HVAC Issues. Also, trailer towing question.

First, the HVAC issues. There is a distinct vacuum leak from somewhere under the passenger side dash. I'm guessing that's causing my problem but I'm unsure what part to be looking for.

If I have the AC on set to anything other than defrost occasionally the air flow stops coming from the vents and only comes out of the defrost vents. It seems to typically happen under load although it has been getting worse and doing the same thing while at a constant RPM on the highway. Any ideas on what the issue is or where to look?

Also, I'm looking at a move from PA to TX this summer. Truck just turned 179k. I'm considering getting one of the small U-Haul trailers to tow with me for the final drive down there with the last of my stuff. I've never towed anything with this. What do I need to know and do to prepare for the drive? It has a towing package I believe as there is a hitch and a harness.

I used my 03 XLT 4.6 V8 Explorer with towing package to move almost all of my possessions from CO to TX. I was using both houses for some time so I made multiple trips pulling a relatively small 12 ft covered trailer.
My X had about the same mileage as yours, performed admirably, and had no failures on any of the 10 or so trips I made over about a year's time.
Other than the obvious good tires, brakes, engine oil, coolant, belts, hoses, tune-up, you shouldn't need anything, but you should consider the following:
1) Transmission is the weak link. With the Ford towing package you should already have a transmission cooler, this is absolutely necessary in my opinion.
2) Get the trans fluid changed, however, if you've never changed the fluid before, you should reconsider this advice (there are many posts on this forum discussing this issue).
3) Put new brake pads on the front brakes, and change your rotors to good quality slotted rotors.
4) Change the rear differential oil if you haven't done it in more than 50K miles.
5) Check the U-joints in both drive-shafts. These are pretty tough and should be fine if you don't tow much, but it's easy to check.
6) My trips also gave me the excuse to add an aftermarket cat-back exhaust. This is probably not necessary, but it made me feel better with the engine running over 3K RPM for hour-long periods. You could also just slow down.
7) Carry a spare tire for the trailer, and a jack that will work on the trailer.
8) Make sure you have emergency breakdown assistance that covers the trailer just in case you do have a failure on the road. Again, make sure the towing service you have covers the trailer, you don't want to have to leave the trailer with your stuff behind if you need a tow.

That's all I can think of, good luck and have fun.

Thanks Lane.

I've had the transmission fluid changed before but it's been close to 50,000 miles or so. Same with the rear differential; it was rebuilt right at 40,000 miles ago. I'll probably get both of those done in the near future.

New tires in Feb of this year, new pads and rotors on all four wheels within the last month, new water pump (which means flushing and refilling of coolant) about three months ago along with a new belt ... Think I'm good to go on that kind of stuff.

Note Uhaul won't let you tow their trailers with an Explorer unless its like a 2010 or newer.

Why?

You have a hose off somewhere on your hvac. I found the one under the hood that controls the heater core flow to be off of mine. It was doing as you described, under accel I wouldn't have enough vacuum to hold the door open for the vent. Also if I would turn it to recirculate It would lose enough of a vacuum that my air would stop coming out of my vents. The hose I found was under the hood under the air intake tube. There's an actuator there that controls the water flow thru the heater core. It was just hanging there. I would check all your lines, if one is off you will not have enough vac to hold the actuator that controls the vent door open.

dieselscout80 said:

Note Uhaul won't let you tow their trailers with an Explorer unless its like a 2010 or newer.

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Yup, they told me the same thing. Something about tire recalls and roll-over issues. Trying to explain to the kid behind the counter that the recalls never affected 2002 and beyond models seemed useless. I moved on....

What's really hilarious, is that their rates board that has silohettes of vehicles towing trailers, had one of an Explorer for the longest time.

You can get a UHaul trailer with your Explorer, just don't go to an actual UHaul place. Go to a gas station that also rents uhauls.

roush9799 said:

You have a hose off somewhere on your hvac.

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+1 You have a vacuum leak. There can be lots of causes. Besides the one mention. In my case I had bad vacuum control valve. Under the hood, part number YG360. Less than 5 minute fix for me. Also check under the dash/glovebox for leaks in/out of the vacuum reservoir.

icepickjazz said:

+1 You have a vacuum leak. There can be lots of causes. Besides the one mention. In my case I had bad vacuum control valve. Under the hood, part number YG360. Less than 5 minute fix for me. Also check under the dash/glovebox for leaks in/out of the vacuum reservoir.

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Reading through the reviews for that part on Amazon I have a similar "hiss under the dash" as one reviewer. Where is this part located on the vehicle?


#21 here?

I had two hoses that fell off the actuators on mine. One was under the hood on the one that controls the coolant flow to the heater core, the other was the white hose behind the glove box where it connects to the actuator. It plugs on to the bottom, I think it finally over the years worked loose and fell off. When I put the a/c on to recirculate, I would lose enough vacuum through that line that it would cause the door to the vents to shut and the air would come out the defrost.

BigFellor said:

Reading through the reviews for that part on Amazon I have a similar "hiss under the dash" as one reviewer. Where is this part located on the vehicle?


[URL=http://www.explorerforum.com/forums/usertag.php?do=list&action=hash&hash=21]#21 here?[/URL]

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Yeah, it's #21 and it's located under the hood, passenger side near the firewall where the vacuum lines exit the firewall. Here's a pic from a 2008. On my 2004 the part was located much further towards the passenger fender and would have been out of frame on this photo, but it gives you the general idea.

Thanks. At least i know what I'm looking for now.

Success!

Found the vacuum leak pretty quickly thanks to the help from you guys. The check valve under the hood was bad and was allowing air both ways. While replacing that I also found the hard hose from that valve into the firewall was broken off inside the housing. I managed to get that out and kind of jerry rig it up by placing some larger vacuum line over the fitting sticking out of the firewall. Air stays on the vents now instead of coming out the defroster.

Got the valve at a local stealership for $15. Could have gotten it online cheaper, but wanted to try it out and get this done.

Uhaul will rent to you with a mercury mountaineer. Mountaineer tails are cheap....


for what it's worth... If you pick it up with a not explorer, and drop it off after hours with your explorer when you get there, and don't mention the explorer at all, you're fine.