I have a 2000 Ranger 2wd 4cyl that is my daily driver. I have a problem with the air flow randomly going to defrost ducts. It happens most when I have A/C set to full fan and Max. It may be just that I notice it most then. Any ideals on what I should check? Has anyone else had this problem?

 

he i have the same problem... its that black box thats behind your glovebox that needs to be replace, ive heard its like 300ish becsaue they have to take the whole dash aprart to get to it...



heres my thread for some info if you wish...

https://www.ranger-forums.com/forum2...ad.php?t=25791

 

Fortunately my problem isn't that complicated and it works most of the time. I did see by reading yours that it is vacuum controlled. I was hoping it was soleniod controlled.

 

yea its confusing, if you take it in, let me know what it was because it might give me some more options...

 

YEah that can be a problem. Also Does it happen mostly when you are under wide open throttle? The reason I ask is I had a buick in High school that when you floored it (Not that I would ever do that! ) would lose all the vacuum and thus change the direction the air came out from the floor to the vents. It would go away as soon as the engine slowed down a hair and built up a little more vacuum.

~HJ

 

I do notice it most at highway speeds and around here it's very hilly, so could be. I wonder it an auxillary vacuum pump would fix it?

 

The defroster door is operated by a vacuum servo. The servo defaults to defrost when the vacuum drops. So, If you have this problem, it is most likely caused by a vacuum leak underhood at either the vacuum reservoir or the vacuum lines going to and from the reservoir. There is a check valve built into the reservoir to keep the vacuum from dropping off at WOT. If you can't find anything under the hood, it is also possible that there is a vac leak under the dash in the lines going to the servos.

 

you know of any way to detect where a leak could be bob?

 

You can detect the leak by spraying carb cleaner while the engine is running and listen for a difference in idol speed. I wonder where the vacuum canister is though?

 

You can usually see the damage or hear it hissing. If there's nothing obvious, a hand vacuum pump could be used to check different sections of the vacuum supply to the A/C. That could narrow down the location of the problem so you can check it more carefully.

 

The vac reservoir is under the engine air cleaner housing. It's a black plastic sphere about the size of a softball.

 

ok another thing bob... my vacuum gauge sits at 19-20 at idle... normal? or is it low meaning a leak? or would it not even matter waht that says because unless im on the leaking line, i wont detect it?

 

Yeah, I found it and everything appears to be ok. I just checked with starter fluid. I also have a problem with insufficient EGR flow. I bet they are related. I replaced the EGR valve and that fixed it for a month or so, then the sensor at the back and that fixed it for a month or so. The light came back on and I've been ignoring it.

 

That would be about right at your altitude in neutral or park.

 

im 99% sure the insufficant flow is the dpfe sensor, i had the same code and it fixed it but the vents still dont work....

but would that rule out a leak then?

 

The insufficient EGR flow code is usually due to a faulty DPFE sensor. EGR flow cannot affect the vacuum to the A/C.

 

I replaced item 3 first, then item 2 twice and most recently item 1. I think you are referring to item 1 as DPFE? I know item 3 is EGR valve and item 2 is idol control valve.

 

Not necessarily. There is a restrictor orifice in one of the ports to the reservoir. A vacuum leak could drop the vacuum level in the A/C lines without causing a big drop in engine vacuum. Besides, many vacuum gauges are only accurate within a inch or two anyway.

 

Vacuum lines go to the EGR sensor (if I'm not mistaken), so if the entire system has low vacuum wouldn't that cause both problems?

 

Yes, that looks like the DPFE.

 

I am reasonably sure that the two vacuum sources come from separate ports on the intake manifold. For it to be that low at both ports, the manifold vacuum itself would have to be very low. If that were the case, I think that you would have major idle quality problems and/or stalling. What I'm talking about is very low vacuum in the small A/C control vacuum lines because of a local leak there.

Also, are you sure that your current CEL is related to the EGR system? Has the code been pulled again since the CEL returned?

At any rate, I am here and you are there with the truck. You stand a much better chance finding the problem than I do.

 

I have checked the code and same problem. I'm going to swap the DPFE sensor again and see if or how long that will fix it.

 

Since you have already replaced the DPFE, I would take a look at the two hoses that run from the DPFE to the EGR tube and then check the EGR tube itself for any obvious problems. Any leak would cause flow measurement problems for the DPFE.

 

I checked all that last time. The sensor is still under warranty, so I'll try that. I guess the next stop is to pull the tube off and inspect it again. It was a real pain to line up when I replaced the valve.

 

i have having a problum too.....my A/c blows out the deforster also but when i put it in 4x4 and then turn it off it works....i do not know what to check and i would really like to find out cuz it gets up to 110 here and its hummide as hell......any1 have any ideas??????