I have read all of the threads for this problem and everyone agrees that if your AC blows cold air from the defroster, it is a vacuum leak. I have looked at all of the vacuum connection, back of the EATC, intake manifold, yellow tube to the silver heater motor, 1/8" hard line going into the firewall passenger side and I STILL cannot find the problem. It only happens when the car is under load and moving, not while idling. Is there a way I can FORCE the vents to stay on instead of having it switch over to the defroster? I live in Arizona and defrosters are not important here. Any help is appreciated.
AC blowing through defroster vents
- Thread starter ruswin
- Start date
kustomizingkid
Dedicated LVC Member
How have you tried to find the vacum leak?
bryantaylor
Dedicated LVC Member
what year car? if its a gen 1 the vac line goes to the center of the intake mani
It is a 94. I have visually looked over all of the connections. I checked all of the lines for cracks and holes, can't find any. Is there someway I can isolate the problem? Besides doing that, I guess I could just start replacing lines?
driller
Dedicated LVC Member
Try replacing the check valve.
You will have normal vacuum when idling and low vacuum when under load and moving(accelerating). With a faulty check valve, you could be loosing vacuum to the EATC. The check valve isolates the EATC vacuum from the fluctuating intake manifold vacuum.
Your explanation of why it is happening only under power, makes sense. I was thinking backwards on that one. For some reason I was thinking that the vacuum would increase as the engine is under load, not the opposite. Guess I never hooked up a vacuum gauge to see that.
Stupid question #2... where is the check valve? I see there is a check valve on the passenger side firewall that has the 1/8" line coming from the manifold, and then (2) 1/8" lines on the other side. Is that it? One of the 2 lines disappear through the firewall, the other goes into the wheel well and then goes forward towards the grille. The 1/8" line that goes forward towards the front of the car is the only one I did not inspect yet. (It will probably turn out to be the problem knowing my luck) I will just try to isolate it by disconnecting it and capping the port.
Stupid question #2... where is the check valve? I see there is a check valve on the passenger side firewall that has the 1/8" line coming from the manifold, and then (2) 1/8" lines on the other side. Is that it? One of the 2 lines disappear through the firewall, the other goes into the wheel well and then goes forward towards the grille. The 1/8" line that goes forward towards the front of the car is the only one I did not inspect yet. (It will probably turn out to be the problem knowing my luck) I will just try to isolate it by disconnecting it and capping the port.
driller
Dedicated LVC Member
Hmm... I'm not sure 'bout the one at the firewall. I know what you're talking about as it's the same on my '96. On my '93, the check valve is among the vacuum line bundle at the drivers side of the intake manifold sort of beside/behind the IMRC and EGR solenoids. It is cylindrical and one half of it is blue.
Also check the vacuum line going to the evap emission device. It's a larger vacuum line coming of the throttle body, running along the cowl and then to the fenderwell area. I had that line develop a leak once.
Also check the vacuum line going to the evap emission device. It's a larger vacuum line coming of the throttle body, running along the cowl and then to the fenderwell area. I had that line develop a leak once.
OK, I checked the check valve you mentioned and still cannot find the leak. If I replace the line that enters the cabin through the firewall, will that "bypass" the problem? Either that or is there someway to just over ride the vent selector and lock it into the vents. Being in Arizona, it will be 100'+ for the next 4 months, I do not need the defroster. I understand hat the default is to have the air blow out the defrost, how do I lock that out?
driller
Dedicated LVC Member
I would get a vacuum gauge and splice into the line going to the EATC and see what the vacuum does when you drive it. If it drops - it's a bad check valve. Maybe the little vacuum resevoir has a leak? Looks like that 2 into 1 fitting by the firewall is the checkvalve we need to investigate.
As far as over-riding the vent/defrost actuators, I suppose you could but they are a PITA to get to. It would likely be easier to fix the vacuum problem.
As far as over-riding the vent/defrost actuators, I suppose you could but they are a PITA to get to. It would likely be easier to fix the vacuum problem.
AbrahamLincoln
Dedicated LVC Member
intake manifold vac line that runs into the passenger side fender to the vac canistor is severed, if its leaking it will only come out of the vents. follow the line from the vac cansister in the pass. fender and you'll find your leak - mine broke right at the canister so you'll probably just discover that as well.
get the right fitting to just bypass the vac canister so the vac line on top of the intake manifold plugs right into the HVAC line coming out of the firewall.
the only bad part is you're fan will decrease at full throttle (high vac)
get the right fitting to just bypass the vac canister so the vac line on top of the intake manifold plugs right into the HVAC line coming out of the firewall.
the only bad part is you're fan will decrease at full throttle (high vac)
It sounds like the vacuum canister or line to it might be the problem. I did try to just cap that connection off and test it without the canister connected, and the problem stayed the same, so I figured it would not be a problem with that line. But if the vacuum canister serves an important function to buffer the vacuum and keep it at a steady level, then I need to check it. What is the best way to get to it?
Located behind passenger side fender liner, top left when looking in.
Edit: Look at 3rd pic in this thread. (dangling down in front of door hinge area - yours will be bolted up)
http://www.lincolnvscadillac.com/showthread.php?t=34515&highlight=rust
I pulled the vacuum canister out and looked at it, cannot find any leaks. I traced the black tubing coming through the firewall behind the glovebox, it looks like it enters a tubing connector with another 3 colored tubes, it also appears to be sealing OK. I looked at the back of the EATC and the connections there also look OK although the rubbery connector is a little loose, it still seems to be sealing.
1) Is it possible that the EATC has an internal leak? I ran the EATC dignostic and came up reading 888 which is supposed to mean it is OK, I don't know if it can detect an internal leak though?
2) Can I run a new line from the check valve on the firewall directly to the back of the EATC?
3) I assume that black line connects from the check valve to the FCCB connection on the back of the EATC?
4) Would the throttle body fitting and / or the PCV valve have anything to do with it? To this point I have only been looking at the intake manifold vacuum connection that tees off to the brake booster and the firewall check valve.
This is really frustrating!
1) Is it possible that the EATC has an internal leak? I ran the EATC dignostic and came up reading 888 which is supposed to mean it is OK, I don't know if it can detect an internal leak though?
2) Can I run a new line from the check valve on the firewall directly to the back of the EATC?
3) I assume that black line connects from the check valve to the FCCB connection on the back of the EATC?
4) Would the throttle body fitting and / or the PCV valve have anything to do with it? To this point I have only been looking at the intake manifold vacuum connection that tees off to the brake booster and the firewall check valve.
This is really frustrating!
Driller... your vac diagram pointed me in the right direction. I isolated the problem by making a short jumper tube and connected it on the tubing connector after removing it from the back of the EATC. Jumping from the black to the yellow which controls the vent door will keep the VENTS on no matter what. (As long as you do not have another vacuum leak somewhere) When the EATC is jumped out, the AC blows perfectly from the vents. So there must be an internal leak inside the EATC itself. I can see that there are 4 solenoids inside it that are responsible to change the functions. When I blow into them, I can hear air leaking through them. So I am on my way to the junkyard to try to find a 93-96 EATC from a Continental, Mark 8 or SHO. Once I have it installed I will close this thread with good news. (I hope) At least for now with the vac lines jumped together, I have cold air blowing at me instead of from the defrost. Thanks for all the help, I am sure this will help someone in the future. Still trying to figure out the problem with my ABS light on another thread I have going... always something!
Duck
Well-Known LVC Member
Good Luck
Mine is doing the same thing. Today I ran new line to valve and to the canister, still air does not come out the vents. All other buttons switch to the correct location, except the vent?
It is driving e crazy!!!!!!!!!!!!!!!!!!
Mine is doing the same thing. Today I ran new line to valve and to the canister, still air does not come out the vents. All other buttons switch to the correct location, except the vent?
It is driving e crazy!!!!!!!!!!!!!!!!!!
driller
Dedicated LVC Member
1) I guess it is possible to have an internal leak of the EATC. The self test only checks for electrical faults.
2) Yes.
3) Yes.
4) Yes, any vacuum leak will cause even lower vacuum when accelerating.
You effectively put the panel door vacuum motor to the Max AC position.
You can see from the diagram, when the EATC is in Defrost mode, there is no vacuum to any vacuum actuators. Makes me wonder if one of the other vacuum motors may be leaking?
GMAN
Dedicated LVC Member
I had this very same problem with my 93 two years ago.
Clicky Clicky
Clicky Clicky
Duck
Well-Known LVC Member
I had this very same problem with my 93 two years ago.
Clicky Clicky
Yes, but I ran all new tubing from that port.......still no workey.
GMAN
Dedicated LVC Member
Yes, but I ran all new tubing from that port.......still no workey.
You know, it is highly possible that the vacuum lines behind the EATC could be loose or out. One of the lines must have come loose. When I did my dash swap on my 93 three years ago, I accidentally pulled one of those lines, I believe it was the red or the yellow one out. I had to loosen every thing and pull the dash back out trace everything. The yellow line goes to some type of canister that is way in back. I was friggin nightmare.
Duck
Well-Known LVC Member
That may be it, because today I ran a hose direct from the port on the engine, to the line going in the firewall to the EATC and still no air through the dash vents, defrost yes.
Duck
Well-Known LVC Member
I would get a vacuum gauge and splice into the line going to the EATC and see what the vacuum does when you drive it. If it drops - it's a bad check valve. Maybe the little vacuum resevoir has a leak? Looks like that 2 into 1 fitting by the firewall is the checkvalve we need to investigate.
As far as over-riding the vent/defrost actuators, I suppose you could but they are a PITA to get to. It would likely be easier to fix the vacuum problem.
Driller,
what year is this diagram for? The book for my 93 shows the yellow and blue to be the opposite from this one.
driller
Dedicated LVC Member
Really? That diagram should be for my '93 - right out of the EVTM? I'd have to check the hardcopy I have but that pic was from the DVD manual.