96 PSE Air Blows Through Defrost Vents Only, No Dash or Floor?

[$200ProbeSE]

I don't know HVAC so I'm lost on this one. Read elsewhere it could be the actual HVAC interior control problem that has the settings and knobs or it could be a vacuum leak. Any way to test this system to make sure? Anybody had this problem? What was your solution? Any help would be appreciated, thanks!

[LowClassCC]

Your HVAC panel is vacuum controlled. You need to check to make sure the vacuum line for it is hooked up to a good vacuum source under the hood.

[$200ProbeSE]

Your HVAC panel is vacuum controlled. You need to check to make sure the vacuum line for it is hooked up to a good vacuum source under the hood.

How does one go about checking it to verify that it's good? Will any vacuum line do? I'm thinking maybe replace all of my vacuum hoses since the car is about 20 years old.

[LowClassCC]

Under the hood, passenger side rear corner there is a black vacuum chamber. 2 lines connect to this. One leads inside the cabin to the HVAC panel. The other connects to a vacuum nipple on the intake manifold somewhere.

If you replace all your vacuum lines just keep this in mind. some of the lines could be stuck on the nipple pretty good. In the case of a plastic nipple on a vacuum chamber or an inline check valve these plastic nipples can break off very easy when trying to remove a hardened or stuck vacuum hose. Save yourself some trouble and heat the vacuum hose end all the way around with a lighter is it connects to a plastic nipple. By heating it up it will become softer and easier to remove which will lower your chance of breaking the plastic nipple off.

[$200ProbeSE]

Under the hood, passenger side rear corner there is a black vacuum chamber. 2 lines connect to this. One leads inside the cabin to the HVAC panel. The other connects to a vacuum nipple on the intake manifold somewhere.

If you replace all your vacuum lines just keep this in mind. some of the lines could be stuck on the nipple pretty good. In the case of a plastic nipple on a vacuum chamber or an inline check valve these plastic nipples can break off very easy when trying to remove a hardened or stuck vacuum hose. Save yourself some trouble and heat the vacuum hose end all the way around with a lighter is it connects to a plastic nipple. By heating it up it will become softer and easier to remove which will lower your chance of breaking the plastic nipple off.

Thanks I will try that. I actually do have some extra vacuum lines laying around the garage.

[electechbw]

I just bought a 1996 Ford Probe for my son and it's doing the same thing. Did you have any luck finding the problem?

[unionrdr]

I don't remember the probe dash exactly anymore, but these newer Fords had a row of vacuum pump solenoids in the dash rigged to a line or two on the engine. Each one controlled a separate function for ther heating & cooling vents. you likely have to check those.

[$200ProbeSE]

I just bought a 1996 Ford Probe for my son and it's doing the same thing. Did you have any luck finding the problem?

No I haven't. What I did until I have more time is disconnect the red, yellow, and blue vacuum lines that plug into the actuators, and since it functions like a plunger, I moved the actuator arm until the air started blowing through the forward facing vents. I never use the floor or windshield vent functions, so it's working okay for me at the moment. If I do figure it out, I will post the fix. As stated above though, I'm now experiencing a rough idle, so it's definitely vacuum related.

[LowClassCC]

Did you plug the ends or the red, yellow, and blue vacuum lines after you unplugged them?

[Greg 94 PGT]

Under the hood, passenger side rear corner there is a black vacuum chamber. 2 lines connect to this. One leads inside the cabin to the HVAC panel. The other connects to a vacuum nipple on the intake manifold somewhere.

Did you ever check this?

Over the years I have seen this dozens of times and it has always been a vacuum line hanging off, not connected to the Intake Manifold.

There is a black box between the passenger side strut and the firewall in the engine bay. Look for an empty port or hanging vacuum line. Then connect that to an empty port on the IM, or tee off another vacuum line from the IM.

Then make sure the line going from the fire wall to the box is connected. Usually it is the first one I mentioned because people will knock it off or just remove it and forget to reattach it.

[$200ProbeSE]

Did you plug the ends or the red, yellow, and blue vacuum lines after you unplugged them?

Nope. Left them unplugged and just moved the plunger arm to get the air to blow through the cabin vents instead of through the windshield vents. Just a temp fix.

Did you ever check this?

Over the years I have seen this dozens of times and it has always been a vacuum line hanging off, not connected to the Intake Manifold.

There is a black box between the passenger side strut and the firewall in the engine bay. Look for an empty port or hanging vacuum line. Then connect that to an empty port on the IM, or tee off another vacuum line from the IM.

Then make sure the line going from the fire wall to the box is connected. Usually it is the first one I mentioned because people will knock it off or just remove it and forget to reattach it.

No I haven't, I will check it today if I have time. And report back. I thought it was odd that it was working fine one day, and then stopped working the next.

[Mr Man]

Did you ever check this?

Over the years I have seen this dozens of times and it has always been a vacuum line hanging off, not connected to the Intake Manifold.

There is a black box between the passenger side strut and the firewall in the engine bay. Look for an empty port or hanging vacuum line. Then connect that to an empty port on the IM, or tee off another vacuum line from the IM.

Then make sure the line going from the fire wall to the box is connected. Usually it is the first one I mentioned because people will knock it off or just remove it and forget to reattach it.

^^this x2.

i have seen this happen with probe, escort and zx2 and it was all due to old rubber vacuum lines cracking and coming loose under the hood.

[electechbw]

So, I'm going to try to work on this project this weekend. This may be a dumb question, but are blue, red, and yellow vacuum hoses on the air flow control selector module in the car? I'm going to check all the outside vacuum hoses/fittings on the engine again, but I haven't found any leaks so far.

[KLZE Porsche]

So, I'm going to try to work on this project this weekend. This may be a dumb question, but are blue, red, and yellow vacuum hoses on the air flow control selector module in the car? I'm going to check all the outside vacuum hoses/fittings on the engine again, but I haven't found any leaks so far.

I believe they have a connector that connects directly to the back of the AC/Heat control panel.

[electechbw]

Finally got it sorted out... A vacuum hose was leaking on the engine. It was tough to find because it was right in the middle of the hose and I had mainly been focusing on the connections. There was a hole that might've been caused by it vibrating against something or possibly touching something hot and melted. Regardless, it's fixed now and A/C is now coming out of the vents. Thanks for all the input.