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  #1  
Old 07-08-2011, 01:56 PM
brotherstorm brotherstorm is offline
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Default A/C issue - not blowing thru front vents

So, I did some searching but didn't find a posting with my particular issue, but I could have missed something. I have successfully managed to bring my brother's truck back from the dead (for those that read my intro when I registered here). However, not everything works right, which I expected.

The A/C had no cold air. One of the A/C techs where I work was kind enough to put a pound of freon into the system. This helped but he did not want to put too much in with the system not working correctly. Adjusting the blower settings does no good. I can adjust the fan speed, temp (cold to hot and back), on/off. But it makes no difference whether it is on Max, Normal, Vent, Defrost, etc., it only comes out through the defrost and floor vents.

I tore into the dash but could only get to the servo for the heat/cold blend door. I pulled the blower motor, which is working correctly, and cleaned out a wasp nest, dirt-dobber(?) nests, and assorted bugs and grass. So I was hoping that maybe I could get into other parts of the vent system, but so far have had no luck. And, short of total dash disassembly, I am at a loss.

Anyone have thoughts on other possible problems/fixes?
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Old 07-08-2011, 02:02 PM
FireRanger FireRanger is offline
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Default Re: A/C issue - not blowing thru front vents

Yes. You have a massive vacuum leak or the vacuum line to the HVAC selector is disconnected. The damper that controls the air flow is vacuum operated and a sprint returns it to a default of defrost only when vacuum is lost.
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  #3  
Old 07-08-2011, 02:19 PM
brotherstorm brotherstorm is offline
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Default Re: A/C issue - not blowing thru front vents

I checked the connections for the vacuum lines and everything is connected. I found no obvious issues with the lines themselves (breaks, splits, etc.). My guess at this point is an issue with what creates the vacuum for the A/C system, a line I can't see, or a break/split I can't see.
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Old 07-09-2011, 01:05 AM
Rg1Baja Rg1Baja is offline
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Default Re: A/C issue - not blowing thru front vents

Quote:
Originally Posted by brotherstorm View Post
My guess at this point is an issue with what creates the vacuum for the A/C system, a line I can't see, or a break/split I can't see.
You have a vacuum leak for sure somewhere.

----------

Do you have a vacuum guage you can put on there?
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  #5  
Old 07-09-2011, 03:30 AM
drppdyllwrngr drppdyllwrngr is offline
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Default Re: A/C issue - not blowing thru front vents

not sure what year you are working with, but there could/should be a black plastic sphere on the passenger side inner fender. it's a vacuum reservoir for the vents. if one of the vacuum lines or eve the sphere itself is damaged, the ac default is to defrost. it's common for a line to come off, so check there.
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Old 07-09-2011, 05:07 PM
brotherstorm brotherstorm is offline
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Default Re: A/C issue - not blowing thru front vents

Given the fact that this truck sat in my brother's front yard for 5 years unmoved and uncranked, I can only imagine what all else I will have to replace. I know that the A/C systems are somewhat fragile to begin with; seals, gaskets, valves, fittings, rusted lines, cracked or broken vacuum lines, etc.

I located the actuator for the air door and removed it. The actuator does not leak (depress plunger and hold finger on vacuum port - held in place). This also caused the door to close into the position I need it in. Now I just need to find the cause for the vacuum failure. Thank you for the additional information; gives me ANOTHER part to look for and probably replace.

The A/C/ tech that helped me previously mentioned the possibility that a valve in the heater lines could also be malfunctioning and not allowing the system to cut out the heat. The recharge definitely helped. The valve he mentioned has a vacuum line attached on the backside. So I am hoping that whatever the cause of my leak/failure is simply a part that can be replaced.

Again, thanks for the extra info!!!

BTW, my truck is a 2000 Ranger Sport, 2.5 I4, manual shift, regular cab, regular bed. The A/C and a CD player are the only extras that came with the truck.
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Old 07-09-2011, 06:08 PM
FireRanger FireRanger is offline
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Default Re: A/C issue - not blowing thru front vents

Find a new AC tech that knows what he is talking about. The blend door, which is working perfectly fine, shuts air flow to the heater core. It could be on fire and not effect the AC. The valve on the hot water line only closes in MAX AC and OFF.
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  #8  
Old 07-12-2011, 09:12 AM
brotherstorm brotherstorm is offline
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Default Re: A/C issue - not blowing thru front vents

Again, more useful info. It didn't make sense that that valve was the problem, but since there is a vacuum line on it... I was hoping that if it was the problem at least it would be easy to get at.

For now it is working the way I need it to. This will give me time to find the real issue.
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  #9  
Old 08-28-2011, 04:00 PM
brotherstorm brotherstorm is offline
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Default Re: A/C issue - not blowing thru front vents

So, I found at least one of my problems. Two vacuum lines had melted around the back of the EGR down tube; had to pry them off. Spliced the lines and I now have air coming out of the proper vents.

However, it still changes to defrost under hard accelleration (anyone have ideas on this?). I can turn the AC off then on and it works correct again. Max AC doesnt really do anything and the vent cuts out more often when I try to use it.

The AC still needs a recharge and I have one can of freon left, along with a can of AC system oil. As soon as I can get the recharge done, I will be doing a little better. 40+ days of triple digit heat is kicking my a**.
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  #10  
Old 08-28-2011, 04:47 PM
FireRanger FireRanger is offline
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Default Re: A/C issue - not blowing thru front vents

That's because essentially engine vacuum goes down with higher RPM. You still have a big leak somewhere.
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  #11  
Old 08-29-2011, 08:13 AM
sheltonfilms sheltonfilms is offline
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Default Re: A/C issue - not blowing thru front vents

^^ Yep still a vacuum leak. When mine did this it was a bad rubber diaphragm in the heater control valve. This only happened in max ac so which the heater control valve, recirculation door, and dash vents are part of this vacuum circuit.

See if this vid helps out any:

Note when I saw connected the vacuum gauge to the line I just disconnected that goes to the firewall, I don't mean connect to the line, but connect to the port that it was connected to on the vacuum canister.

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  #12  
Old 08-30-2011, 01:13 PM
brotherstorm brotherstorm is offline
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Default Re: A/C issue - not blowing thru front vents

My guess at this point would be the heater control valve; as I had no vacuum at the valve no matter what I did: normal AC, max AC, no AC, etc. I will check into replacing it next and see what happens. Tune in next week...or the week after, or the next...
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  #13  
Old 08-30-2011, 01:16 PM
sheltonfilms sheltonfilms is offline
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Default Re: A/C issue - not blowing thru front vents

Before you replace it explain "no vacuum at the valve"
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  #14  
Old 08-30-2011, 01:20 PM
FireRanger FireRanger is offline
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Default Re: A/C issue - not blowing thru front vents

You have no vacuum at the valve for the same reason there is no vacuum anywhere else in the HVAC system.... you have a big leak somewhere. If the valve was the problem you would have vacuum at the valve.

What Anthony meant was that the valve itself was what was leaking on his. If you unplug that vacuum line to check it and there is no vacuum in any setting, the problem isn't there. It is somewhere else.
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  #15  
Old 08-30-2011, 01:22 PM
sheltonfilms sheltonfilms is offline
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Default Re: A/C issue - not blowing thru front vents

Quote:
Originally Posted by FireRanger View Post
You have no vacuum at the valve for the same reason there is no vacuum anywhere else in the HVAC system.... you have a big leak somewhere. If the valve was the problem you would have vacuum at the valve.

What Anthony meant was that the valve itself was what was leaking on his. If you unplug that vacuum line to check it and there is no vacuum in any setting, the problem isn't there. It is somewhere else.
x2

Let me add that you should only have vacuum at the valve in the MAX A/C and OFF settings
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