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Dash air problem


saflyer
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I was on a long trip in August. Most of the drive the dash air worked as expected. At one point the air from the dash vents became nil. I don’t recall if I noticed this mid-drive or when first turned on. After some time I discovered the air was flowing from the windshield defrost vents at a level you would expect based on the fan speed setting. Now I hadn’t selected defrost since last winter, only AC and vent.

I have a friend with another HR coach who has some experience troubleshooting AC systems. We found what we believe is the vacuum pump above generator. We disconnected the tube from it to the reservoir and found no suction. We checked the two wires from this part and found 0 voltage regardless of engine on or off, AC on or off or AC mode. I have fan power so the one fuse listed in the front run bay must be good, am I right? Can anyone educate me on the AC system and how this part works? 

Ed            
’05 HR Ambassador

 

 

313F11E9-2021-460D-8C0D-832673D5B2A2.jpeg

Edited by saflyer
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Ed,

That is an electrical vacuum generator versus what my Windsor has which is a air generated vacuum using a venturi effect.

Is there a fuse that controls the vacuum generator?

Your first course of action would be to find out why the generator has no power to it. I would think that once you turn on the AC/Heat Controls that the vacuum generator would have power going to it. That vacuum controls the directional air chambers as to which vents the air flows out of. The default vent is the defrost vents on top of the dash near the front windshield.

 

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1 hour ago, Dr4Film said:

Ed,

That is an electrical vacuum generator versus what my Windsor has which is a air generated vacuum using a venturi effect.

Is there a fuse that controls the vacuum generator?

Your first course of action would be to find out why the generator has no power to it. I would think that once you turn on the AC/Heat Controls that the vacuum generator would have power going to it. That vacuum controls the directional air chambers as to which vents the air flows out of. The default vent is the defrost vents on top of the dash near the front windshield.

 

I think that’s going to be the trick, finding a fuse for that vacuum pump.

Your point of the the defrost vents being the “default” position would explain their operation without my ever selecting them.

Thanks,      
Ed

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We had the same symptom (air out the windshield vents) due to the vacuum pump failing in our 2000 Diplomat. It was tripping a breaker, which on ours is shared with the steps. Our fuse is labeled "VAC SENSE" on the inside of the cover in the outside electrical bay below the driver. It's pretty easy to swap out the pump.

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10 hours ago, saflyer said:

I was on a long trip in August. Most of the drive the dash air worked as expected. At one point the air from the dash vents became nil. I don’t recall if I noticed this mid-drive or when first turned on. After some time I discovered the air was flowing from the windshield defrost vents at a level you would expect based on the fan speed setting. Now I hadn’t selected defrost since last winter, only AC and vent.

I have a friend with another HR coach who has some experience troubleshooting AC systems. We found what we believe is the vacuum pump above generator. We disconnected the tube from it to the reservoir and found no suction. We checked the two wires from this part and found 0 voltage regardless of engine on or off, AC on or off or AC mode. I have fan power so the one fuse listed in the front run bay must be good, am I right? Can anyone educate me on the AC system and how this part works? 

Ed            
’05 HR Ambassador

 

 

313F11E9-2021-460D-8C0D-832673D5B2A2.jpeg

Where was this located?

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This Vacuum Pump/Generator is from a Ford Diesel Pick up truck. The Monaco P/N is 01802268, the Ford P/N is E3 HT2A451 BA. They are available at any Auto Parts Store and Amazon List them for $70.00.

There is only power going to the Vacuum Generator when it senses the Dash AC System is Low or no vacuum.  The round black reservoir above the the pump stores vacuum for the Dash AC system to operate and the Pump/Generator keeps it full.

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  • saflyer changed the title to Dash air problem
10 minutes ago, David Pratt said:

This Vacuum Pump/Generator is from a Ford Diesel Pick up truck. The Monaco P/N is 01802268, the Ford P/N is E3 HT2A451 BA. They are available at any Auto Parts Store and Amazon List them for $70.00.

There is only power going to the Vacuum Generator when it senses the Dash AC System is Low or no vacuum.  The round black reservoir above the the pump stores vacuum for the Dash AC system to operate and the Pump/Generator keeps it full.

So that leads me to a failed sensor. Where should I look for that?

Thanks

53 minutes ago, Robertpk said:

Here is a copy of the wiri g to the vac. Pump. Hope this helps.

Great. Really helps.

Thanks

Is the vacuum sensor in the vacuum generator? I think that might be why David led me to replacing it. Am I reading this right?

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Generally speaking with these pumps in the Ford trucks I saw the failure due to constant running, usually due to a vacuum leak the customer never knew they had. With ford it was sold as a complete unit, just be prepared once it is replaced if the pump continues to run while the key is in the on position your going to have to start looking for the reason. Most of the trucks had a vacuum tank that would be a "storage container" for the vacuum??? (sounds weird saying it that way) so it was kinda normal that overnight you would get some brief operation when you turned the key on, and also brief operation when making vacuum requests (a/c mode selection, or with Ford trucks 4wd selection) however for the most part there are to be no leaks so the system would stay off.

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OK help me out here. David, are you saying the wires to the pump are only powered when the vacuum is low implying the sensor for that is external to the pump. Or should there be power at all times and the circuit is only closed if a sensor internal to the generator senses inadequate vacuum, closes a switch starting the generator. That implies there is something elsewhere causing the problem and not the vacuum generator itself.

I ask this because of something I saw in the wiring diagram Robertpk supplied. I don’t recall if these two issues started at the same time but they might have. My steps are not retracting normally. If the step switch is in the off position the steps should remain extended regardless of whether the entry door is open or closed except if the door is closed and the ignition key is turned to the on position. Then the steps retract to protect them during driving.  Recently, and again it might have started at the same time as the AC issue, my steps don’t retract when the switch is in the down/off position, the door is closed and the ignition switch moved to the on position. I have to put the step switch in the on/up position for the steps to retract for driving. Could there be the common link here? What is the ignition switch connected to in relation to the entry steps? (BTW, as an aside, the light in the door switch has never illuminated.)

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The sensor is built into the pump itself! You will have to replace the pump if it not working. You can test the pump by first removing the Vacuum hose from the pump, turning on the ignition, select a mode other than Defrost and the pump should run continuously until you connect the hose back on the pump. When the Vacuum pressure builds up the pump will turn off, If the pump does not turn off, you have a vacuum leak somewhere in the system. If it fails to run the pump is junk.

As Rik stated, most of the failures with these pumps occur because of an undetected vacuum leak and they run constantly. They were not designed to do that.

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My pump has 12v power when the key is on.  The amount of vacuum is controlled inside the pump its self.  You can supply 12v to the pump to test it.  A cover on the pump can be snapped off to expose the contacts that sometimes cause it to not operate, I have done that to mine before and made it work for years now.  Since the steps and vac pump are ingnition sw related it seems possible your problems may be related too

Robert's diagram shows that the pump and step are fed through the same connector, find that common connection and clean it and you may solve both issues.  Lets hope it will 

Edited by Ray Davis
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Posted (edited)
3 minutes ago, David Pratt said:

The sensor is built into the pump itself! You will have to replace the pump if it not working. You can test the pump by first removing the Vacuum hose from the pump, turning on the ignition, select a mode other than Defrost and the pump should run continuously until you connect the hose back on the pump. When the Vacuum pressure builds up the pump will turn off, If the pump does not turn off, you have a vacuum leak somewhere in the system. If it fails to run the pump is junk.

As Rik stated, most of the failures with these pumps occur because of an undetected vacuum leak and they run constantly. They were not designed to do that.

That was my original thinking. But if there is no power in the wires to the pump it can be good but still not work. That’s my situation. Why is there no power to the wire’s?

Edited by saflyer
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I am sorry but what I meant is that the pump will only run when the system is low on vacuum. The ignition switch must be on and the AC control selected to a Mode for the pump to have power. The internal sensor in the pump will turn the pump on and off. The round black reservoir stores enough vacuum to assist the pump when you switch modes and prevent the pump from running constantly.

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Easiest way to check the pump is to get two jumper wires and connect it directly to a battery. I carry a small 12vdc 12 amp battery that they use in computer back ups to trouble shoot with. I have a lead with alligator clips. It works well to be able to trouble shoot components at the source without having to remove them.

When you turn on the ignition switch you will have power that goes directly to the AC control panel. When you switch the panel from off to any other mode it will activate the pump if the vacuum is low to move the affected actuators. There should be an accessory fuse located in the front run bay that controls power to the AC control. You need to refer to the wiring diagram for your coach.

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29 minutes ago, David Pratt said:

I am sorry but what I meant is that the pump will only run when the system is low on vacuum. The ignition switch must be on and the AC control selected to a Mode for the pump to have power. The internal sensor in the pump will turn the pump on and off. The round black reservoir stores enough vacuum to assist the pump when you switch modes and prevent the pump from running constantly.

I don’t see in the step/vacuum generator wiring diagram in the earlier message where the ignition switch comes into the picture. Does the key connect power directly to the vacuum generator or does it go through some other devices. IOW, what path do I follow to trouble shoot it as I am getting no voltage at the vacuum generator with the key and the AC in the on positions.

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Look at the diagram, left lower connector.  It says front dist panel , 7.5A fuse.  I think it says fuse # 19 but it's not clear enough for me.

We would need additional diagrams to see where it ties in with the ignition sw from there.   If the 7.5A fuse fixes it I guess it wouldn't matter how it all connects to the ign.

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The front dist panel is connected to the Ignition/run source from the Ignition switch. The dist panel is powered up whenever the ignition switch is turned on thus any or all fuses or components on that Dist panel are powered up and feed other components from that board, such as the AC system.

Have you determined if the pump is working by jumping it as suggested.

Is that wiring diagram applicable to your coach? I do not have a wiring diagram for your coach. On the 05 Dynasty, Exec, Sig and Navigator there is a 25 amp fuse that powers the AC control in the dash, the vacuum generator and the evaporator fan,

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On 10/1/2021 at 2:44 PM, David Pratt said:

.Have you determined if the pump is working by jumping it as suggested.

 

Finally got some test leads that work. Yes, the pump operates. So it’s back to the ignition issue.

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Do you have the wiring schematic manual for you coach. You will need it to properly chase down you wiring problem, Without it, it is like looking for a needle in a haystack.

On the distribution panel where the 7.5 amp fuse is located, there is also a 20 amp fuse. The 7.5 amp fuse is labeled F-19and is for the vacuum generator. The 20amp fuse is labeled F-13 and powers the AC control in your dash. You need to check these fuses and check for power. There are several fuses that control the functions of the cab AC and also a few relays. The distribution panel will be powered up whenever the Ignition is turned on, so the fuses should be hot also.

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On 10/1/2021 at 1:33 PM, Ray Davis said:

Look at the diagram, left lower connector.  It says front dist panel , 7.5A fuse.  I think it says fuse # 19 but it's not clear enough for me.

We would need additional diagrams to see where it ties in with the ignition sw from there.   If the 7.5A fuse fixes it I guess it wouldn't matter how it all connects to the ign.

Unfortunately when I make the diagram large enough for my eyes the letters are too fuzzy to read. I appreciate the effort of the person who posted it but I can’t read it.

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Posted (edited)
On 10/1/2021 at 7:07 AM, Robertpk said:
On 10/1/2021 at 7:07 AM, Robertpk said:

Here is a copy of the wiri g to the vac. Pump. Hope this helps.Screenshot_20211001-080512_Drive.thumb.jpg.689456d93573ae2defc5c147c35350e5.jpg

Thanks to Robertpk’s post that showed a relation between the entry step and the A/C I checked the fuses for the step. One of them was burned. Replaced it and all works correctly. Remains to be seen if it was a one time event or there is a deeper problem.

Edited by saflyer
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