Hey there and thanks for replying.Probably a vac line or maybe a washer fluid hose, see if you can find where the other end goes.
A few guesses might include the vac reservoir ball around the glove compartment or the heater control valve. I don't recall if the fuel rail dampener hose is that small but if so, another thing to check.
Which engine?
Have you noticed any functional problems like the HVAC blowing out the wrong vents (when not set to defrost), or only doing it under heavy throttle, or not being able to toggle from cold to hot air, or a rough idle, or any check engine light / codes set? I'd assume it's running a bit lean if that's a vac line.
You might also search this forum for related topics. Here's one but I'm sure there are more:
Heater Control valve vacuum line?
Welp; I've had my '03 Explorer Sport for a week now, and with a little work, I've got it running better. I've come to the conclusion, that someone disconnected the climate control and heater control valve vaccum lines on the left side of the engine compartment, and didn't get them back together...www.explorerforum.com
Ok thanks for the help. I will try to trace it back the best I can and report back.Okay so probably HVAC related. I would just keep looking around or check the black plastic ball vac reservoir (might be mounted to the right wheel well liner? IDK on an '02), or the vac line going to the water diverter valve on the heater core hose, I mean follow that line till you see a Tee with a few lines and if your hose didn't come off that tee, follow the hoses on that Tee to see where the next Tee is. Keep following them all the way to the intake... or vice-versa, find all the little lines on the intake and trace them the other direction... or wait for someone with an '02 4.0L to see this topic.
Since the line is coming off, probably needs a nylon or steel wire tie put on to hold it in place.
If all else fails, you might be able to find the leak (where that hose attaches) doing a smoke test.
More pics. I can't find anywhere this hose attaches too. It seems to be tapped to another vacuum line so it must connect somewhere in that general vicinity.
www.harborfreight.com
I can't make out much from the pictures, am more of a hands-on follow the hose type person...
You have the two vac lines going through (coming out) the firewall. One of them should go to the water valve on the hose to the heater core, so I would try to follow the hose connected to that heater core valve and look for a Tee on it.
The other hose coming out the firewall should go to a check valve connected by another piece of hose, to the vac reservoir ball, or direct to the vac reservoir ball if the check valve is built in or on the vac reservoir ball.
The other way to try to figure this out is by symptoms. If it's going to the heater valve, you lose control of switching between hot and cold, would have lack of vac on the hose to the heater valve for both hot and cold, dash settings, while normally one or the other dash setting (hot vs cold) would cause vac on the heater core valve.
You can do a smoke test inexpensively with a dollar cigar and a transfer pump. You have to block the snorkel connecting to the air filter box so the smoke can't escape there.
Multi-Use Transfer Pump
Amazing deals on this Multi-Use Transfer Pump at Harbor Freight. Quality tools & low prices.
There's a better video somewhere on youtube but I can't find it right now. You can make a cap like the guy in the video did to connect to the intake snorkel, or just block it off (plastic bag over it and a rubber band to hold it will work) and pick a different entry point for the smoke like the brake booster hose or elsewhere, so you need no additional parts besides the transfer pump and what comes with it. Transfer pump is also sold on ebay, amazon, etc at higher price.
I can't make out much from the pictures, am more of a hands-on follow the hose type person...
You have the two vac lines going through (coming out) the firewall. One of them should go to the water valve on the hose to the heater core, so I would try to follow the hose connected to that heater core valve and look for a Tee on it.
The other hose coming out the firewall should go to a check valve connected by another piece of hose, to the vac reservoir ball, or direct to the vac reservoir ball if the check valve is built in or on the vac reservoir ball.
The other way to try to figure this out is by symptoms. If it's going to the heater valve, you lose control of switching between hot and cold, would have lack of vac on the hose to the heater valve for both hot and cold, dash settings, while normally one or the other dash setting (hot vs cold) would cause vac on the heater core valve.
You can do a smoke test inexpensively with a dollar cigar and a transfer pump. You have to block the snorkel connecting to the air filter box so the smoke can't escape there.
Multi-Use Transfer Pump
Amazing deals on this Multi-Use Transfer Pump at Harbor Freight. Quality tools & low prices.
There's a better video somewhere on youtube but I can't find it right now. You can make a cap like the guy in the video did to connect to the intake snorkel, or just block it off (plastic bag over it and a rubber band to hold it will work) and pick a different entry point for the smoke like the brake booster hose or elsewhere, so you need no additional parts besides the transfer pump and what comes with it. Transfer pump is also sold on ebay, amazon, etc at higher price.
I will check out later and report back. Thanks
Wait.......I missed the part where you mentioned the Explorer is a 2002.
I lucked out and found a you tube video! You were correct it connects to the Heater control Valve. I could never see it because it was located right under the intake hose.
Thanks for the invite. join request already sent
