Dash Air Vent (Defrost Vent) is Always on
#1
Dash Air Vent (Defrost Vent) is Always on
Hey everyone,
I am obviously new around here, but I have been lurking for a bit. I have a 98 and recently after having the trans repaired (the battery was disconnected) I had to retrain the Actuators for the A/C due to the vents on the d/s blowing hot while the p/s blew cold. I got this issue taken care of but I am now having another issue.
No matter what I do I cannot get the vent on the top of the dash (the defrost vent) to shut off. Even if I swith the HVAC Controls to floor only, it still comes through the Defrost vent as well.
Any ideas?? Thanks for the help in advance.
I am obviously new around here, but I have been lurking for a bit. I have a 98 and recently after having the trans repaired (the battery was disconnected) I had to retrain the Actuators for the A/C due to the vents on the d/s blowing hot while the p/s blew cold. I got this issue taken care of but I am now having another issue.
No matter what I do I cannot get the vent on the top of the dash (the defrost vent) to shut off. Even if I swith the HVAC Controls to floor only, it still comes through the Defrost vent as well.
Any ideas?? Thanks for the help in advance.
#2
Tech Contributor
Hey everyone,
I am obviously new around here, but I have been lurking for a bit. I have a 98 and recently after having the trans repaired (the battery was disconnected) I had to retrain the Actuators for the A/C due to the vents on the d/s blowing hot while the p/s blew cold. I got this issue taken care of but I am now having another issue.
No matter what I do I cannot get the vent on the top of the dash (the defrost vent) to shut off. Even if I swith the HVAC Controls to floor only, it still comes through the Defrost vent as well.
Any ideas?? Thanks for the help in advance.
I am obviously new around here, but I have been lurking for a bit. I have a 98 and recently after having the trans repaired (the battery was disconnected) I had to retrain the Actuators for the A/C due to the vents on the d/s blowing hot while the p/s blew cold. I got this issue taken care of but I am now having another issue.
No matter what I do I cannot get the vent on the top of the dash (the defrost vent) to shut off. Even if I swith the HVAC Controls to floor only, it still comes through the Defrost vent as well.
Any ideas?? Thanks for the help in advance.
#3
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
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CI 6,7,8,9,11 Vet
St. Jude Donor '08
All the HVAC damper doors are vacuum controled. Your missing the vacuum signal to that hvac head unit. It starts on the back of the intake manifold goes thru the main wiring harness to the pass fender well under the battery and thru the fire wall to the havac unit.
BC
BC
#4
Thanks guys, I will look into this as soon as I am not at work. And because I forgot to put it in my original post (which I can't believe I forgot)....there were no error codes. In fact this is the first time in a LONG while that I haven't even seen a Historical code come up.
Thanks again.
Thanks again.
#5
4th Gear
Member Since: Aug 2009
Location: Grapevine Texas
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Thanks guys, I will look into this as soon as I am not at work. And because I forgot to put it in my original post (which I can't believe I forgot)....there were no error codes. In fact this is the first time in a LONG while that I haven't even seen a Historical code come up.
Thanks again.
Thanks again.
#6
1st Gear
Member Since: Jul 2009
Location: Nashville Tennessee
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You will find all of the answers you need in this post:
http://forums.corvetteforum.com/c5-t...nge-vents.html
Trace the vacuum lines from behind the intake manifold, through the harness, under the battery, and to the vacuum canister (located in the passenger side wheel well behind the fender). Also trace the line going in through the firewall underneath the battery.
Don't be surprised if you find SEVERAL vacuum leaks. I fixed one leak in the line from the manifold only to find 2 more coming off the canister going into the firewall. I also discovered a crack in the checkvalve at the cannister.
I've heard some say that most of the vacuum line damage under the battery is from corrosion created by faulty OEM batteries that had a tendency to leak. I did find corrosion under my battery and cleaned, primed, and painted the area. Always best to swap out for a gel based battery (Optima, etc.)
AC is good and cold now with at least an 80% improvement. The air also goes where the 5 position control dictates. The interior vacuum valves that operate the system are large and easily heard when operating properly. No sound = no vacuum...
http://forums.corvetteforum.com/c5-t...nge-vents.html
Trace the vacuum lines from behind the intake manifold, through the harness, under the battery, and to the vacuum canister (located in the passenger side wheel well behind the fender). Also trace the line going in through the firewall underneath the battery.
Don't be surprised if you find SEVERAL vacuum leaks. I fixed one leak in the line from the manifold only to find 2 more coming off the canister going into the firewall. I also discovered a crack in the checkvalve at the cannister.
I've heard some say that most of the vacuum line damage under the battery is from corrosion created by faulty OEM batteries that had a tendency to leak. I did find corrosion under my battery and cleaned, primed, and painted the area. Always best to swap out for a gel based battery (Optima, etc.)
AC is good and cold now with at least an 80% improvement. The air also goes where the 5 position control dictates. The interior vacuum valves that operate the system are large and easily heard when operating properly. No sound = no vacuum...