Defrost and nothing else

[ditz256]

1998 Winstar with nothing but defrost working, blower blows but regardless of setting only defrost air comes out. additionally rear air is heat regardless of setting (no top air blowing). All fuses and relays look ok.

Would appreciate any suggestions.

[3d914]

Ditz,

Checked the same things on my 98 Limited, and nothing so far. Follow this post as well for some feedback.

Regards,

[ModMech]

Vacuum hose is off somewhere, or the selector is bad (leaking).

[steve_o]

My 1999 Windstar started exhibiting these exact symptoms after fixing the Lean Ports EGR TSB etc.

So I suspected the loose or unplugged vacuum line.

What I did find was a small tube coming from a device mounted on the firewall going to a couple of other vacuum lines connected to the intake manifold, and that tube was completely melted.

I was melted from resting on the rear valve cover or some hot part of the engine.

So I spliced it and replaced the damaged part with some tubing.

This did not fix it.

Does anyone suggest any parts I should replace or suggest way to test what is broken.

Waht is that thing that tube was coming out of....or am I on the wrong track?

I have planty of heat, but I get cold feet.

Steve_o

[12Ounce]

steve_o

You could check the pneumatic connector on the "A/C-heater function selector switch" to see if any vacuum exists there. The vacuum supply should be on port #1 of that connector... all of the other 5 ports go to 3 "vacuum control motors" at various doors in the heater/ac plenum.

[steve_o]

12Ounce

I checked at the pneumatic connector on the "A/C-heater function selector switch" to see if any vacuum exists there.

No vacuum existed there.

Maybe these items I found might help:

#1 – When I move the selector switch, I can hear a clicking noise down by the in cabin fuse box – to the left of the brake pedal under the dash. I don’t know if a fuse is involved or which one to check.

#2 – I figured out that the thing on the firewall (I mentioned in a previous thread) looks like a Vacuum control solenoid valve (saw a picture in a book). Does spinning that round knob on top do anything? Like increase or decrease the vacuum?

Any thoughts?

[12Ounce]

On #1, I don't have much to offer. There are some relays in there for the blowers... so the clicking may be normal. I would focus on the missing vacuum.

On #2: I believe you are referring to the EGR Vacuum Regulator Solenoid (9J459). This solenoid valve is pretty much unserviceable. The "knob" is merely a cover for a small air filter mesh (I think... I've never opened one).

This valve accepts a "duty cycle" signal from the PCM and, in turn, varies the vacuum control signal to the EGR valve.

[steve_o]

Any idea how to trace the vacuum that leads to the "A/C-heater function selector switch"?

Or troubleshoot the source?

steve_o

[Dngrsone]

I have a '97 3.8l so things may be a tad different.

On the hood there should be a vacuum diagram. You want to find the line marked as accessory, that's your vacuum supply line. It runs to a check valve and through the firewall. There will be a vacuum tank on the interior somewhere near the center panel. The vacuum supply lines are black.

SteveO, it looks like you found the correct vacuum line leading to the firewall that supplies the vacuum for your environmental controls. Make sure your tube didn't melt shut.

The system uses vaccum to operate motors that direct air either through the heat exchanger or around it and through the chiller for heat, AC repectively. The default (no vacuum) is for heat.

So likely the problem is lack of vacuum, usually because of a leaking control or a broken line.

[steve_o]

You were right on, it was the (black) vacuum supply line leading through the firewall that supplies the vacuum for my environmental controls.

It was melted shut, I replaced it and my toes are toasty again.

It seems that the clicking I heard was normal.

Thanks again to 12Ounce and Dngrsone.