AIR VACUUM LEAK??
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RE: AIR VACUUM LEAK??
Your real problem is the check valve on the black plastic vacuum line going towards the passenger's side fender where the vacuum reservoir is located. You do not have a leak, and you do not have to remove all your A/C components. A '94 EVTM shows a check valve running along the top of the firewall between the center of the car and the passenger's side. It is held in place by the connected hoses and a nylon plastic strip. You are looking for a small disc, (about 1" round) connected to another cylinderical body on a 90 degree angle with a total of 3 vacuum connections - 1 at the circular head, (which is connected to the vacuum source port on the engine) and 2 connections coming out the side (connection closest to the circular part goes to the vacuum tank and the farthest connection goes through the firewall to the A/C control head). The color of this unit is usually black and is very easy to change. Ford uses them in many of their cars with A/C. So, if you cannot find the part at a Lincoln dealer, just use a Ford part. I would assume that a Gen2 vehicle would be the same. The '98 EVTM does not show that part of the car in detail.
Since you are moving the plastic hoses, be very careful, they break easily. The ends will have a rubber adapter on them. Make sure you keep them on the hose and remove them off the check valve. The best way to remove the connections is to pinch the rubber around the valve and twist it until the seal breaks and then the rubber will pull out easily. Don't try to just pull them out. You WILL break the plastic hose or the rubber from the hose. You will be able to feel when the rubber seal is broken from the plastic on the check valve.
Then remove the hose with the adapter. Make sure you know where to replace each hose, it's important to the operation of the A/C controls.
The check valve holds in accumulated vacuum for the A/C system in the vacuum reservoir mounted inside the right front tire housing compartment behind the plastic shroud. That way, when you are at full throttle or close to it, you will not lose the setting of the A/C control vacuum motors. The system automatically defaults to the defrost mode when there is no vacuum to let you know there is something wrong with the vacuum system and also to make sure you can see if vacuum is lost for any reason. But, by saying the A/C settings change when you are accelerating, it is definately the check valve. If it does not change from defrost when you are idling, then there is a leak in the vacuum system.
Your real problem is the check valve on the black plastic vacuum line going towards the passenger's side fender where the vacuum reservoir is located. You do not have a leak, and you do not have to remove all your A/C components. A '94 EVTM shows a check valve running along the top of the firewall between the center of the car and the passenger's side. It is held in place by the connected hoses and a nylon plastic strip. You are looking for a small disc, (about 1" round) connected to another cylinderical body on a 90 degree angle with a total of 3 vacuum connections - 1 at the circular head, (which is connected to the vacuum source port on the engine) and 2 connections coming out the side (connection closest to the circular part goes to the vacuum tank and the farthest connection goes through the firewall to the A/C control head). The color of this unit is usually black and is very easy to change. Ford uses them in many of their cars with A/C. So, if you cannot find the part at a Lincoln dealer, just use a Ford part. I would assume that a Gen2 vehicle would be the same. The '98 EVTM does not show that part of the car in detail.
Since you are moving the plastic hoses, be very careful, they break easily. The ends will have a rubber adapter on them. Make sure you keep them on the hose and remove them off the check valve. The best way to remove the connections is to pinch the rubber around the valve and twist it until the seal breaks and then the rubber will pull out easily. Don't try to just pull them out. You WILL break the plastic hose or the rubber from the hose. You will be able to feel when the rubber seal is broken from the plastic on the check valve.
Then remove the hose with the adapter. Make sure you know where to replace each hose, it's important to the operation of the A/C controls.
The check valve holds in accumulated vacuum for the A/C system in the vacuum reservoir mounted inside the right front tire housing compartment behind the plastic shroud. That way, when you are at full throttle or close to it, you will not lose the setting of the A/C control vacuum motors. The system automatically defaults to the defrost mode when there is no vacuum to let you know there is something wrong with the vacuum system and also to make sure you can see if vacuum is lost for any reason. But, by saying the A/C settings change when you are accelerating, it is definately the check valve. If it does not change from defrost when you are idling, then there is a leak in the vacuum system.
RE: AIR VACUUM LEAK??
I was assuming the info was great since I received it more than once. Only this was great detailed stuff. Problem is I had the check vavle replaced by a local mechanic per instructions and I have the same problem. 80 to 90% of the time it doesn't work correctly. It defaults to defrost. I stopped at the the local ford dealer yesterday and he sniffed around for awhile and didn't find anything. He says he needs it for more diagnosis but the check valve appears to be ok. I'm really confused about the part time working of the system. It defaults only most of the time and others it woks just fine. Not as cold as I would like though. If I put it on floor and vent, it never defaults, and it works fine but never get cold enough. Off to the Lincoln dealer Sunday night for an overnighter and hopefully on Monday they can find something. The new check valve had three copnnectors and the old one had only two -- in and out. I had the old one reinstalled. Had I known it was so easy I would have tried it myself, lol.
Any other clues??
thanks
I was assuming the info was great since I received it more than once. Only this was great detailed stuff. Problem is I had the check vavle replaced by a local mechanic per instructions and I have the same problem. 80 to 90% of the time it doesn't work correctly. It defaults to defrost. I stopped at the the local ford dealer yesterday and he sniffed around for awhile and didn't find anything. He says he needs it for more diagnosis but the check valve appears to be ok. I'm really confused about the part time working of the system. It defaults only most of the time and others it woks just fine. Not as cold as I would like though. If I put it on floor and vent, it never defaults, and it works fine but never get cold enough. Off to the Lincoln dealer Sunday night for an overnighter and hopefully on Monday they can find something. The new check valve had three copnnectors and the old one had only two -- in and out. I had the old one reinstalled. Had I known it was so easy I would have tried it myself, lol.
Any other clues??
thanks
RE: AIR VACUUM LEAK??
All Marks have 3 connections on their check valves. Some Fords have a check valve built into the vacuum reservoirs and those use just 2 connections.
The larger round portion of the check valve on your Mark has a center nipple on it. That connects to the engine vacuum. Air can only move throgh it away from this connection. The other two are actually connected to the other side of the valve or diaphragm. The middle connection or port goes in through the firewall to the heat A/C controller and the outside port connects to the vacuum reservoir.
If you want to test it out yourself, just suck on the nipple that is on the larger round portion or the port that is in the middle of the circle. The air should be drawn in through both of the other two ports. Now, hold your finger over one (most easily the middle) port and suck on the other one. You should not be able to get any air through the valve from the center port that you used before. If you do, the valve is bad. And I'm sure this will be the case.
All Marks have 3 connections on their check valves. Some Fords have a check valve built into the vacuum reservoirs and those use just 2 connections.
The larger round portion of the check valve on your Mark has a center nipple on it. That connects to the engine vacuum. Air can only move throgh it away from this connection. The other two are actually connected to the other side of the valve or diaphragm. The middle connection or port goes in through the firewall to the heat A/C controller and the outside port connects to the vacuum reservoir.
If you want to test it out yourself, just suck on the nipple that is on the larger round portion or the port that is in the middle of the circle. The air should be drawn in through both of the other two ports. Now, hold your finger over one (most easily the middle) port and suck on the other one. You should not be able to get any air through the valve from the center port that you used before. If you do, the valve is bad. And I'm sure this will be the case.
RE: AIR VACUUM LEAK??
Hey John,
The unit on the car originally, or should I say when I started this repair thing, had only an in and out port. The dealer sent over a three port unit and diagram and with the new setup and when I picked it up from the mechanic it still would default to defrost. Also in testing the old unit we did that by sucking on the end and no air would go one direction which we took to mean the valve was ok.
Anything else you can think of---you have been extremely helpful and I appreciate.
Thanks
Barry
Hey John,
The unit on the car originally, or should I say when I started this repair thing, had only an in and out port. The dealer sent over a three port unit and diagram and with the new setup and when I picked it up from the mechanic it still would default to defrost. Also in testing the old unit we did that by sucking on the end and no air would go one direction which we took to mean the valve was ok.
Anything else you can think of---you have been extremely helpful and I appreciate.
Thanks
Barry
1994blkonblk
Registered
RE: AIR VACUUM LEAK??
i had same problem with 01 grand marquis it wound up being
head unit atc.
i had same problem with 01 grand marquis it wound up being
head unit atc.
RE: AIR VACUUM LEAK??
Barry,
The blend door has absolutely nothing to do with the vacuum system except it is controlled by the same ETAC control module. The blend door is electrically operated and monitored electronically by the ETAC control module. So, don't blame your dealer just yet. I have done the blend door replacement on my '98 twice, and maybe they pulled out or broke a small plastic vacuum line when they replaced your blend door. There are some hoses in the general area. Most shops cut a portion of the dash instead of removing it and they also may have pulled it out too much disconnecting a connection as well. I assume you did not have this problem before they replaced the blend door, and have not had an accident to your passenger side front - specifically around or behind the right front wheel. If not, proceed.
Your best bet is to get a vacuum pump and guage from a local auto store. First remove the battery's negative connector. Next, pry on the bottom panel using your fingers (panel with the with the rear defrost switch on it). It should pop out. Then, remove the 2 screws holding the large plastic woodgrain panel which is then removed by pulling it out and up around the radio, ETAC controller, and the gearshift. It has strong springs, just pull. It may help to place the gearshift in different positions, so have the key in off or run. Remove the ETAC controller by removing 4 torx screws and disconnect the 2 electrical connectors. Remove the two end nuts to the vacuum harness connector to release the vacuum lines from the rear of the ETAC controller. You will have to pry the hose connections away from the controller as well. There are four connection ports that are attached to various vacuum motors and one connected to the vacuum source. They are all color coded. Connect each vacuum line up to the pump and pull a vacuum on it. It should hold a 15 psi. allowing for 1 pound of vacuum per minute for leakage. If you find one that doesn't meet specs, that's your problem. Do the center vacuum source port as well. That should take more time to pull the vacuum, but again, it should meet the above specs. If you find a leak, you may have to purchase radio removal tools to get the radio out in order to fix the hose(s). One hose goes around the middle of the heater A/C plenum and is a "feel and replace" connector. One hose goes over to the blower motor area and one motor in the front has 2 hoses connected to it.
As you look into the vacuum connector, start at the very top and go around clockwise. These are the Lincoln numbers:
#1 (12 o'clock position) - Not used.
#3 (2 o'clock position) - Blue, the Heater Air Damper Door.
#6 (5 o'clock position) - Red, Heater Air Damper Door.
#4, (center of connector) - Black, Vacuum Source.
#5 (7 o'clock position) - White, A/C Inlet Duct Door.
#2 (10 o'clock position) - Yellow, the Windshield Defroster Door.
Ports 3 and 6 go to the same vacuum motor, but there are two different connections on it. Make sure that the Blue hose (#3) is connected to the end of the vacuum motor and the Red hose (#6) is connected to a the middle of the motor.
Barry,
The blend door has absolutely nothing to do with the vacuum system except it is controlled by the same ETAC control module. The blend door is electrically operated and monitored electronically by the ETAC control module. So, don't blame your dealer just yet. I have done the blend door replacement on my '98 twice, and maybe they pulled out or broke a small plastic vacuum line when they replaced your blend door. There are some hoses in the general area. Most shops cut a portion of the dash instead of removing it and they also may have pulled it out too much disconnecting a connection as well. I assume you did not have this problem before they replaced the blend door, and have not had an accident to your passenger side front - specifically around or behind the right front wheel. If not, proceed.
Your best bet is to get a vacuum pump and guage from a local auto store. First remove the battery's negative connector. Next, pry on the bottom panel using your fingers (panel with the with the rear defrost switch on it). It should pop out. Then, remove the 2 screws holding the large plastic woodgrain panel which is then removed by pulling it out and up around the radio, ETAC controller, and the gearshift. It has strong springs, just pull. It may help to place the gearshift in different positions, so have the key in off or run. Remove the ETAC controller by removing 4 torx screws and disconnect the 2 electrical connectors. Remove the two end nuts to the vacuum harness connector to release the vacuum lines from the rear of the ETAC controller. You will have to pry the hose connections away from the controller as well. There are four connection ports that are attached to various vacuum motors and one connected to the vacuum source. They are all color coded. Connect each vacuum line up to the pump and pull a vacuum on it. It should hold a 15 psi. allowing for 1 pound of vacuum per minute for leakage. If you find one that doesn't meet specs, that's your problem. Do the center vacuum source port as well. That should take more time to pull the vacuum, but again, it should meet the above specs. If you find a leak, you may have to purchase radio removal tools to get the radio out in order to fix the hose(s). One hose goes around the middle of the heater A/C plenum and is a "feel and replace" connector. One hose goes over to the blower motor area and one motor in the front has 2 hoses connected to it.
As you look into the vacuum connector, start at the very top and go around clockwise. These are the Lincoln numbers:
#1 (12 o'clock position) - Not used.
#3 (2 o'clock position) - Blue, the Heater Air Damper Door.
#6 (5 o'clock position) - Red, Heater Air Damper Door.
#4, (center of connector) - Black, Vacuum Source.
#5 (7 o'clock position) - White, A/C Inlet Duct Door.
#2 (10 o'clock position) - Yellow, the Windshield Defroster Door.
Ports 3 and 6 go to the same vacuum motor, but there are two different connections on it. Make sure that the Blue hose (#3) is connected to the end of the vacuum motor and the Red hose (#6) is connected to a the middle of the motor.
RE: AIR VACUUM LEAK??
After looking at my '98, I was wrong. There is a 2 port check valve in the car. But, if it was checked out as you said, the problem is probably an open or leak in the vacuum line that goes around the front of the plenum and connects at the outside/recirculate vacuum motor, since it takes a real hot day and you pressing down on the accelerator to make the system default to Defrost. Try removing the lower right hand portion of the dash, up where the passenger's feet would go and look for a hose that goes all around the front and make sure it is connected. You may need a mirror to see if it is, but if the dealer pulled the dash too far, this would be the most likely place for the vacuum line to be disconnected. If it is connected, run the engine for about 2 minutes with the heater A/C controller pressed to OFF and then shut the engine off. Turn the key back to run, but don't start the engine. Press the floor button and make sure you hear the vacuum moving around the hoses. Then try another manual button, and then again. You should hear hissing each time you press a button. It should also stop after about 4 seconds each position. If not, your leak is in the car, and not the check valve or the tank. If nothing happens when you first try to change something, the vacuum tank, control head or specific vacuum motor is leaking.
After looking at my '98, I was wrong. There is a 2 port check valve in the car. But, if it was checked out as you said, the problem is probably an open or leak in the vacuum line that goes around the front of the plenum and connects at the outside/recirculate vacuum motor, since it takes a real hot day and you pressing down on the accelerator to make the system default to Defrost. Try removing the lower right hand portion of the dash, up where the passenger's feet would go and look for a hose that goes all around the front and make sure it is connected. You may need a mirror to see if it is, but if the dealer pulled the dash too far, this would be the most likely place for the vacuum line to be disconnected. If it is connected, run the engine for about 2 minutes with the heater A/C controller pressed to OFF and then shut the engine off. Turn the key back to run, but don't start the engine. Press the floor button and make sure you hear the vacuum moving around the hoses. Then try another manual button, and then again. You should hear hissing each time you press a button. It should also stop after about 4 seconds each position. If not, your leak is in the car, and not the check valve or the tank. If nothing happens when you first try to change something, the vacuum tank, control head or specific vacuum motor is leaking.
Frankie X
Registered
RE: AIR VACUUM LEAK??
Hey, Barry!
It's been a couple of weeks of summer heat. I'm really curious as to whether you got around to fixing the default.
Mr John said:
"But, if it was checked out as you said, the problem is probably an open or leak in the vacuum line that goes around the front of the plenum and connects at the outside/recirculate vacuum motor, since it takes a real hot day and you pressing down on the accelerator to make the system default to Defrost. Try removing the lower right hand portion of the dash, up where the passenger's feet would go and look for a hose that goes all around the front and make sure it is connected. You may need a mirror to see if it is, but if the dealer pulled the dash too far, this would be the most likely place for the vacuum line to be disconnected."
In your other "Detailed info on vacuum leak" thread,I said:
"Thank you, Barry! That's exactly what I wanted and expected to hear!
If it always defaults on MAX, I know my theory is correct. I'll say it again, because this is what you'll tell the service department:
It's not just "behind the dash". The leak is definitely in the vacuum circuit to the recirculation door. Tell them MAX position always triggers the default."
Were we right???
Hey, Barry!
It's been a couple of weeks of summer heat. I'm really curious as to whether you got around to fixing the default.
Mr John said:
"But, if it was checked out as you said, the problem is probably an open or leak in the vacuum line that goes around the front of the plenum and connects at the outside/recirculate vacuum motor, since it takes a real hot day and you pressing down on the accelerator to make the system default to Defrost. Try removing the lower right hand portion of the dash, up where the passenger's feet would go and look for a hose that goes all around the front and make sure it is connected. You may need a mirror to see if it is, but if the dealer pulled the dash too far, this would be the most likely place for the vacuum line to be disconnected."
In your other "Detailed info on vacuum leak" thread,I said:
"Thank you, Barry! That's exactly what I wanted and expected to hear!
If it always defaults on MAX, I know my theory is correct. I'll say it again, because this is what you'll tell the service department:
It's not just "behind the dash". The leak is definitely in the vacuum circuit to the recirculation door. Tell them MAX position always triggers the default."
Were we right???