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I have a workhorse 2001 E350 15-passenger van for my motorcycle tour company. I keep it in good shape, which is difficult in the Caribbean.
Recently when going up steep grades, the a/c diverts to the defroster. When vacuum is reduced it goes back to normal on the dash.
I had this same problem in my 2010 Explorer, and the problem was a clogged vacuum check valve, easy to fix. So I thought that was the same problem with the van.
So I pop open the hood and found this:
A disconnected vacuum line with nothing close that plugs in.
Then I poke around some more and find this under the hood on the other side of the engine:
What appears to be a vacuum source with nothing connected.
Am I missing a vacuum line? This would be an easy fix if the line is missing. If so, is there supposed to ba a check valve or something in this line?
Or am I missing something?
Thanks for your help, it is gratefully appreciated.
The line you're holding should be connected to a hard plastic red colored line running from the throttle body. The line in your hand goes to the HVAC system reservoir and check valve. Here's an annotated photo that might help:
That image ^^^ is a modification from the factory I devised in order to bypass the stock vacuum reservoir and check valve which are both mounted in an impossible to find and service location. As shown I simply disconnected and abandoned the factory line in favor of my own fix.
The device in your other photo might be the fuel pressure regulator---I'm assuming that view is on the left/drivers side as seen from the back of the engine? If its missing its vacuum signal your fuel pressure could be affected.
The line you're holding should be connected to a hard plastic red colored line running from the throttle body. The line in your hand goes to the HVAC system reservoir and check valve. Here's an annotated photo that might help:
That image ^^^ is a modification from the factory I devised in order to bypass the stock vacuum reservoir and check valve which are both mounted in an impossible to find and service location. As shown I simply disconnected and abandoned the factory line in favor of my own fix.
The device in your other photo might be the fuel pressure regulator---I'm assuming that view is on the left/drivers side as seen from the back of the engine? If its missing its vacuum signal your fuel pressure could be affected.
I don't find a hard red line from the throttle body.
Is that line I'm holding in my hand the reason the a/c diverts to the defrost under high manifold pressure, like going uphill? It's not connected to any vacuum?
As far as the pressure regulator, I don't see any vacuum lines anywhere near it.
I don't find a hard red line from the throttle body.
Is that line I'm holding in my hand the reason the a/c diverts to the defrost under high manifold pressure, like going uphill? It's not connected to any vacuum?
As far as the pressure regulator, I don't see any vacuum lines anywhere near it.
Yes on the A/C vents diverting during reduced vacuum---defrost is the default air flow should the HVAC system lose all vacuum. If you're able to currently switch air flow from Vents to floor or the Mix setting then some vacuum from somewhere is present.
I posted two threads on the venting system that might help you diagnosing your issues: Van Air Flow System 1. It might be a bit more detailed than you need or want but it could be useful.
Yes on the A/C vents diverting during reduced vacuum---defrost is the default air flow should the HVAC system lose all vacuum. If you're able to currently switch air flow from Vents to floor or the Mix setting then some vacuum from somewhere is present.
I posted two threads on the venting system that might help you diagnosing your issues: Van Air Flow System 1. It might be a bit more detailed than you need or want but it could be useful.
At idle and under low load, the vent system works fine. I can change the **** to various outlets with no problem.
It is only under a heavy load, like up a steep grade, when the air goes to defrost.
Thanks for the link, very helpful. I just don't see any line to the throttle body for vacuum to connect to the line in my hand.
At idle and under low load, the vent system works fine. I can change the **** to various outlets with no problem.
It is only under a heavy load, like up a steep grade, when the air goes to defrost.
Thanks for the link, very helpful. I just don't see any line to the throttle body for vacuum to connect to the line in my hand.
So you do have vacuum to the HVAC system otherwise none of the functions would work apart from defrost.
The factory vacuum line connecting to your in-hand piece would be a red hard plastic tube running out of the side of the throttle body towards the passenger side of the engine bay. It would turn towards the front and emerge near the oil fill tube. The photo I posted shows that line marked as "from intake"---if that's not there I'm not sure how someone routed vacuum to your system. Regardless there will be some sort of hose or tubing connected to the throttle body as that's the best source.
Once you find a vacuum source my linked post should help you correct your uncommanded vent switching issues.
Sorry I can't be more helpful but you have a modified van I'd need to see in person to better determine how to proceed.
With the engine running, see if there is vacuum present on the unattached line. If so, stop it up. Been there with numerous Ford vehicles. It can be very aggravating keeping that vacuum system leak-free. At least on most vans, the vacuum operator is at the top underneath the easily removable plate, as seen in JWA's link.
The defrost/vents vacuum operator #2 has a spring pushing a diaphragm that keeps the operator in defrost with low or no vacuum. Moving to the dash vents position requires constant vacuum to overcome that spring. It has a single vacuum line. The mixer operator has two vacuum lines. Picture stolen from JWA's link.
I have resorted to using a nylon tie-wrap or piece of wire, wrapped around Vac Sol #2 attachment stud/screw and the white arm to force the actuator to the vents position to get by until finding the vacuum leak. Tying it in between allows both defrost and vent. In hot weather, I've gone heavier on the dash vents. Fan on high helps clear windshield fog.
Don't try this at home. I'm not responsible for damage to the white arm, although I never have. I've also never tried removing the two mounting screws and moving the vacuum solenoid to the left.
It does make you appreciate the AC more when waiting to crest the long grade for that blast of cold air in the face.
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