A/C Only blowing out of defrost? - Ford Mustang Forums
Reply
 
LinkBack Thread Tools
post #1 of 16 (permalink) Old 05-28-2012 Thread Starter
Apprentice
5.0L Member
 
727LOUIS's Avatar
 
Joined: Mar 2012
Location: Seminole
Posts: 123
 
A/C Only blowing out of defrost?

Whats up AFM, I'm a newer mustang owner I have a '95 gt. The A/C only works on the MAX AC setting and only blows out of my defrost... Anyone know what could be causing this?
727LOUIS is offline  
Sponsored Links
Advertisement
 
post #2 of 16 (permalink) Old 05-28-2012
GT Member
4.6L Member
S197 Member
 
marylandGT's Avatar
 
Joined: Mar 2011
Location: Pasadena
Posts: 1,687
 
Garage
When you set it to "vent", do you get air blowing out the dash? If not, sometimes the linkage that operates the opening and closing of the vents will get hung up. Could be just alot of dust and dirt on them. Try to get behind the dash and follow the connections from the directional dial to the air ducts.
marylandGT is online now  
post #3 of 16 (permalink) Old 05-28-2012
MACH I Member
5.0L Member
 
Tominator's Avatar
 
Joined: Nov 2003
Location: Cahokia
Posts: 2,739
 
Most likely you have a broken vacuum line or one has come off at a connection. Vacuum is what the controller on the dash routes to the various controls that route the air.

Make sure that the vacuum canister is connected. That is under the hood. Black globe about the size of a grapefruit.

Next check under the dash. You might need to disassemble various trim pieces to get to it.

There is also a resistor inside of the duct work that can burn out.

Someone a little more familiar with your year Mustang will chime in shortly any time now...

'95 Ranger 5.0 GT40X Tri-y GT40 Intake S-Trim Snow Stage 2 Lowered Baer Racing Brakes Viper Spec Tremec w/Hurst shifter Custom Interior Dakota Digital Dash Corbeau Toplines OZ Racing AM/FM/Mp3/CD/DVD/TV.

2014 GTIG 5.0 Vert. Sil Carb Fiber dash. Bama Race Tune. Gibson axle backs. STEEDA Springs KONI STR.T Adj. Panhard
Tominator is offline  
post #4 of 16 (permalink) Old 05-28-2012
Rookie
5.0L Member
 
leperchaun's Avatar
 
Joined: May 2011
Location: Edmond
Posts: 38
 
It sounds like you have two issues. One being its not switching from defrost to vent. Second it is only blowing on high speed. I can help with the defrost issue and i will try with the fan issue. Maybe someone else that has faced the fan only on high issue can better help you with the second issue.

My 95 gt would only blow out the defrost vent. With mine it was a vaccum leak. Under you hood on the passenger side of the car there is a vaccum line that passes through the fire wall from the pasenger compartment in to the engine bay. It routes along the firewall towards the drivers side. It plugs into a black plastic vaccum terminal (for lack of a better name) that is mounted on the drivers side fenderwell right behind the strut tower and above the brake booster. Mine had simply gotten brittle and had a small crack in it. I replaced this vaccum line and it now switches from vent to defrost.

Switching from defrost, to vent, to floor is controlled by this vaccum line. As far as it only blowing on high that is controlled electricly via a switch. Im not sure on this but on many cars the fan has a series of resisters that (these are mounted in side the fan motor housing) controll the speed of the fan via the switch sometimes the resisters will burn out and only high speed works. Most people just replace the fan motor. My car didnt have a issue with fan speed just the vent not switching. i can almost promise you that the vaccum line is the problem with your vent not switching. I hope this helps.

My therapist said "your not crazy.......see ya next week"
leperchaun is offline  
post #5 of 16 (permalink) Old 05-29-2012 Thread Starter
Apprentice
5.0L Member
 
727LOUIS's Avatar
 
Joined: Mar 2012
Location: Seminole
Posts: 123
 
Thanks a lot!! It was just the vaccum line! Haven't had a chance to check the resistors but I will this week.
727LOUIS is offline  
post #6 of 16 (permalink) Old 07-27-2012
Rookie
 
PuneyPony's Avatar
 
Joined: May 2012
Location: Delware County
Posts: 34
 
For Future Reference

I know this is an older thread, but someone will stumble across this like I did. While it is true that a series of vacuum lines control the mixture and temperature, the fan speed is actually electric controlled. In most cases, a plug and play style resister can be found under the glove box. It is easily visible, and bolts right with two tiny 8mm (i think) bolts. I took less than five minutes to take my old one out and swap in the new one. The is nothing to remove in order to access it. It simply sits right there in the duct work. The resistor module is actually cooled by the airflow in the duct work because it gets pretty hot. When running the blower on low speeds, the resistor actually burns out partially, after some time. I bought a replacement Borg Warner module at Advanced Auto btw, and it was only 10-15 bucks.
PuneyPony is offline  
post #7 of 16 (permalink) Old 07-28-2012
Apprentice
 
1995Beast's Avatar
 
Joined: Feb 2009
Location: Saucier
Posts: 216
 
Quote:
Originally Posted by PuneyPony View Post
I know this is an older thread, but someone will stumble across this like I did. While it is true that a series of vacuum lines control the mixture and temperature, the fan speed is actually electric controlled. In most cases, a plug and play style resister can be found under the glove box. It is easily visible, and bolts right with two tiny 8mm (i think) bolts. I took less than five minutes to take my old one out and swap in the new one. The is nothing to remove in order to access it. It simply sits right there in the duct work. The resistor module is actually cooled by the airflow in the duct work because it gets pretty hot. When running the blower on low speeds, the resistor actually burns out partially, after some time. I bought a replacement Borg Warner module at Advanced Auto btw, and it was only 10-15 bucks.
+1 on that response

5.0-Clean Machine
BBk under-drive pullies, BBk LT headers, BBk CAI, SCT chip, Edlebrock Performer Intake
1995Beast is offline  
post #8 of 16 (permalink) Old 07-30-2012
Apprentice
5.0L Member
 
386 stang's Avatar
 
Joined: Oct 2011
Location: Palm Coast
Posts: 194
 
my car dose the same thing only blows out of the defroster havent dun a vaccum test on it but i did change the line that gose thru the fire wall an it still dosent work think the tree could be cracked somewere ?
386 stang is offline  
post #9 of 16 (permalink) Old 08-31-2012
Rookie
 
PuneyPony's Avatar
 
Joined: May 2012
Location: Delware County
Posts: 34
 
For those who do not know and reference this thread in the future, vacuum is what controls the airflow mixture settings for the air conditioner/heater and is totally independent of the fan speed control. Focusing on the problem at hand, the tree is tough and chances are it is not cracked. However there is a problematic, black vacuum line that runs from the driver side all the way across to the passenger side along the firewall and then into the passenger firewall. This is the only vacuum line that usually causes problems right out of nowhere. It becomes brittle and almost "dry-rot" due to engine heat and age. Sometimes it could be fine, but simply became detached simply by bumping into it while working around it. I am willing to bet your leak is right at the fitting coming off of the main tree. If not there, follow your way down the line checking for breakage or cracks. They are usually obvious. Once you find it, you can cut bad parts off of the bad line and replace whatever connectors you need. Reattach a newly re-cut ends back into the tree with new connectors of the correct size. If the crack is in the middle of the line, cut the pab parts off of the line and insert a bridge connector of the correct size to fill the gap. Be careful not to cut away too much of the line, other wise you will be replacing that whole vacuum line. Still, replacing the whole vacuum line is one of the simplest things to do on that car. You can find a pack of assorted vacuum line fittings of different types and sizes made by Dorman (Makers of HELP!) in almost every auto parts store.
PuneyPony is offline  
Rookie
 
PuneyPony's Avatar
 
Joined: May 2012
Location: Delware County
Posts: 34
 
386Stang - Have you checked the main vacuum tree for cracking? Have you been working near that area prior to your symptoms? I would check any hoses between the tree and the motor.
PuneyPony is offline  
Rookie
 
PuneyPony's Avatar
 
Joined: May 2012
Location: Delware County
Posts: 34
 
Quote:
Originally Posted by 386 stang View Post
my car dose the same thing only blows out of the defroster havent dun a vaccum test on it but i did change the line that gose thru the fire wall an it still dosent work think the tree could be cracked somewere ?
Hey Buddy, I just thought of this. Even though you cant control your mixture settings (e.g. you are stuck on defrost), can you adjust the temperature from hot to cold? If there was absolutely NO presence of vacuum, you would not be able to control the temperature either. If you can control the temp the issue might be narrowed down to lines or connectors under the dash or the control unit itself. This brings to mind the time I replaced the same vacuum line you are doing. My temp worked, but mixture did not. The culprit was that I had reconnected the same vacuum line you are replacing the wrong way into the vacuum reservoir behind the glove box. The vacuum line I was working on was confused with another line on the unit the fell off while I was working on it. I had the lines reversed. When I went back in and corrected this, all was good and everything functional. You can actually feel for live a/c vacuum here as well and should narrow things down a bit.
PuneyPony is offline  
PONY Member
5.0L Member
 
The_Mustang's Avatar
 
Joined: Sep 2009
Location: Jax
Posts: 254
 
I was going to suggest taking a look at the vacuum reservoir behind the glove box. I've seen the nipple on those get broken off as well.

1999 Mustang - Converted to 94 spec 5.0 EFI,
Vortech V2 SQ 12 psi, BBK shorties, Edelbrock Perf. intake,
The_Mustang is offline  
Apprentice
5.0L Member
 
386 stang's Avatar
 
Joined: Oct 2011
Location: Palm Coast
Posts: 194
 
Yes I have checked for cracks nothing that I can see an its been like that since Ive had the car
386 stang is offline  
Rookie
 
kennyfender's Avatar
 
Joined: Sep 2012
Location: Hampton
Posts: 30
 
i have a 95 gt. there is a small vacuum hose made of plastic it is smaller than a pencil running from a tree on the drivers side that has four lines and the small one is the third one down. mine broke right at the tree. when this happens the car goes into default mode and blows out the defrost. sucks. i pull the rubber connector off the tree and got the lil brok piece out and just stuck new end in and it worked. hope its as easy as that for u but if not ford place def can fix it. it took me like 15 mins though
kennyfender is offline  
Rookie
 
mattmathis's Avatar
 
Joined: Mar 2014
Location: Ocilla
Posts: 7
 
Pardon me digging up this ancient thread, but I found it in a search...

I'm having this same problem and traced it down to the vac line is broken off right at the firewall. I cant get any slack to put a fitting on. So I guess I need to replace it. But I can't find a how-to anywhere. Can anyone tell me how this is done? Behind the glove box or must the whole dash come out?
mattmathis is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Ford Mustang Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a VALID email address for yourself, otherwise you will not receive the necessary confirmation email needed to confirm, validate and activate your new AFM member account.

Failure to provide a VALID email address, will result in the cancellation of your new AFM member account registration.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182