HVAC Vacuum Question
Thread Starter
Racer
Joined: May 2005
Posts: 439
Likes: 0
HVAC Vacuum Question
While I was under the hood, I took a vacuum tool and attached it to the HVAC vacuum line that goes under the condensor core/ blower motor housing and the tool would not get any vacuum, like the other end of the hose is open, can anybody tell me if this is normal, I mean shouldn't it hold vacuum, and at any setting on the AC head unit ?
If the hose is off, or I have a bad vacuum leak under the dash, could it cause an idle problem, any info on how the check ball under the plenum, HVAC vacuum lines, would be appreciated.
Thanks
If the hose is off, or I have a bad vacuum leak under the dash, could it cause an idle problem, any info on how the check ball under the plenum, HVAC vacuum lines, would be appreciated.
Thanks
Le Mans Master
Joined: Jul 2001
Posts: 8,184
Likes: 3
From: Santa Maria, CA
There should be only one vac line going to the HVAC controller. This vac line comes out of a fitting on the intake plenum of the motor, then a one way check valave. The line then goes into the harness loom, thru the firewall and into the passenger compartment to the controller mounted next to the steering column.
A leak in this line after the check valave will not affect the idle.
What year Vette? It's the electronic C68 system?
A leak in this line after the check valave will not affect the idle.
What year Vette? It's the electronic C68 system?
Thread Starter
Racer
Joined: May 2005
Posts: 439
Likes: 0
Originally Posted by 89 Paul in Cal
There should be only one vac line going to the HVAC controller. This vac line comes out of a fitting on the intake plenum of the motor, then a one way check valave. The line then goes into the harness loom, thru the firewall and into the passenger compartment to the controller mounted next to the steering column.
A leak in this line after the check valave will not affect the idle.
What year Vette? It's the electronic C68 system?
A leak in this line after the check valave will not affect the idle.
What year Vette? It's the electronic C68 system?
Seems like the vacuum hose going to the AC head unit from under the hood should hold a vacuum when I apply it under the hood with my vacuum pump tool, but it will not even try to hold a vacuum, like something under the dash is disconnected. I'm using my tool after the check valve. Question, does the check valve allow vacuum to this line when the intake is pulling vacuum or does it shut the vacuum line off when the intake is pulling vacuum, not sure how the check ball works.
Le Mans Master
Joined: Jul 2001
Posts: 8,184
Likes: 3
From: Santa Maria, CA
Hmmm...
on my L98, the check valve is between the rear of the intake and the firewall. Real easy to get to. It should allow vacuum to suck on the controller but not to blow it. Can easily be removed and check for operation.
The lines are old and brittle and possibly be cracked somewhere.
If I may ask, what is the original problem? Are you not getting A/C or heat or ?????
Here is a view of the controller:
on my L98, the check valve is between the rear of the intake and the firewall. Real easy to get to. It should allow vacuum to suck on the controller but not to blow it. Can easily be removed and check for operation.
The lines are old and brittle and possibly be cracked somewhere.
If I may ask, what is the original problem? Are you not getting A/C or heat or ?????
Here is a view of the controller:
Thread Starter
Racer
Joined: May 2005
Posts: 439
Likes: 0
Originally Posted by 89 Paul in Cal
Hmmm...
on my L98, the check valve is between the rear of the intake and the firewall. Real easy to get to. It should allow vacuum to suck on the controller but not to blow it. Can easily be removed and check for operation.
The lines are old and brittle and possibly be cracked somewhere.
If I may ask, what is the original problem? Are you not getting A/C or heat or ?????
Here is a view of the controller:
on my L98, the check valve is between the rear of the intake and the firewall. Real easy to get to. It should allow vacuum to suck on the controller but not to blow it. Can easily be removed and check for operation.
The lines are old and brittle and possibly be cracked somewhere.
If I may ask, what is the original problem? Are you not getting A/C or heat or ?????
Here is a view of the controller:
paul,
There is no suction on the check valve with the car idling, I can tell that anyway.
The original problem is my AC just doesn't seem to blow as hard as it should, it blows cold, but seems like it should blow harder.
So the line after the check valve going to the manifold should have suction ? ( it doesn't )
The line going to the AC head unit, should it hold a vacuum when I try to pull avacuum on it from under the hood, ( it doesn't - doesn't even try )
