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

[Turdle]

Is this behind the AC controls in the dash? Gotta take out radio bezel and then pull ac controller?

H ( heat) V (vent) AC ( air conditioning)

Yes, on the back of the HVAC control. However, you need to repair your gray line, as it is leaking vacuum which prevents the system from working properly.

 

[Kanyne]

I know I'm reviving a dead thread, but I'm new to the forum. This thread has been hugely helpful to my understanding! I have a new-to-me 2001 Sport Trac 4WD with a 4.0 SOHC. It has the same issue with defrost-only HVAC as many others. I have found 3 (at least, up to this point) disconnected vacuum lines hanging loose in the engine compartment.
#1 - Black line coming from the firewall. A rubber connector is on the hose around 2 feet past the firewall. Where does this connect?
#2 - A White/Gray line coming from the firewall. A rubber connector is on the hose just a little longer than the black line. I understand this is a supply line, but from what?
#3 - A Red line coming from the EGR system. This one wraps around the back of the intake and is laying disconnected along the top of the engine. Some genius put a screw in it to plug it, rather than fix the issue.
*Note: I have found an open vacuum hose connection on a cylinder sitting below the alternator. The body looks like a smaller version of the vent door actuators inside the dash. What line connects here and what does it do?
**Also, I found a black line running along the top of the frame rail front to back that goes to something near the brakes. I assume the other end goes to the vacuum reservoir, but I'm going to check that out soon.

Also, what are the two lines from the vacuum reservoir connected to? I guess a hand-holding walkthrough of the vehicle's outside vacuum hose layout would be great. The engine was replaced before I got it, and I suspect the vacuum lines were reconnected shoddy.

 

[Turdle]

I know I'm reviving a dead thread, but I'm new to the forum. This thread has been hugely helpful to my understanding! I have a new-to-me 2001 Sport Trac 4WD with a 4.0 SOHC. It has the same issue with defrost-only HVAC as many others. I have found 3 (at least, up to this point) disconnected vacuum lines hanging loose in the engine compartment.
#1 - Black line coming from the firewall. A rubber connector is on the hose around 2 feet past the firewall. Where does this connect?
#2 - A White/Gray line coming from the firewall. A rubber connector is on the hose just a little longer than the black line. I understand this is a supply line, but from what?
#3 - A Red line coming from the EGR system. This one wraps around the back of the intake and is laying disconnected along the top of the engine. Some genius put a screw in it to plug it, rather than fix the issue.
*Note: I have found an open vacuum hose connection on a cylinder sitting below the alternator. The body looks like a smaller version of the vent door actuators inside the dash. What line connects here and what does it do?
**Also, I found a black line running along the top of the frame rail front to back that goes to something near the brakes. I assume the other end goes to the vacuum reservoir, but I'm going to check that out soon.

Also, what are the two lines from the vacuum reservoir connected to? I guess a hand-holding walkthrough of the vehicle's outside vacuum hose layout would be great. The engine was replaced before I got it, and I suspect the vacuum lines were reconnected shoddy.

#1 connects to a line from the reservoir
#2 should be grey and runs to the vacuum bypass valve in the heater core supply hose
#3 red line goes to the fuel pressure regulator. Green to egr vacuum solenoid

The black lines running along the fenders-engine front to rear are the vacuum source and reservoir lines. there will be 2 back lines attached to the reservoir.

 

[Kanyne]

#1 connects to a line from the reservoir
#2 should be grey and runs to the vacuum bypass valve in the heater core supply hose
#3 red line goes to the fuel pressure regulator. Green to egr vacuum solenoid

The black lines running along the fenders-engine front to rear are the vacuum source and reservoir lines. there will be 2 back lines attached to the reservoir.

Thanks so much, Turdle. I assume by "fuel pressure regulator," you are talking about the small canister sitting below the alternator? Or is it something else?

 

[Kanyne]

Well, I just jacked up the truck and found that the black line running on the frame rail is actually power. The vacuum reservoir has been removed, so there is no supply line. So, now I wonder where the source of the black supply line is in the engine? Until I get another reservoir, I can patch into that, maybe, and get suction from the right source.

By the way, I found the vacuum supply line and patched the gray into that. No issues. But, I found what looks like the FPR on the back of the fuel rail on the passenger side, but I can't find a vacuum port. The only thing I see is the screw-on cap, but that is the pressure relief valve, right? What am I missing?

 

[Turdle]

Well, I just jacked up the truck and found that the black line running on the frame rail is actually power. The vacuum reservoir has been removed, so there is no supply line. So, now I wonder where the source of the black supply line is in the engine? Until I get another reservoir, I can patch into that, maybe, and get suction from the right source.

By the way, I found the vacuum supply line and patched the gray into that. No issues. But, I found what looks like the FPR on the back of the fuel rail on the passenger side, but I can't find a vacuum port. The only thing I see is the screw-on cap, but that is the pressure relief valve, right? What am I missing?

I think that is the fuel pressure test port. There should be a "pressure damper" with obvious diaphragm shape on the fuel rail also.

 

[Kanyne]

Thanks. I'll check for that. Hooked up the red line to the black line, and at least I have A/C right now. But I still need to route the black line back to its source. Anyone know where that hookup is (before the vacuum reservoir)?

 

[Billy260Z]

I must have a leak in the defrost vent ? because my explorer blows a/c thru the vents but the wind shield get foggy . I checked the vacuum lines before . but my globe is next the overflow tank.

 

[239]

Mine decided to start switching back and forth between defrost and max ac when I’m driving. Time to go leak hunting this weekend. It doesn’t help that it’s in the mid 80’s during December here in Florida and I need my ac to work correctly But hey, we have a “cold” front this weekend with highs in the 70’s so it’ll be a little more pleasant to work outside

 

[CDW6212R]

Mine decided to start switching back and forth between defrost and max ac when I’m driving. Time to go leak hunting this weekend. It doesn’t help that it’s in the mid 80’s during December here in Florida and I need my ac to work correctly But hey, we have a “cold” front this weekend with highs in the 70’s so it’ll be a little more pleasant to work outside

Oh, shut up. We're hitting below freezing this week, with highs in the low 40's a couple of days. The people up in the real north have snow on the ground now and I don't envy them either. Have fun there in the heat.

I feel for you because my 98 Mountaineer still has the hot MAX AC problem, the blend door I'm sure. I'm happy I've got heat in the mornings and AC when we do hit the 60* mark occasionally. I've got a leaking roof that I haven't tracked down yet. I sealed the sunroof with RTV, and it still drips just as much. I'm tired of getting wet inside the car. I think the rubber sealing edge might have separated from the glass, it's about all that's left for water to get in and drip from the front corners of the sunroof opening.

 

[239]

Oh, shut up. We're hitting below freezing this week, with highs in the low 40's a couple of days. The people up in the real north have snow on the ground now and I don't envy them either. Have fun there in the heat.

I feel for you because my 98 Mountaineer still has the hot MAX AC problem, the blend door I'm sure. I'm happy I've got heat in the mornings and AC when we do hit the 60* mark occasionally. I've got a leaking roof that I haven't tracked down yet. I sealed the sunroof with RTV, and it still drips just as much. I'm tired of getting wet inside the car. I think the rubber sealing edge might have separated from the glass, it's about all that's left for water to get in and drip from the front corners of the sunroof opening.

Hey, I’m just hoping that the heat will drive some of the snowbirds and tourists away, so traffic isn’t as bad I always wanted a sunroof, but leaks like yours lessen that desire. Good luck sealing that leak, I hope I can find the issue soon as we’ll be back in the 90’s come spring

 

[CDW6212R]

I love the Fall and Spring, temps between too hot and too cold, 50-70 is my favorite range.

 

[stakreutemazda]

Please feel free to add info or discuss this problem--

Ok, the red blue and yellow line go to no mans land-let's forget them right now.

The white "controlled vacuum" line (from HVAC switch) now goes back through the bulk connector, to the glove box area,through several connections and "T's" to the defrost baffle "motor" (diaphragm)-and back through the firewall for controlled vacuum to the Grey coolant bypass valve line.
Phew!

My question is the white vacuum line,controlled vacuum line. It "t"s to the defrost baffle motor as well as a feed to the gray tube at the HCV. When I select the proper function on the dash switch the vac goes on? Does it operate both vacuum operated diaphragms? I was thinking that a selector on the switch activates vac at each diaphragm. Does the control go up or down at the unit under the dash? How is the HCV affected? which way controls the water flow through the heater core.Thank you

 

[Turdle]

I think vacuum is always present at the white line. Vacuum is switched to the grey line when cold temp is selected. does this help?

edit. if you have an EATC control unit, there are well known vacuum issues associated to it not covered in this thread. Usually it requires a very tedious rebuild, or, replacement.

 

[CDW6212R]

I appreciate any explanation details. I've got to R&R my 98 AC dash unit, and also figure out how the main system functions work. I hope to install the same EATC control head into my old 92 Lincoln. I'm hoping the functions are compatible, I really don't like the older Ford EATC dash controls.

 

[stakreutemazda]

I think vacuum is always present at the white line. Vacuum is switched to the grey line when cold temp is selected. does this help?

edit. if you have an EATC control unit, there are well known vacuum issues associated to it not covered in this thread. Usually it requires a very tedious rebuild, or, replacement.

I need for us to be on same page. A black tube is the vacuum source from a manifold source, to the vac ball and on to the firewall then through cab to control switch. the white tube comes from the switch, through the cab to a air recirculate valve/diaphragm that operates a door to outside air. It's here that a gray tube continues through the firewall to the HCV on a heater hose. My confusion starts here. The white tube supplies two diaphragms on two units, one inside and a gray tube goes through firewall to the HCV. The HCV operates on max a/c or the off position on heater control? Not sure which color tube operates the heater functions? but I'm guessing the black?FYI I have a b2500 Mazda with 2.5L. I followed your post for the Explorer, very close to exactly the same but I've backed myself into a corner?

 

[239]

I appreciate any explanation details. I've got to R&R my 98 AC dash unit, and also figure out how the main system functions work. I hope to install the same EATC control head into my old 92 Lincoln. I'm hoping the functions are compatible, I really don't like the older Ford EATC dash controls.

I’m still dreaming of adding EATC to my 2000 someday, but it looks like I won’t have auto ac until I buy a new ranger.

 

[CDW6212R]

I’m still dreaming of adding EATC to my 2000 someday, but it looks like I won’t have auto ac until I buy a new ranger.

You can do that with little trouble, Eric made a thread about 7+ years back, doing his 99 Explorer Sport(302 and Mountaineer front end). It's been done a few times, that thread is the best one I recall describing it.

 

[239]

You can do that with little trouble, Eric made a thread about 7+ years back, doing his 99 Explorer Sport(302 and Mountaineer front end). It's been done a few times, that thread is the best one I recall describing it.

I’ve looked for threads online but the pictures are usually missing and there aren’t any wiring diagrams.

 

[CDW6212R]

I’ve looked for threads online but the pictures are usually missing and there aren’t any wiring diagrams.

Eric is still on here sometimes, he's got an LS engine in one now. Let me hunt a little for it.

Here's Eric's old 302 swap thread(2006), and the pictures all seem to be there. I don't find a thread of his that's just for the EATC. I think he might have described the EATC swap in that V8 swap thread, or his Mountaineer front end swap, instead.

5.0L V8 Swap into 99 Explorer Sport

I'll delete my superfluous posts shortly.