Blend door = recirc door?

[DoctorRoboto]

I'm trying to diagnose the problem in my '95 B3000. I have weak airflow in the cabin, and also no A/C. Trying to focus on airflow first.

All fan speeds sound like they're working, I hear the fan working even on the low speed, so I don't think it's the resistor. But the airflow is basically zero for any fan direction, upper, lower, defrost, whatever. If I use the heat, the truck will get quite warm.

The forums make it sound like the recirculation / fresh air door has fallen off and gotten lodged in the path of the air flow. I'm having a hard time confirming whether the recirculation door is different from the blend door. It sounds like the blend door actuator is not the problem. But are these the same - is there only one door in there?

What's the best order of events to test these different things? Sounds like it could be vacuum, blend door actuator, crop in the blower motor, and fallen recirc / "fresh air" door. Is there anything else this could be?

When I drove x-country, every once in a while we'd go over a bump and get really good airflow out of the vents, and then a few minutes later we'd be back to the same crappy airflow.

 

[RonD]

No they are different "doors".

Vent position and fresh/recirculate are vacuum operated
Blend door is electric and operated by Temp setting

Good diagrams here: https://www.2carpros.com/questions/ford-ranger-1998-ford-ranger-erratic-inconsistent

If there is no vacuum then vent control will default to defrost that is its "off" position, but that wouldn't effect air flow.

The fresh/recirculate door feeds air to blower so if it was obstructed then yes blower couldn't pull in enough air to get good flow
If you pull out glove box you can get access to most vacuum controls

 

[DoctorRoboto]

I've never worked with vacuum lines before - how do most people test to see if there's working vacuum?

I will go have a look right now, hopefully I can see if the recirc door is sitting on the floor of that housing. Sounds like I can just look in from underneath the glove box.

 

[DoctorRoboto]

Okay, some updates. I assume the recirc door is the one that's right in front of your face when you remove the glove box, off to the right a bit. It's directly behind the blower motor - is that the recirc door, or something else? Kind of looks like some pictures from online. Well, mine is firmly attached where it's supposed to be. First picture below, from the engine compartment looking straight back. There's some kind of vacuum driven linear actuator that goes to it that I didn't snag a picture of, white vacuum line going to it, that mechanical link is in tact as well. I can move the door open and closed by hand and everything seems to move fine. Just tried to fire up the truck (with the blower removed) and I can't get that vacuum-driver linear actuator to move at all, using any combination of knobs on the heat / A/C. I will do a test drive in a few minutes and if it changes will update.

Also, as you can see I pulled the blower motor and had a look around, once I figured out how to get the fluid reservoirs moved. The rear lower bolt on the reservoir was seized, so I had to rip that mount out of the slot in the frame - 3 out of 4 bolts isn't bad, right? Anyway, it's clean as a whistle behind the blower motor. No mice, no crud on the resistor pack (see second pic, wasn't expecting any, and I can hear varying levels of airflow when changing that speed control knob). So that's not it either. There was a tiny bit of crud on the bottom of what I assume is the heater core (see third pic), but I don't think that's the problem.

Pulled the blend door actuator, that moves fine when I turn the heat control knob. I quickly felt around in the housing and didn't think that the connection for the blend door actuator was cracked, especially since I do have decent heat (again, just dispersed). So my guess is this is the other doors - the floor/panel door, and the panel/defrost door, along with no way to control the recirc door - all of which are vacuum controlled. I also don't hear anything happening when I turn that directional control knob, which is another good indicator that something's wrong with the vacuum system.

I pulled the white vacuum port off the bottom of the linear actuator and I don't get any kind of suction / pressure from there. That's probably bad. From that diagram that was posted, it looks like this also goes to the 'water valve vacuum motor', which is probably something I want running as well. I have no idea where that vacuum line comes from - I see there's some kind of mega vacuum connector behind the glove box, all manner of colors, going into a white connector block, but I have no idea where that comes out on the other side, or if it's safe to just yank that while the truck is running and put my finger on the holes to see if there's some kind of vacuum anywhere. There's a black line running from somewhere under the blower to some kind of black sphere near the radiator, which then has a red line coming off of something on the engine and a coolant line going to the radiator. No idea what that is. I can start yanking off vacuum lines progressively closer to the vacuum source, but I have no idea where the white line actually comes from, just whatever that black line is in the engine compartment. There's a red and green pair of lines in the back of the engine compartment as well, they connect up into some housing and go to a different part of the engine. Whatever bracket those were mounted to is broken off, they're going to some black box which is just dangling behind the engine but seems in tact.

I'm going to guess that most of my problems all have to do with vacuum. This might also be one of the reasons why the A/C isn't working. Where do I start looking for the issue? And is there any good way to get some airflow in the cabin in the meantime? I ran the blower and tried holding that recirc door open, and it didn't really make a bunch of difference in terms of how much air came out, or where it came out. Air slowly oozes out of all of the different vents (defrost, low, upper) regardless of what setting I have it on.

 

[RonD]

The main vacuum for the system in the cab comes from the vacuum reservoir, it looks like a black plastic ball, it is in the engine bay, usually passenger side towards the front and low.

The Black vacuum hose the comes from the firewall goes to that vacuum reservoir.
If the system inside the cab is still hooked up, then pull off that Black vacuum line from the reservoir and suck on it, it should hold pressure/vacuum, if not then there is a leak, in that black line or in the cab.
If some one can be in the cab while you Blow into that Black line then they may be able to hear where it is leaking.
DO NOT used compressed air, you will blow off hose connections

If cab system is holding a vacuum then the vacuum reservoir is probably leaking, not uncommon for it to crack.
Hook the Black line back up to reservoir, follow the other line on the reservoir, it eventually goes to the intake manifold(vacuum source) but it often is "T'ed" with another device that needs vacuum, once you find an end for that other line remove it and do the same test, suck on that hose, it should hold a vacuum if reservoir is OK, if not then reservoir will need to be changed.
There is an IN/OUT on these reservoirs because of the check valve inside, so keep track of which hose went where.

Yes the "other" color vacuum line that comes out of the firewall into engine bay is for the Heat control valve on the heater hose, also call Bypass valve, often has 4 heater hoses connected.

Just as a heads up, I did have a blower squirrel cage come loose on the motors shaft, so it was turning but not fast, wasn't on a Ranger but was a Ford car

 

[DoctorRoboto]

I put some updates in my post about where various vacuum lines go. Anyway, I just checked out that vacuum reservoir. First off, I was wrong - there's no coolant line to it, that goes underneath it to the heater core or something. There are two lines - black and red. I sucked on the black one, it was not easy, so I assume that there's at least partial vacuum. I tried the same with the red one, but that goes right to the engine, so that didn't get me very far. I blew into the black one, didn't hear anything immediately.

There is some kind of capped check port on the front of the reservoir. Is that how people test the vacuum on the system? What device do I use to test this? A finger, some kind of vacuum gauge? Can you pull that off while the truck is running? What would I be looking for?

 

[DoctorRoboto]

Do people just get in there with something like this? http://shop.advanceautoparts.com/p/actron-vacuum-and-pressure-test-kit-cp7803/9090006-P?searchTerm=vacuum+tester

What would happen if I pulled off that white vacuum housing behind the glove box while the truck was running? Is that how I would test the vacuum at different points? Do I get in there with some vacuum line and start moving tubes around manually, like an old switchboard operator? I assume one of those connections is the inlet (maybe a black one?), so perhaps I can try to 'hardwire' the vacuum connections and see if I can get anything to move.

 

[RonD]

Vacuum system is a sealed system, meaning if you suck on the hose you can't, but it also won't allow you to slowly suck on it.

You use a vacuum pump/gauge to test vacuum device systems.
Pump up the vacuum(same as sucking on hose) then watch the gauge, if it starts to drop then you have a leak.

The one you posted the link to is more for testing the vacuum source, the engine, and is a very good tool for testing engines.

Vacuum devices, like actuators, valves and reservoirs need to be tested with a vacuum pump

Like these: https://www.amazon.com/Vacuum-Pump-Operated-Pressure-Gauge/dp/B007A0SEFQ

 

[DoctorRoboto]

Hmm, I wasn't expecting that. Picked up a vacuum / pressure gauge today in between posts. I followed a quick video to test the vacuum on the reservoir (https://www.youtube.com/watch?v=7tSFPSY19MI) and tried it on mine, and found that it does indeed hold vacuum. But what was interesting was that I put the vacuum gauge right on the mount on the engine that had the red supply line, and it is not generating any vacuum. Zero. See attached picture, that's with the truck running. Is that what's supposed to be happening? I tried revving the engine, looked to see what it would do right on startup, and nothing.

So I could go find a vacuum pump and start trying various things in the firewall, but did I stumble on a major problem right out of the gate? It's the copper colored puck right next to the oil fill port, the red hose normally connected is sitting off to the side in the picture. Would I need to do something to get this to start developing vacuum, like letting the engine run for a while, or run under load, or try turning on the A/C or something? Seems like this should have vacuum all the time, but I don't even know what it's called.

 

[DoctorRoboto]

Another quick update - I hooked up the vacuum gauge to a check port on the other side of the manifold, there was a line coming off of something similar that had a capped T, I plugged in there and vacuum looks great. It's in the green, blipped the throttle and it dropped to zero, then it overshot the green a bit and settled back in the right range. Clearly I have no idea what all of these vacuum pieces are called, but it was coming off of what I think was the EGR valve.

What is the piece that the reservoir supply vacuum is plugged into in my previous post? Is it the fuel pressure regulator? I assumed it was just a hole going to the manifold somewhere so I started taking off the two allen head bolts, and then fuel started spilling everywhere - turns out it's sitting in line with the fuel line. I have no idea why the supply for the HVAC control lines would be uniquely connected to the vacuum coming from the fuel line, with no direct source of vacuum from the manifold. Could definitely use some help figuring this one out. Shouldn't the supply for the vacuum reservoir be coming from something more reasonable, like the manifold directly? There are extra ports on a distribution block back there.

If that's true, and the vacuum is supposed to come from somewhere else, what goes on top of the fuel pressure regulator? Nothing? Does something actually pull vacuum on that normally? I'm wondering if someone just did something really stupid when they hooked all of this back up after earlier work by a PO, and maybe I'm supposed to run a line from the vacuum distribution block directly to that vacuum reservoir.

 

[RonD]

In your picture it looks like you have your gauge hooked to fuel pressure regulator, that is a vacuum device, not a source, so it will never HAVE vacuum, it NEEDS vacuum.

Vacuum source comes from intake manifold.
i.e. Power brake booster hooks to intake manifold, PCV Valve hooks to intake manifold.

You should see a Vacuum manifold, on the intake manifold
Picture here of Vacuum manifold: http://www.explorerforum.com/forums/index.php?threads/94-explorer-vacuum-line-madness-pics-inside.359540/

1st pic, has all the hoses connected to it

Thats where your reservoir gets its vacuum.
But that hose can be SHARED with another vacuum device, like the fuel pressure regulator, they just need to put in a "T".
Most vacuum devices don't "use up" vacuum, if they did that would be called a vacuum leak.

So you don't need a dedicated vacuum hose from the vacuum manifold to each vacuum device.

 

[DoctorRoboto]

Okay, good - was hoping that was the case. Somebody must have reconnected things really stupidly way back, and no shop ever caught this before. I'll hook both of these up to the manifold, which might help both get the cabin HVAC doors working correctly and will give me some more power when accelerating, and lean out the truck at idle. Very excited to see the results, will report back tomorrow.

 

[DoctorRoboto]

Success! I posted a parallel thread in the engines section about the fuel pressure regulator, to confirm that this should be getting vacuum from the IM. They advised that I not split the vacuum to the FPR, since it needs quicker response. So I sent the shortest line possible direct from the largest port on the vacuum manifold right to the FPR, and I T'd off the line from the EGR to go to the vacuum reservoir, which then goes into the cabin. Works like a charm, got my vent control back, and it's significantly improved in the cab. I knew it worked because I switched to 'panel' and a bunch of dust and some bits of old nature came flying out at me - a sign that airflow hadn't been seen around those parts in an age.

I have no idea if the FPR is working the way it should, but I have airflow in the cab now, so that's a great start. I'm sure it's better than it was, just not sure if it's working perfectly. But for now, I'll take it. Onwards, to fixing the air conditioning!

 

[RonD]

Good work

Thanks for the update and fix