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Where would this vacuum line go?


trinogt

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In my last post here in this forum, I had some heating problems, among other things...
I had a hunch today, so I dropped the glove box and had a look at the blend door. No matter what function I put the climate control knob on, the blend door never opens, whether the engine is cold or hot! I took a look under the hood and found a vacuum hose that is severed, probably a casualty of the engine swap the car lot did... Those plastic lines are quite fragile when old in Florida, as I experienced a couple days ago with my Thunderbird, when I snapped a similar line while removing the cowl to replace the power brake booster. Figured out on the first drive that the a/c would only blow out the defrost vents and nowhere else, so that line operated the climate items. Replaced it with a piece of rubber line and all is well.
I plumbed a rubber line to this broken line and ran it to a vacuum. The blend door opens! But it stays open all the time, no matter what setting, so there must be a vacuum switch somewhere that this line was supposed to run to, but I can't find it.
Here is what I see, if someone could PLEASE check their truck and look at what I see:
1998 Mazda B2500 SE

Under the blower motor (under the hood), there is a connector. Two vacuum lines come out of this connector, a black one and a grey one. The black one runs to a location underneath the washer and coolant reservoirs, pretty much in between them because you can tug the line and see it, and disappears somewhere under the fenderwell through a hole.
The grey vacuum line is the one that is only about a foot long, and it is broken there. I have no idea where it is supposed to go, and if there is a matching end for it, I can't find it, and that would likely mean a small vacuum leak on my engine.

If someone with a similar truck (Ranger in the same year range, '98-'01 might be the same) would care enough to look under their hood, I would greatly appreciate it! I can take a picture if you like.
Thank you,
Mark
 


trinogt

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Could someone PLEASE look under their hood for me?

I need to know where the GREY vacuum line goes to after it leaves the firewall, passenger side, 2.5 liter engine, 1998 B2500. Mine is broke, no idea where it went. Thanks!
Mark
 

Flat Toy

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On a 98 Ranger the grey line runs up the front of the A/C housing and over to the shutoff valve on the heater hose.
 
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trinogt

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Thank you, Flat Toy, for helping me out!
It appears that something may be missing from my truck's setup... I do not have a shutoff on the heater hoses as you describe. There is a T-fitting at the back on one of the hoses, and the hose that branches from that disappears over the head to the other side of the block. No vacuum fitting on there...

There is also a DIY-type flushing fitting for a garden hose installed on one of the lines. Beside this is a splice connection on the other hose, not sure if something else was there.
I do not know the history of this truck, other than the lot said they had this motor put in, so something might have gotten misplaced or removed when they did the swap...
Here are some pictures to show you what I have. Hopefully you can tell me what's missing: The grey vacuum line is sticking up in the air so you can see it.


 

Flat Toy

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I have pics of mine but Photo Bucket won't let me copy them for some resound. In the first pic where you have the flush port on one line and the union on the other I have a vacuum operated shut off valve that is controlled by the grey line you are describing.
I will keep trying to post the pics I have. It was one year ago yesterday I got that account and maybe it is only free for a year?
I would try plugging the line you have and see if the blend door will work. Could be losing to much vacuum to let the door operate.
Lets see if this works!



Intake hose moved for better view
 
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trinogt

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Gee, now THAT makes sense! I don't have that part... I had no idea the grey line SUPPLIED vacuum... When I provide vacuum to that line is when the blend door closes and stays closed on all settings... Makes sense that whatever closes the blend door also supplies vacuum to the heater hose shutoff... I am thinking the owner was trying to get more heat... Go figure, it's in Florida! lol Musta thought it was a blockage point.
Off to the junkyard I go to find that shutoff valve. Looked at maybe 4 Rangers and B2500's, but none had the same setup as mine.
Thanks for taking the time to take those pics and show me what you have! I hope I can help you some day... Your generosity has been unparalleled.
Mark
 

Flat Toy

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I would of guessed they broke the valve and used what they had on hand to make it work.
 

trinogt

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Hey Flat Toy...
I capped off the grey line and tried the a/c... Well, it finally DOES CLOSE the blend door when I switch to MAX AC! I can clearly hear the blower get louder going from AC to MAX AC as the blend door closes. It surely must have been a vacuum leak with the setting on MAX. Now, what other settings are supposed to close the blend door? I tried all other settings but nothing else will close it. So, it seems to me that the grey hose is AC related and not heat, as it only closes the blend door (provides vacuum) in MAX mode. It makes sense to shut off the flow of hot coolant when it is not needed in the summer. Now, I just need to figure out what causes the lack of heat in the truck. Might just be a case of heater core blockage, as one hose gets much hotter than the other. I heard it's a bear to change the core because the whole dash must come out... Not a big deal living in Florida though... If I were back in Western Canada, I would be doing it now! lol
 

Hardwareman

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I'm having the same problem with my A/C and the line's disconnected as well!

I'll try capping mine off tomorrow and see if I have any luck. Thanks for this post.





Allen
 

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