A/C, blower motor runs, no air from vents except defrost vent.

[BadaBingM3]

Ok fella's, hopefully someone can lead me down the right path. Today I go to turn on my A/C and I can hear the blower and air blowing, A/C pump, etc. all works. But no air flow coming from the dashboard vents. Only cool air coming from the windshield defrost vent. I couldn't check the foot vents but later in my garage I felt air coming from down there too. So tried a new relay per the manual, I tried to here if the barrel looking blower motor in the engine compartment was coming on and it is, and works at various speeds (1-4). But again, no air coming from the center and side vents but I can feel a little cool air. I started looking in the chilton manual I have from Autozone and it's not much help. It looks like in order to get to the internal blower, I'd have to remove the entire A/C system meaning the condenser, discharge the system, remove the blower motor housing and windshield reservoir in the engine bay just to get to it? How can I check to see if it's just the internal blower motor or/and the control that sits bolted to it? From the glove box looks like I can not remove it without dissembling the entire dash consul. What a damn job!

 

[lobo411]

Vacuum leak. "Defrost" is the default position when there's no vacuum to drive the vacuum motor into any other setting.

No air out of dash only defrost

 

[BadaBingM3]

Uh, wow I would have never guessed a vacuum leak for this issue. Thanks. So looking at other posts and diagrams, there are vacuum lines going to the internal blower I'm guessing? And it could be from that globe looking thing under the passenger wheel well? What the heck is that globe anyway? Can't find it anywhere in the maintenance manual. Also, I wonder how the hell a vacuum line just came loose or broke? I'll have to start digging into it. By the way, besides the obvious of a broken vacuum line, If I find it, how else can they be tested? Thanks for the quick replay.

 

[koda2000]

Vacuum leak. A vac leak anywhere will cause the same issue. The vacuum lines inside the cabin are silicon, so they're pretty durable. The ones under the hood are plastic and get brittle with age. Even a bad PCV hose, evap emission leak, or bad power brake booster can be the source of a vacuum leak. I'd start by checking all vacuum lines under the hood (engine to ball and ball to whatever). Has any work been performed under the hood lately? If a vac leak is large enough it will set the CEL w/P0171/174 codes, so if your CEL isn't on it's a relatively small leak.

There are any places that a vac leak can occur, including any vac motors inside the cabin or under the hood.

 

[Craigerz]

The globe holds a reserve vacuum so you have a constant vacuum available at all RPMs. They are pretty durable but mine came loose and had a hole rubbed in it. I tried to bypass it but that caused all kinds of problems.

 

[BadaBingM3]

Well I have done a lot of work to this explorer. During a DIY camo repaint (actually came out pretty good!) I found that vacuum reservoir. Had to bolt it up to the panel above the right front wheel well as it was floating around. This explorer was in some sort of front end collision before I bought it in 2011. Anyway, those vacuum lines looked ok. Earlier this year in January blew off a rocker arm off the front right exhaust valve so had to rebuild the rocker arm assembly and that required a top end rebuild down to the lower manifold. I did at the time have a check light and one of those codes brought on the possibility of a vacuum leak. Fixed all that. So I find it strange I have another vacuum leak but possible for sure. So in the next few days I'll start looking under the hood, the vacuum ball and passenger lower area of the dash, maybe something got kicked I didn't see? But if there are no broken or disconnected vacuum lines (right now I have no engine check light for any codes). What's my next option?

 

[J_C]

You could hook up an OBD2 scan tool capable of showing live data and look at the long term fuel trims. With a vac leak they'll be going positive, pull the vac line off the intake and plug the hole and they should return to (nearer if not perfectly) normal 0 trim.

It's a vac line or vac actuated motor, or the door it operates is bad. If you can't find the line off or damaged anywhere then you could pull it off the vac motor and see if it's pulling vac there, and pull the line to the engine off the dash selector switch and check for vac there. Keep in mind that even silicone vac lines can get brittle and crack apart if you try to pull them off where they've sat for 19 years.

 

[koda2000]

There are several vacuum motors under the dash, they control air direction. There are also other vacuum operated devices under the hood (eg: EGR, brake booster, heater control valve). You can purchase a vacuum tester (a gauge attached to a small hand operated pump) at Harbor Freight for cheap, or at any auto parts store. You can attach this to the various devices/vacuum motors and see if they will hold vacuum. If they do not they have a split diaphragm and will need to be replaced. You can also check the various lines looking for leaks.

You can also have a smoke test performed.

 

[Craigerz]

Pull the EATC unit out. It’s about as hard to pull as a radio. There is a rubber connector on the back with 5 or so vacuum lines running in and out of it. Pull that off crank it up and put your hand over it and you’ll be able to tell if you’re getting vacuum up to there.

The black ball has a check valve in it that might be stuck closed after so many years. You can pull the the lines off of the globe and plug them into each other to check it also. The AC won’t work unless you’re just idling but it will give a you yes/no on the globe.

You can check the motors that were mentioned above for a simple and obvious check. Pull down the glove box and see if the fresh air inlet is opening. The valve on the heater hose that shuts off the water to heater core is another easy one to find and look at. (I doubt they are working but it’s still an easy check) They all work off a vacuum.

 

[Turdle]

Putting this in here in case you haven't seen it, and for others searching

How to: - 2nd Gen NO AC ( or heat) FROM VENTS!!! A "How to" what to look for thread

 

[BadaBingM3]

Well I took a quick look at the brittle plastic vacuum lines coming off the vacuum ball by the passanger area of the engine bay and long behold, found one vacuum line snapped and the end of it was melted. Had to been touching something. So in a few days will tear into it and replace all those brittle lines, after I fix that one and see if that was the issue in deed. I'll report back. Thanks for the help fella's!

RB

 

[koda2000]

Well I took a quick look at the brittle plastic vacuum lines coming off the vacuum ball by the passanger area of the engine bay and long behold, found one vacuum line snapped and the end of it was melted. Had to been touching something. So in a few days will tear into it and replace all those brittle lines, after I fix that one and see if that was the issue in deed. I'll report back. Thanks for the help fella's!
RB

I have little doubt that the broken line is your problem. It takes a surprisingly small leak to mess with the HVAC controls. For a quick fix I've spliced in a short length of appropriately sized rubber vacuum line, but replacing the brittle line is the best repair.

 

[donalds]

There are several vacuum motors under the dash, they control air direction. There are also other vacuum operated devices under the hood (eg: EGR, brake booster, heater control valve). You can purchase a vacuum tester (a gauge attached to a small hand operated pump) at Harbor Freight for cheap, or at any auto parts store. You can attach this to the various devices/vacuum motors and see if they will hold vacuum. If they do not they have a split diaphragm and will need to be replaced. You can also check the various lines looking for leaks.

You can also have a smoke test performed.

I thought this pic may help I used this to find vac leak s
Suck the air out of power st pump
Bleeding breaks
Etcetera

 

[koda2000]

I thought this pic may help I used this to find vac leak s
Suck the air out of power st pump
Bleeding breaks
Etcetera

View attachment 159220

Yep, a vacuum pump is a handy tool.

 

[BadaBingM3]

Fixed! One of the vacuum lines off the vacuum sphere was melted and broken. Replaced and stowed tubing for better routing. A/C back to normal! Thanks fella's.

 

[donalds]

Good job thanks for the update.

 

[puzzaa]

Would this be the case in the instance that the blower runs at idle but when accelerating (above 2.5k rpm) the blower doesnt blow through vents but returns to normal when cruising?

 

[koda2000]

Would this be the case in the instance that the blower runs at idle but when accelerating (above 2.5k rpm) the blower doesnt blow through vents but returns to normal when cruising?

Yes. Small vacuum leak will do this. Our first Explorer did this and I found a PO had plugged an unused port in a rubber t-fitting with a sheet metal screw. It was just enough if a vacuum leak to cause the air to blow out the defroster vents when climbing a large hill near our house. When you accelerate, or climb a hill, engine vacuum is very low.

 

[puzzaa]

Okay I will take a look. The only leak I know is there is near the washer fluid and coolant tank (on v6 4.0 SOHC). There are small tubes there and I broke one when doing spark plugs. I put a joining straw in there and taped around it but that could be it now that I think about it. I know I know I was kind of in a hurry and redneck fixed it haha. I didnt think it would affect anything because the engine still ran. Anyone know what this tube could be? I know Im not being very descriptive but I can upload a pic if needed.

 

[German Engineer]

Okay I will take a look. The only leak I know is there is near the washer fluid and coolant tank (on v6 4.0 SOHC). There are small tubes there and I broke one when doing spark plugs. I put a joining straw in there and taped around it but that could be it now that I think about it. I know I know I was kind of in a hurry and redneck fixed it haha. I didnt think it would affect anything because the engine still ran. Anyone know what this tube could be? I know Im not being very descriptive but I can upload a pic if needed.

Sounds an awful lot like that's one of those hoses used for whatever vacuum actuated motor or device as part from the air conditioning.
Buy sadly any vacuum leak anywhere affects the entire system and can cause weird symptoms elsewhere.

Just fix that hose properly and see.
You're actually lucky to be fairly certain that this improvised hose fix is most likely your problem. Checking vacuum hoses for leaks giving your car a "********" with smoke (from a professional machine or with cigars) can be a REALLY frustrating endeavor.