air conditioning coming out of defrost only

[outlaw_iii]

hey guys,
i have a 2000 ford f-250. the air conditioning will only come out the defrost. i thought the problem was the vacuum pump, after i had put a pump that my buddy had in his truck (it was electric) on, everything worked fine, including switches and everything else. so i went to the ford dealer today got the new vacuum pump, and air is still coming out of the defroster. the only other thing i think it could still be is what my friend called the boost canister, or vacuum booster. it was pressurized and didnt leak, but something rattled around inside, could this be my problem? this canister is just in front of the pump is 6 or 8 in heighth, same in length, and oval in shape. any suggestions?
thanks,
john

[wrongway]

Check the vacuum hose coming out of the frame behind front tire's. The hose goes from the frame to the inside of the hub. The hose's tend to dry rot after awhile, and create a vacuum leak. [img]/ubbthreads/images/graemlins/biggrin.gif[/img]

[DENNY]

Also look under the passenger side dash for the dash vaccume controls they can come loose.
DENNY

[cjheap]

Mine does this when I put it on MAX and it does not get cold any more. How do I check the pump? I have already plugged off the hub hoses BTW.

[ QUOTE ]
Also look under the passenger side dash for the dash vaccume controls they can come loose.
DENNY

[/ QUOTE ]

[firetruckin]

I have the same year truck and I have the same problem. I have the manual hubs on mine. Do I still have vacuum lines going to the hubs or is that just for the auto hubs? My A/C switches itself to the defrost vents when outside temps are up and the truck is working hard (like pulling my trailer up a long steep hill). Can anyone post pictures of the various hoses and their locations? After I let my truck cool down for awhile the A/C begins working properly (usually).

[gcoutlaw]

My a/c blows out the defrosters when I put the 4x4 selector switch into 4high! I just put WARN premium hubs on mine and got rid of the ESOF but I have not capped off any lines as of yet. The front hubs are in FREE and I switch to 4HIGH in the cab and it starts blowing out the defroster (turning back to OFF and turning the a/c off and then a few minutes all goes back to normal). Again, it did this before the WARN replacements too! My ESOF failed and I did not need that system anyway and opted for what some considered much stronger hubs per this website? Wish I could figure out what is going on here!

[swabadger]

The switching mechanism to go from defrost to the vents is vacuum controlled and it defaults to defrost with a decrease in vacuum. I had this problem on 96 Bronco and it was the vacuum check valve that had failed, turned out to be something like a $5 dollar part. The dry-rotted hose would be a good place to look as well. gcoutlaw- cap the lines and it will work fine.

[DieselSteve2008]

Mine also blew air from defrost vents when I switched to 4x4 and it turned out to be the vacuum solenoid that is mounted to the passenger side firewall just behind battery. Very easy to replace and about 60 bucks from the dealer.

[MARCSPSD]

I have the same problem and am going to try to fix it this weekend. 2001 PSD 4x4 Ex

First I will try to find the leak. (everybody seems to agree this is the problem with the symtoms you described)

The hubs can be leaking: Pull off the air line to each hub and pressurize with a vacuum gage. If either hub cannot hold pressure then that is the problem. (anybody know how much pressure should be applied?)

Next check the hoses and then the vacuum solinoid on the firewall. Find and fix the leak and your 4 x 4 front hubs should operate and your ac vents as well. However, I am no expert, just a weekend driveway warrior! If the ac is not blowing cold then that is a different issue i think.

[gcoutlaw]

As stated initially, I thought it was the hubs so I put on some Warm Premium hubs that I know manually lock or unlock (read some other posts, did not know any better).

Now, with that being done, I have not capped off anything as of yet so I presume I should put a cap on the line inside the fender wells up front where the line connects to the tab mounted to the frame and where that hose goes down to the front axle? Capping this off would maybe help as I guess now I have nothing to pressurize given I just took off the stock hubs? I guess I should also put a cap down on the bottom of the hose where it connects to the axle if I remove that hose to make sure no water or debris gets in there too?

I guess if none of this works, I do the selinoid or whatever behind the firewall?

[MARCSPSD]

Yesterday I went to the Ford dealer to buy parts to try to fix this situation. I was planning on buying hubs, vacuum lines and vacuum solonoid. When I found out that my local dealer now charges a 20% restocking fee on all parts returned, I decided to take a look at the truck first.

Thank you Wrongway, as that was my problem. The old vacuum lines from the hub to the connection on the firewall were rotted out. Went to the auto parts store and bought 5ft of vacuum line (seems higher quality than stock) and installed new lines on both sides. (had some line left over)

PROBLEM FIXED for less than $4.

Thanks to this site for the help and info!!

[unclebuck65]

I'm having the opposite problem, my 01 psd only blows from defrost and I have changed the hub vacuum hoses with no help. Recently I had to put it in 4X4 and the air flow was running normal once again. When I went back to two wheel drive my problem was back,defrost only. Any help?

[climber417]

drive in 4x... haha I'm having the same problem my 4 wheel wouldnt kick in one night and thats when i figured out that the problem was related with heater and 4x....

[jainkelly]

air conditioning replacement parts

Mobile Air Spares is one of the leading company in Cab-Aire spare parts. Mobile Air Spares provide spare parts for all commercial vehicle air conditioning parts throughout Australia.