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1994.5 - 1997 7.3L Power Stroke Diesel  

AC "Max" won't. . .

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Old Aug 26, 2007 | 10:18 AM
  #1  
WayneH's Avatar
WayneH
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AC "Max" won't. . .

I understand about the AC setting and the Max setting. For a while now the Max won't work. There is either a vacuum line or a baffle not working. Any thoughts? Hopefully I won't have to be a contortionist to fix it.

The AC works and all other settings work.

Thanks,

Wayne
 
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Old Aug 26, 2007 | 10:32 AM
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Neal 97 250
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Do you mean the max a/c won't work at all or is it just not cooling or not blowing on this setting?
 
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Old Aug 26, 2007 | 10:33 AM
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Neal 97 250
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The only real difference between regular and max settings is that max recirculates the air from inside and the regular is pulling fresh air from outside.
 
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Old Aug 26, 2007 | 10:35 AM
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Sorry,

The blower works. But on Max setting the interior air is recurculated rather than fresh air brought in. When you change the selector from AC to Max there is a definate noise level, or used to be. It's not there. The system stays on the AC setting.
 
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Old Aug 26, 2007 | 10:58 AM
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Neal 97 250
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Max should be recircing and should sound a little different because of that. If it doesn't sound different the flapper that shuts off outside air may be malfunctioning.
 
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Old Aug 26, 2007 | 11:04 AM
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Yes, either the baffle/flapper or a vacuum line that controls it. I'm wondering how to check it/fix it.
 
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Old Aug 26, 2007 | 11:27 AM
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97REDPSD
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From: texas
ck the white vacuum line its under hood by the evap case.
 
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Old Aug 26, 2007 | 12:08 PM
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Take a look here:
https://www.ford-trucks.com/forums/6...wer-speed.html
 
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Old Aug 26, 2007 | 12:09 PM
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Excellent,

I had noticed that line was cracked and crumbling. I cut out that part and slipped a slightly larger diameter plastic hose over the ends and secured it with tie wraps. There may be another spot.

Thanks.
 
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Old Aug 26, 2007 | 12:12 PM
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Cuda_jim. . .

Excellent also, thanks!
 
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Old Aug 26, 2007 | 01:41 PM
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My '97 is doing the same thing. On regular AC it blows mostly through the vents but some through the defroster. On Max/AC it blows all through the defroster. I figured it's a vacuum issue but haven't checked it out yet. It started a couple of days ago, a day after the gauges were installed.
 
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Old Aug 26, 2007 | 04:33 PM
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It was the white vacuum line. . .

When I repaired it last time it had a leak. Re-secured it and it's fixed. Later on I'll replace it.

Thanks loads guys,

Wayne
 
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Old Aug 26, 2007 | 06:29 PM
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From: Asheville
Mine was blowing on max and none on the other settings. They said that they replaced the blower motor resistor. Now it works. $120 parts and labor
 
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