A/C only blows through vent
Thread Starter
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Laughing Gas
Joined: Aug 2007
Posts: 1,132
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From: Baldwin, ND
A/C only blows through vent
The A/C on my 03 F350 will only blow on vent. I know it could be a vacuum leak but I am not sure what to check after that. My brakes feel fine so I think it might not be the vacuum.
Any thoughts?
Thanks
Thad
Any thoughts?
Thanks
Thad
Senior User
Joined: Apr 2012
Posts: 294
Likes: 0
From: Orlando, FL
OK make sure it is in 2 wheel drive.... 
Check to see if the vacuum pump is turning on and attempting to draw a vacuum. If not look into fuse, relay or the pump itself. It it is trying to draw a vacuum. Behind the pump near the firewall there is a y where the vacuum goes to cab of truck and the wheels. Make sure you have good vacuum there and see if you can tell which side is leaking. From there it is find the leak. Most the time it is in the hub of one of the 4x4 wheels. For example my truck A/C is great however once I put it in 4x4 mode I go to defrost cause one of my hubs is leaking. I need to figure out which one and replace if I run the truck in 2 wheel drive it is fine.
Check to see if the vacuum pump is turning on and attempting to draw a vacuum. If not look into fuse, relay or the pump itself. It it is trying to draw a vacuum. Behind the pump near the firewall there is a y where the vacuum goes to cab of truck and the wheels. Make sure you have good vacuum there and see if you can tell which side is leaking. From there it is find the leak. Most the time it is in the hub of one of the 4x4 wheels. For example my truck A/C is great however once I put it in 4x4 mode I go to defrost cause one of my hubs is leaking. I need to figure out which one and replace if I run the truck in 2 wheel drive it is fine.
Thread Starter
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Laughing Gas
Joined: Aug 2007
Posts: 1,132
Likes: 0
From: Baldwin, ND
Thad
Thread Starter
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Laughing Gas
Joined: Aug 2007
Posts: 1,132
Likes: 0
From: Baldwin, ND
OK make sure it is in 2 wheel drive....
Check to see if the vacuum pump is turning on and attempting to draw a vacuum. If not look into fuse, relay or the pump itself. It it is trying to draw a vacuum. Behind the pump near the firewall there is a y where the vacuum goes to cab of truck and the wheels. Make sure you have good vacuum there and see if you can tell which side is leaking. From there it is find the leak. Most the time it is in the hub of one of the 4x4 wheels. For example my truck A/C is great however once I put it in 4x4 mode I go to defrost cause one of my hubs is leaking. I need to figure out which one and replace if I run the truck in 2 wheel drive it is fine.
Check to see if the vacuum pump is turning on and attempting to draw a vacuum. If not look into fuse, relay or the pump itself. It it is trying to draw a vacuum. Behind the pump near the firewall there is a y where the vacuum goes to cab of truck and the wheels. Make sure you have good vacuum there and see if you can tell which side is leaking. From there it is find the leak. Most the time it is in the hub of one of the 4x4 wheels. For example my truck A/C is great however once I put it in 4x4 mode I go to defrost cause one of my hubs is leaking. I need to figure out which one and replace if I run the truck in 2 wheel drive it is fine.
Thad
Senior User
Joined: Apr 2011
Posts: 322
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For a temporary fix on a hot day, With ac on in vent position run temp all the way up to 90 then back down, you might have to do a couple of times, ac should work out vent position.
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Senior User
Joined: Apr 2012
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From: Orlando, FL
More than likely. The vacuum is used to change vent blower position (default is defrost) and to engage the hubs for 4x4 if the truck is equipped with it. You may find if you put it back in 2 wheel drive it works normal like mine does. But more than likely it is a problem with the line to the hub.
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Thread Starter
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Laughing Gas
Joined: Aug 2007
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From: Baldwin, ND
Yeah, so I used the truck to go out scouting. Got stuck in a small ditch (seriously mad me mad...we have had over 4 unches of rain today though) because my 4x4 would not engage. Had my buddy tug me out. So I am fairly sure that its the vacuum and that I need to check it out in the next few days!
thanks
Thad
thanks
Thad
Posting Guru
Joined: Oct 2003
Posts: 1,198
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From: Tulsa, OK
OK make sure it is in 2 wheel drive....
Check to see if the vacuum pump is turning on and attempting to draw a vacuum. If not look into fuse, relay or the pump itself. It it is trying to draw a vacuum. Behind the pump near the firewall there is a y where the vacuum goes to cab of truck and the wheels. Make sure you have good vacuum there and see if you can tell which side is leaking. From there it is find the leak. Most the time it is in the hub of one of the 4x4 wheels. For example my truck A/C is great however once I put it in 4x4 mode I go to defrost cause one of my hubs is leaking. I need to figure out which one and replace if I run the truck in 2 wheel drive it is fine.
Check to see if the vacuum pump is turning on and attempting to draw a vacuum. If not look into fuse, relay or the pump itself. It it is trying to draw a vacuum. Behind the pump near the firewall there is a y where the vacuum goes to cab of truck and the wheels. Make sure you have good vacuum there and see if you can tell which side is leaking. From there it is find the leak. Most the time it is in the hub of one of the 4x4 wheels. For example my truck A/C is great however once I put it in 4x4 mode I go to defrost cause one of my hubs is leaking. I need to figure out which one and replace if I run the truck in 2 wheel drive it is fine.
On my Excursion, it was the 4x4 vacuum solenoid valve on passenger inner fender. Cracked wide open and had to be replaced. You could temporarily block off vac lines to this valve and/or hubs to restore A/C vent operation. Costs about $2 to get caps for lines.
Thread Starter
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Laughing Gas
Joined: Aug 2007
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From: Baldwin, ND
Benny, yeah it has the manual position but I couldn't turn the hub to the manual position (might need to check on that too!) and his rig was already where it needed to be (coincidence) and I had a tow strap in the bed....I was a little frustrated and just wanted to get back to hunting.
I hope to check on things tomorrow. I happen to already have a hand vacuum pump so it should be easy enough to diagnose.
thanks
Thad
I hope to check on things tomorrow. I happen to already have a hand vacuum pump so it should be easy enough to diagnose.
thanks
Thad
Senior User
Joined: Oct 2009
Posts: 138
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From: Maple Valley, Wa
You probably sucked a bit of water through a vac line and killed your pump. I did the same thing about two weeks ago on a jobsite. The pump is $100 at O'reillys. Clean out your hubs and your vaccuum chamber before you change it though
Thread Starter
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Laughing Gas
Joined: Aug 2007
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From: Baldwin, ND
The pump is good.
I gave the rig a once over and messed with a few lines (it started to downpour so I quit).
The leak is downstream from the 4x4 actuator in the passenger side engine compartment. Not sure where to look from here since most of the vacuum connections are not the type I am used to. Not sure if I can disconnect them and then reconnect them immediately without further leaks or issues.
Any thoughts?
Thad
I gave the rig a once over and messed with a few lines (it started to downpour so I quit).
The leak is downstream from the 4x4 actuator in the passenger side engine compartment. Not sure where to look from here since most of the vacuum connections are not the type I am used to. Not sure if I can disconnect them and then reconnect them immediately without further leaks or issues.
Any thoughts?
Thad