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when is the vacuum pump suppose to have power to it? What does it run? I have after market turn style lockouts, so I don't need it for them but does it control anything for the HVAC system? After my battery drain problem the HVAC doesn't change from defrost to floor or anything.
Possably I should not be posting for lack of knowledge but on my 01 350 4x4 the vacume pump is located under the hood over the right wheel. It gets power when you turn the key on and stops when the vacume chamber is charged. It pumps up so quick you almost have to have somebody else turn the key on while you stand by the front wheel with the hood open to hear it pump. If you have a leak it will not quit pumping. The defrosters only will work on my truck if you have no vacume, nothing else will shift. My vacume lines failed where they attached on to the backing plated for the auto hubs and also the pump it's self had to be replaced.
I hope some of this will apply to your problem.
I know where it is I just don't ever see it on now so I was wondering what turns it on and if it is used for the HVAC. It seems to me that it was always on before. When I use to turn the key you could hear it working???? at least I thought it was that. lol
Rubidon
Mine comes on with the key and pulls vacume to a point and shuts off and comes back on as needed. It does firnish the power to work the air heater controlls. If it runs all the time you have a leak or it is not pumping. If it doesn't run at all check to see if fuses are ok and if power is to it with the ign key on. If you have power to it and it does not run and you have no vacume as it has run up to preasure and shut off, then I would think you need a pump. I had to replace mine,100$ about. I think if it does not run you will only have a defroster.
Yes, it supplies control vacuum to the HVAC. I've learned the most common cause of vacuum leaks is the ESOF module for the 4X4. Did you bypass the ESOF module?
Ok so I am not getting any voltage to the vacuum pump. If I unhook the vacuum hoses from the canister it does not turn on and I am not getting voltage to the plug any time. Now my truck is an early '99 and does not have a #28 15amp under the dash. So now I need to know what to check now.
My truck is an early 99 also and I think in my handbook the blend control was 24 or 25 10 amp. My pump just went out on mine. 60.00 for the cheap one on Ebay. A Curtis
when is the vacuum pump suppose to have power to it? What does it run? I have after market turn style lockouts, so I don't need it for them but does it control anything for the HVAC system? After my battery drain problem the HVAC doesn't change from defrost to floor or anything.
The vacuum pump supplies vacuum to the HVAC system. If it is failing to actuate the blower door, this may be because of your manual hubs. Did you cap off the vacuum tubes to the hubs? Check the system for leaks.
I didn't bypass the ESOF module but it is plugged of by the vacuum canister. I think the problem is power related ! I don't know what fuses to check because the truck is an early '99.
Here's where you can get an owners manual. http://www.motorcraftservice.com/vdi...250+Super+Duty
Are you saying there is not a fuse in slot #28. If so, the manual says that is a 10 amp fuse for the ESOF hub lock solenoid.
Here's where you can get an owners manual. http://www.motorcraftservice.com/vdi...250+Super+Duty
Are you saying there is not a fuse in slot #28. If so, the manual says that is a 10 amp fuse for the ESOF hub lock solenoid.
Link does not work. If you put a fuse in the #28 spot it just falls out, if you use a flashlight and look into the slots there are no terminals there to hold a fuse.
Ok so I am not getting any voltage to the vacuum pump. If I unhook the vacuum hoses from the canister it does not turn on and I am not getting voltage to the plug any time. Now my truck is an early '99 and does not have a #28 15amp under the dash. So now I need to know what to check now.
#28 is not under the dash, its under the hood. In front of the fire wall on the drivers side