A/C vent barely blowing out air

1997 CHEVROLET CHEYENNE
278,000 MILES • 6 CYL • 2WD • AUTOMATIC
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FUNHAYDEN
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The A/C works and blows great in town, but when I take it on the highway, after about fifteen minutes there is barely anything blowing out of the vents even on high. It does not matter what setting it just barely blows anything out. What does barely come out of the vents is cold but it is not enough especially on a hot day. Can you tell me what is wrong and what I can do to fix it? Thank you.
Apr 19, 2018 at 11:50 AM
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ASEMASTER6371
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Good afternoon.

Could be a couple of things.

1. AC system freezing up. if the pressures are not correct, the evaporator will ice up blocking the flow of air. you need a set of gauges to check this and see. check to see if it is expelling water from the system.

2. HVAC air filter becoming clogged with moisture. When was the last time you had the filter changed?

Roy
Apr 19, 2018 at 12:43 PM
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FUNHAYDEN
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Thank you for your response. I will start by checking the HVAC filter. I bought this truck recently so I do not know when the last time it was changed.
Apr 19, 2018 at 12:49 PM
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ASEMASTER6371
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Okay, just looking on Alldata and it may or may not have a filter. it shows if you have it to be behind the glove box. there will be a cover with two screws you remove and just pull it out.

Roy
Apr 19, 2018 at 12:57 PM
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FUNHAYDEN
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Thank you.
Apr 19, 2018 at 12:59 PM
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ASEMASTER6371
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anytime. we are here and glad to help.

Roy
Apr 19, 2018 at 1:04 PM