2001 Chevy Astro Air Conditioner blows thru defroster only

Tiny
HAOSBORN
  • MEMBER
  • 2001 CHEVROLET ASTRO
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 89,000 MILES
Air Conditioner blows through defroster vent only
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Monday, October 27th, 2008 AT 4:09 PM

2 Replies

Tiny
JDL
  • EXPERT
Some of your hvac controls are vacuum operated, I'd check for vacuum source. It may default to the defrost mode if there is no vacuum. The engine is the source of vacuum, trace the vacuum line that goes through the firewall, under the hood, find a junction or tee, union, whatever for that line, take it loose, with the engine idling, check for vacuum on that line. If there is no vacuum, the problem is the vacuum source or line under the hood.
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Tuesday, October 28th, 2008 AT 10:55 AM
Tiny
TECHMAN1
  • MEMBER
There is a tiny 4 millimeter black plastic vacuum line that runs from (looking under the hood), just behind your air conditioner compressor on the top, right of center to the left, under the breather hose to the intake and on over to the left to the air conditioner evaporator body just behind your windshield washer and antifreeze reservoirs. This hose bakes and cracks with time. This vacuum line is easy to find. It is the only one like it under the hood. They always crack close to the air intake hose between the air filter and the intake. I have broken the split in 2 and spliced them with a one inch piece of weedeater fuel hose. After a few years, it splits open in other places. I then got some 6 millimeter air line plastic tubing, cut the 4 millimeter hose about 3 inches from the connector at each end, and then plugged the ends into the larger tubing and sealed them with RTV silicone.

By the way, there is a plastic, round vacuum canaster under the windshield washer fluid reservoir. The hose to that deteriorates also.

Ken
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Tuesday, October 28th, 2008 AT 9:39 PM

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