Vacuum source heater diverter valve '86
#1
Junior Member
Thread Starter
Join Date: Jul 2015
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
Car: '86 IROC Z28 W T tops
Engine: 305 TPI
Vacuum source heater diverter valve '86
Yep I searched the heck out if this...
All I can find is info that doesn't match my '86
So...
'86 IROC, 305 TPI w AC
Short...
Where does the vacuum line controlling the diverter valve come from??? It's NOT the hvac controls!!!
Long...
Previous owner tapped the heater diverter valve vacuum straight to the manifold. As such it's always closed (I think) . Not a problem at the moment, but in a just a few weeks Colorado weather can be "brisk" in the am.
Anyway... I've tried to addresses ALL the vacuum leaks both under the hood and under the dash and I really don't want to leave a vacuum line open just because I can't find it!
I'm guessing the hard line is broken off inside one of my mutilated wiring harness bundles and I can't spot it under the dash. Of course I don't know what I'm looking for either.
My '86 only has ONE bundle of vacuum lines at the hvac control NOT two as the later cars have. And, no, I'm not missing one. It was never there.
Make sense?
Thanks in advance
Eric
All I can find is info that doesn't match my '86
So...
'86 IROC, 305 TPI w AC
Short...
Where does the vacuum line controlling the diverter valve come from??? It's NOT the hvac controls!!!
Long...
Previous owner tapped the heater diverter valve vacuum straight to the manifold. As such it's always closed (I think) . Not a problem at the moment, but in a just a few weeks Colorado weather can be "brisk" in the am.
Anyway... I've tried to addresses ALL the vacuum leaks both under the hood and under the dash and I really don't want to leave a vacuum line open just because I can't find it!
I'm guessing the hard line is broken off inside one of my mutilated wiring harness bundles and I can't spot it under the dash. Of course I don't know what I'm looking for either.
My '86 only has ONE bundle of vacuum lines at the hvac control NOT two as the later cars have. And, no, I'm not missing one. It was never there.
Make sense?
Thanks in advance
Eric
Last edited by THX181; 08-05-2015 at 01:49 AM. Reason: Typo
#2
Supreme Member
iTrader: (7)
Join Date: May 2004
Location: Lexington, SC
Posts: 5,291
Likes: 0
Received 58 Likes
on
52 Posts
Car: 1987 SC/1985 TA
Engine: 350/vortec/fitech
Transmission: T56
Axle/Gears: 3.27 9-bolt
Re: Vacuum source heater diverter valve '86
Stock the line (thin, hard plastic) came out of the hvac harness. The ac control head switched vacuum on/off to it.
Your car has either had the control head swapped out for an earlier one (most likely) or has been otherwise fargled.
At this point if you've verified the vac switch does not exist on your particular control head I'd just remove the diverter valve. Early thirdgens didn't use them.
Another option is to find the correct control head. It will have to have the needed vac switch AND the AC ON rad fan switch.
Your car has either had the control head swapped out for an earlier one (most likely) or has been otherwise fargled.
At this point if you've verified the vac switch does not exist on your particular control head I'd just remove the diverter valve. Early thirdgens didn't use them.
Another option is to find the correct control head. It will have to have the needed vac switch AND the AC ON rad fan switch.
#3
Junior Member
Thread Starter
Join Date: Jul 2015
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
Car: '86 IROC Z28 W T tops
Engine: 305 TPI
Re: Vacuum source heater diverter valve '86
Well that explains why the parts catalog doesn't actually list the valve for an '86.
So, how, exactly, does the heater valve in an 86 work?
So, how, exactly, does the heater valve in an 86 work?
#4
Supreme Member
iTrader: (7)
Join Date: May 2004
Location: Lexington, SC
Posts: 5,291
Likes: 0
Received 58 Likes
on
52 Posts
Car: 1987 SC/1985 TA
Engine: 350/vortec/fitech
Transmission: T56
Axle/Gears: 3.27 9-bolt
Re: Vacuum source heater diverter valve '86
Vacuum closes the valve and stops the flow of hot water thru the heater core. Under AC operations this reportedly results in slightly lower air temps.
I know the valve was installed on 87s and not on 85s.
I know the valve was installed on 87s and not on 85s.
Thread
Thread Starter
Forum
Replies
Last Post
1992 Trans Am
History / Originality
27
05-10-2023 07:19 PM