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A/C Problem
Thread Starter
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Senior User
Joined: Apr 2008
Posts: 469
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From: Santa Fe, NM
A/C Problem
I know that somebody has probably posted this elsewhere, but I can't find it. The A/C on my '99 F-250 blows nice and cold, never a problem in that area, but it only blows out of the defrost. No matter what setting you put it on that is the only place that the air comes out of.
Any ideas?
Any ideas?
Elder User
Joined: Dec 2004
Posts: 819
Likes: 3
From: Putnam Valley, New York
A/c-defrost Only
You have no vacuum to the control panel. The way the system is designed, is that when the vacuum fails, the system switches to defrost so you can keep your windshield clear. Listen in the cab for a hissing sound with the engine running. If you hear something, pinpoint it and fix it. You didn't say if your truck is a diesel or a gasser. If it's either, check under the hood for a split plastic vacuum line--as the truck gets older, those plastic lines get brittle and break. If your truck is a diesel, besides checking for a split line, you also have a vacuum pump which supplies vacuum for the 4WD & the heater-A/C. The vacuum pumps fail, so if you cannot find anything inside or under the hood, then I would suspect a failed vacuum pump.
RON
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Your is a VERY common problem.
You indicate your rig is a 7.3, but not whether it's 4WD or not.
If your truck is a 4WD, check the vacuum lines behind each front tire. Take the front tires off and you'll see them, bundled with the flexible brake line hoses and ABS sensor cables. There is one on each side that goes to the vacuum-operated "automatic" hub locks. Those small hoses are usually what goes first.
If that's what's leaking, replace them with 22-1/2 inches of 3/16" (4.8mm) SAE 30R7 fuel hose each side. It's a perfect fit, and should last a lot longer than the stock vacuum hose. Be sure to run each through the original plastic clips to maintain the proper routing.
It's way cheaper than a pump, and may be all you need.
Pop
You indicate your rig is a 7.3, but not whether it's 4WD or not.
If your truck is a 4WD, check the vacuum lines behind each front tire. Take the front tires off and you'll see them, bundled with the flexible brake line hoses and ABS sensor cables. There is one on each side that goes to the vacuum-operated "automatic" hub locks. Those small hoses are usually what goes first.
If that's what's leaking, replace them with 22-1/2 inches of 3/16" (4.8mm) SAE 30R7 fuel hose each side. It's a perfect fit, and should last a lot longer than the stock vacuum hose. Be sure to run each through the original plastic clips to maintain the proper routing.
It's way cheaper than a pump, and may be all you need.
Pop
Thread Starter
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Senior User
Joined: Apr 2008
Posts: 469
Likes: 0
From: Santa Fe, NM
First off, I'd like to thank you guys for helping out. Now I'm going to put you on the spot again...
Now call me stupid, but should there be another hose on the nipple? If so, where does it go?
Now call me stupid, but should there be another hose on the nipple? If so, where does it go?
More Turbo
Joined: Aug 2006
Posts: 530
Likes: 2
From: W. Wisc
Looks like it could be a vent/dump port to the atmosphere. Don't know the specific actuator you are pointing to, so it is only a guess.
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Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Sealboy,
You didn't tell us how you fixed your vacuum problem.
Please, always come back and let us know what actually fixed the problem, as that way the next guy with the same thing will know.
Pop
You didn't tell us how you fixed your vacuum problem.
Please, always come back and let us know what actually fixed the problem, as that way the next guy with the same thing will know.
Pop
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Thread Starter
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Senior User
Joined: Apr 2008
Posts: 469
Likes: 0
From: Santa Fe, NM
Is this the vacum pump that would control the different A/C settings?
Is there a hose that needs to be attached to this nipple?
If so where does the other end go?
Do you need a better picture?
Like I said, call me stupid....
Thanks in advance
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Yes, there is a hose connected, and it is only about six or seven inches long. It loops back to the opposite end of this solenoid, as seen in the photo below.
Be sure to check the flex lines down at the spindles, too! That's the most common area to leak.
Pop
Be sure to check the flex lines down at the spindles, too! That's the most common area to leak.
Pop
Thread Starter
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Senior User
Joined: Apr 2008
Posts: 469
Likes: 0
From: Santa Fe, NM
Ok, Problem fixed!
The first thing I did was have my grandson sit in the passenger seat with the A/C on. I disconnected one of the small hoses, and using a small pump that I reversed the motor on I hooked it up. The A/C immediately switched to the dash.
I decided that I should then check and see if the pump was getting power. I had my socket set sitting there in case I needed to remove the pump. In the process of hooking up my volt meter I knocked the socket set onto the pump. I guess it was getting power, 'cause it started right up.
I guess it is like any other small motor, and when it starts to go, the insides get kind of gummed up. It is really loud, and I am sure that it is not long for this world.
Thanks for all of your help on this matter. I'm sure there will be more.
The first thing I did was have my grandson sit in the passenger seat with the A/C on. I disconnected one of the small hoses, and using a small pump that I reversed the motor on I hooked it up. The A/C immediately switched to the dash.
I decided that I should then check and see if the pump was getting power. I had my socket set sitting there in case I needed to remove the pump. In the process of hooking up my volt meter I knocked the socket set onto the pump. I guess it was getting power, 'cause it started right up.
I guess it is like any other small motor, and when it starts to go, the insides get kind of gummed up. It is really loud, and I am sure that it is not long for this world.
Thanks for all of your help on this matter. I'm sure there will be more.
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