A/C Cool; not cold.
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Cross-Country
Joined: Apr 2006
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A/C Cool; not cold.
I have a '97 250 supercab. I bought the truck three years ago and the A/C was COLD! Last season I noticed that it was really only cool at the end of the summer. This year I had the A/C compressor serviced and the tech topped off the freon. It's still only cool. The pressure is right at 40 to 45 and there's always plenty of water dripping off the compressor when I shut the A/C down, but the air is only cool. It even seems to cycle from cool for a few minutes, to almost cool for a minute or so then back to cool. What can be causing this? Also, when the system is set to vent only, the air that comes in is fairly warm. It certainly seems warmer than the outside air. Any Suggestions? 
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Joined: Sep 2010
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Instal this bypass valve in the coolant lines that go into the firewall/heat core.
Buy Factory Air Valve 74809 at Advance Auto Parts____
Its vacuum controlled. So get some vacuum line and a Tee. Look under the passenger side dashboard. You see a vacuum actuator under there. Hook it up like the picture I have attached. See where the new vac line goes through the heaterbox? Right between the heater coolant lines? I drilled this from under the dash. My little rigid drill fit up there. Might be able to drill it from the top. With the vac lines hooked up like this the bypass valve will close when the HVAC control is set on "vent, a/c and mac a/c"
Buy Factory Air Valve 74809 at Advance Auto Parts____
Its vacuum controlled. So get some vacuum line and a Tee. Look under the passenger side dashboard. You see a vacuum actuator under there. Hook it up like the picture I have attached. See where the new vac line goes through the heaterbox? Right between the heater coolant lines? I drilled this from under the dash. My little rigid drill fit up there. Might be able to drill it from the top. With the vac lines hooked up like this the bypass valve will close when the HVAC control is set on "vent, a/c and mac a/c"
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Cross-Country
Joined: Apr 2006
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Thanks for the info and pics King7765. I'm still a little confused though. I'm not clear where the vac line is going in the heater box? What does it connect to? What is the picture of the vac line held together with the zip tie under the hood showing me? Can you please provide more detail? What causes the blend door to stick? Where is located? I appreciate all the help, I'm just trying to get it right before I start trying to repair it.
i ain't rite
Joined: Mar 2005
Posts: 65,453
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From: Marlboro Mental Hospital.
the blend door sticks from old age and deteriorating parts.
also, if the weatherstriping/gasket around the door fails, it will not seal and hot air from the heater will enter the plenum.
also, if the weatherstriping/gasket around the door fails, it will not seal and hot air from the heater will enter the plenum.
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Nicmike
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