my auto locking hubs quit working a while ago> last time I tried them I had the ac on and it started blowing through the defroster. it doesnt have any vacuum to the hubs. has any body had this problem?
thanks Trash

 

You have a vacume leak in your system. the hubs use vacume to lock and unlock. The a/c system also uses vacume and when you lose vacume pressure the defrost is the default position.

 

thanks for the reply I know it has a vacume problem I just cant find it . when I turn the switch it sounds like a small compressor starts under the hood is there a common problem that causes this.
this is a 2003 f250

 

The sound you here is the vacume pump. On the passenger side wheel well there is a small unit with wires and two vacume lines,(4wheel drive module) It could have gone bad like mine did. Or a vacume leak in one of the lines going from that unit to the wheel hubs. Or one of the seals in the wheel hub/locking hub.

 

how can I test the pump how much vavume should it have
and what about the ait tank looking thing is that part of it as well

 

Well....first thing I woud do is disconnect the vacume lines at the 4wheel drive mod, plug them, turn on the key and wait for the vacume pump to build up vacume, and turn your selector to 4x4, listen for the sound you have been hearing. If it is gone then U know it is not the vacume pump but it is in the 4x4 system

 

good idea thanks

 

check your inbox

 

what inbox?

 

I sent you a Private message

 

Sorry...I guess you cant get a pm...

 

thats what I thought you ment but im not showing any inbox. maybe the site is having problems

 

Not sure...maybe you need to set it up.

 

replace with warn hubs and get rid of all the problems

 

Troubleshooting vacuum issues:

First locate the vacuum pump on the passenger side fender well. Make sure it works by listening with the key on - it should be vibrating.

Next unplug the vacuum harness at the resevoir and cover with a finger to make sure it turns off. Install a vacuum pump into the hose (the pump should pull 25+ " of vacuum within seconds). If that is ok, then reconnect the pump line to reservoir inlet and vacuum pump to outlet to make sure the reservoir will hold vacuum. If thats good, follow lines to the "tee" were they split. You will see two lines ..... one goes to the front end and the other to the dash. Disconnect the lines and hook up the vacuum pump to each line, one at a time. Pump the gun to 20" or so and monitor for 5 minutes to insure they do not drop vacuum. 90 percent of the time the problem is the line going to the front end. If the front end is causing the problem, then jack up the front end disconnect the vacuum lines to front knuckles. Pump to around 20" of vacuum while spinning tires to see if it drops vacuum. If either one does, then add 3-5 psi of air to the knuckle and spray with soapy water to find the leak. You can either fix the leak or cap off the line up top and run your hubs manually.
If the dash and the front end lines hold vacuum, then cap both lines off with a golf tee or equivalent.

Pump the line from reservoir to vacuum control solenoid to find the problem.

Also if the grey vacuum line that goes either to the hot water shut off in the heater hose or to the evaporator case is hanging loose, it should only cause a problem in max a/c.

If the problem is in the dash just keep unhooking vacuum lines and plug one end and pump the other until you find the leak.