacuum from the engine. It could be related if you have a massive vacuum leak.

And the the intake has the MAP sensor, that's got a line going to the FPR, and I think the other one goes to HVAC. And seeing as HVAC controls work without the compressor, condenser, lines, or any refrigerant... and our cars don't have air pumps.

HVAC controls have nothing to do with the A/C compressor components. The vent distribution system works off of vacuum, nothing more.

Check the vacuum line and the check valve.

[FIREBIRDV6RAGE]

What happened to my post? I had explained oh well lol but yeat ^^^^ he pretty much said what I was going to say

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[CFreed11]

Re: HVAC Controls

What happened to my post? I had explained oh well lol but yeat ^^^^ he pretty much said what I was going to say

Sent from my SGH-T999 using Tapatalk 2

I had a post "mysteriously disappear" too... And mine didn't even include any wrong information, just a question to help clarify what was being asked...

[Docta]

Re: HVAC Controls

HVAC controls have nothing to do with the A/C compressor components. The vent distribution system works off of vacuum, nothing more.

Check the vacuum line and the check valve.

That's what I was saying. I don't have any AC components and blend doors and controls work fine. I just had the vacuum source backwards.