Fogging Windshield / Vacuum Leak
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Le Mans Master
Joined: Mar 2006
Posts: 5,262
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From: E. Amherst NY
Fogging Windshield / Vacuum Leak
Toward the end of the season, I started having a problem with my windshield fogging up on occasion. I could barely see a little puff of air coming out of the vents, and then it would start fogging up. I thought about the heater core, but everything is nice and dry. I'm not losing any coolant that I can remember, and I check it pretty religiously.
On a potentially related note, at the beginning of the year, I couldn't get full force out of the vents for both A/C and heat. Which leads me to solving a bit of a vacuum leak in the system because it's not opening the doors all the way.
Could both of these problems be related?
On a potentially related note, at the beginning of the year, I couldn't get full force out of the vents for both A/C and heat. Which leads me to solving a bit of a vacuum leak in the system because it's not opening the doors all the way.
Could both of these problems be related?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Could be - you didn't post what Year, but find the HVAC vacuum source in the engine compartment and follow it to a 3 way cylindrical check valve - under or near the left fuel rail cover on the LT motors. Near the left side of the Distributor on the L98. That valve often breaks with age.
A small amount of Defrost is the Default with GM a/c. A leaking evaporator core can lead to fog though you can also get frost as a refrigerant at normal atmosphere's is about 32 below. If your a/c isn't blowing as cold as it once was, stop by an a/c shop and have them stick an electronic leak detector in your vents. A lot won't charge you anything since it takes all of 2 minutes.
A small amount of Defrost is the Default with GM a/c. A leaking evaporator core can lead to fog though you can also get frost as a refrigerant at normal atmosphere's is about 32 below. If your a/c isn't blowing as cold as it once was, stop by an a/c shop and have them stick an electronic leak detector in your vents. A lot won't charge you anything since it takes all of 2 minutes.
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
Could be - you didn't post what Year, but find the HVAC vacuum source in the engine compartment and follow it to a 3 way cylindrical check valve - under or near the left fuel rail cover on the LT motors. Near the left side of the Distributor on the L98. That valve often breaks with age.
A small amount of Defrost is the Default with GM a/c. A leaking evaporator core can lead to fog though you can also get frost as a refrigerant at normal atmosphere's is about 32 below. If your a/c isn't blowing as cold as it once was, stop by an a/c shop and have them stick an electronic leak detector in your vents. A lot won't charge you anything since it takes all of 2 minutes.
A small amount of Defrost is the Default with GM a/c. A leaking evaporator core can lead to fog though you can also get frost as a refrigerant at normal atmosphere's is about 32 below. If your a/c isn't blowing as cold as it once was, stop by an a/c shop and have them stick an electronic leak detector in your vents. A lot won't charge you anything since it takes all of 2 minutes.
any valve location advice for an '84?
Team Owner
Joined: Jan 2003
Posts: 20,324
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From: Summerland B.C. Canada
Oh, and if you don't wash that panel, your vette will smell like anti-freeze for a long time. Ask me how I know
