|
|
1991 Chevy Caprice 5.0L - A/C Controls Question
|
|
|
| |
|
|
WyrTwister
User
Jul 15, 2014, 3:44 PM
Post #1 of 17
(2739 views)
|
|
1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
I am in the slow process of restoring this car ( belonged to my late Father ) . The A/C is one of those chores .
The controls have a bottom lever that goes from cool to heat . I think this has a mechanical cable that operates a blend door ?
There is a vacuum operated " hot coolant " valve , under the hood . I am guessing it is also operated by the bottom lever ?
Looking at a diagram of the control unit shows a double hose that , if I recall , is labeled as going to a water valve .
When I move the bottom lever , I hear a noise that sounds like it may be a blend door opening and closing . So , at least the blend door may be working correctly .
There is also an upper lever on the control unit that goes from max A/C on the left to defrost on the right . It seems , no matter what position that lever is in , part of the air is coming out the defrost vent & part coming out the dash A/C vents . Some may also be coming out the bottom heater vent ? Have not checked .
So , this control is not working properly .
The diagram of the control unit shows a 5 hose connection , which I figure are 5 vacuum hoses ?
Before I start messing inside and under the dash , I wish to verify that I truly do have good vacuum going to the control unit . Does anyone have a drawing / diagram if the vacuum system for this car ? And I would appreciate info on where the source vacuum line for the A/C controls , plug in to receive engine vacuum ?
Any other info or tips would be much appreciated . :-)
Thanks ,
Wyr
God bless
Read more: (no links allowed please)
(This post was edited by Tom Greenleaf on Jul 15, 2014, 8:49 PM)
|
|
| |
|
|
Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 15, 2014, 9:34 PM
Post #2 of 17
(2712 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
Wyr - Please no links except your own pics as needed but another forum! Try going to Burger King and asking for a Big Mac?
Any good info down right now for some reason. As they go this car should be easier. The heater control valve inline with heater hose shows three hose hook ups to it. I'll guess that it maintains flow going to back of engine as a bypass hose and limits how much hot coolant get to heater core and probably fine if not leaking.
Vacuum controls. High chances are ONE line goes into the car thru firewall area on passenger's side again a probably a black (likely) plastic vacuum hose easily broken and can be fixed with small vacuum hose if found leaking or broken. Diagrams for all that not available to me and not posted under the hood TMK for climate control things. You must know that is working and should come from a vacuum storage ball (plastic softball size thing) either hidden or obvious also on passenger's side (likely) under hood even down behind headlight possible?
Mix of vacuum controls and a cable. You get air out floor vents all the time so yes it's confused or getting no vacuum which more often gives you only defrost ducts if vacuum actuated.
Not much point in checking for much broken in dash till you know it gets vacuum properly for air flow controls. When that is known good then we can move on what and where to check.
A handy tool to have is a hand vacuum pump w gauge for this and more not all that costly. This is a fav of mine like this.....
 May not show just ask at parts store by description if not.
Be care and ready to fix or replace vacuum hoses and elbows anywhere at this age. Any vacuum trees of plastic try to cut hose off rather than pull as that plastic doesn't glue up well if you break those if found and need to fix or work with them.
The other thing if general things here and there are needed is to find a good pick your own salvage yard that has cars this old still for assorted things I doubt you'll find new.
If you need tons of specific data and diagrams get the AllDataDIY manual for it to have at your beck at call,
T
(This post was edited by Tom Greenleaf on Jul 15, 2014, 9:39 PM)
|
|
| |
|
|
Hammer Time
Ultimate Carjunky
/ Moderator
Jul 15, 2014, 10:23 PM
Post #3 of 17
(2702 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
See TSB#Number: 91-29-1B for a known problem about the temp cable mounting breaking also.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
|
|
| |
|
|
WyrTwister
User
Jul 15, 2014, 10:29 PM
Post #4 of 17
(2696 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
I will try to print these out and study them .
Thanks , :-)
Wyr
God bless
|
|
| |
|
|
Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 16, 2014, 12:39 AM
Post #5 of 17
(2687 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
That's as good as it gets from Hammer Time but hard in my view to read - my problem. What I do see is the control panel as you move it like expected is channeling vacuum to the assorted vacuum items to move them. Said in my novel it needs to have vacuum first then know if it works or not. That type can wear from being changed a lot over time and use and hiss right there. No known fix except another to me. I'm talking right at and behind the controls head itself.
This is where you may need a good parts source. Arggh - then wonder if used is any good too until you install it.
Do see if you can print those diagrams and have on hand. If with vacuum there as I recall you'll hear some hissing just changing modes then stop. If not it's leaking and go from there,
T
|
|
| |
|
|
Hammer Time
Ultimate Carjunky
/ Moderator
Jul 16, 2014, 3:41 AM
Post #6 of 17
(2680 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
These things used to have a rotary vacuum valve on the control head that used to go all the time. I don't know if it was used on that year.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
|
|
| |
|
|
Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 16, 2014, 4:00 AM
Post #7 of 17
(2676 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
Best guess is this is it 90>93 models. Nylon to nylon vacuum holes would line up with constant vacuum if available for the functions. White greased and if owner/driver constantly shut everything to OFF position or messed with them a lot the failed fast but hissing was heard for a while and still worked for a while. Limited vacuum volume so all goes nuts if one leaks too much is what I encountered just once, T
|
|
| |
|
|
WyrTwister
User
Jul 17, 2014, 1:56 AM
Post #8 of 17
(2649 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
I found a short piece of hose , under the hood , that looked " tired " . Replaced that , but , no joy. Also , in that line was a device ( under the hood ) hat I did not know its function.
Research this AM seems to indicate it nay be a check valve. Hope to investigate that this PM .
God bless
Wyr
|
|
| |
|
|
Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 17, 2014, 2:26 AM
Post #9 of 17
(2643 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
Check valves: Could be and if you can remove it should be marked with an arrow. If clean enough just blow thru it and will only go one way. If check valve for you dash vacuum controlled items fails most will default to defrost when engine is under load and return to where they were. A wide open leak they would be able to operate in the first place,
T
|
|
| |
|
|
Hammer Time
Ultimate Carjunky
/ Moderator
Jul 17, 2014, 4:09 AM
Post #10 of 17
(2639 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
You don't find these problems by just pecking and hunting around. You have to use a vacuum gauge and systematically measure the vacuum first coming into the switch and then back out on the appropriate hose for the mode was selected. Then you can determine where the problem is occurring.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
|
|
| |
|
|
WyrTwister
User
Jul 17, 2014, 5:25 AM
Post #11 of 17
(2629 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
I have not got to the switch yet . I started at the vacuum source . With what I think is the correct line , going to the A/C controls . Not certain yet , it is bundled with a big harness of wires headed towards the fire wall . It has a check valve , close to the throttle body . I verified the check valve is OK .
But , you are right . Pretty much the next step is to investigate under the dash .
God bless
Wyr
(This post was edited by WyrTwister on Jul 17, 2014, 11:35 AM)
|
|
| |
|
|
WyrTwister
User
Jul 17, 2014, 11:55 AM
Post #13 of 17
(2609 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
http://s719.photobucket.com/user/WyrTwister/media/vacuum_zps20e32edd.jpg.html
I have found these parts , up to the connector # 81 . Stopped to eat supper .
Will go back to it and see if I can figure out how to further take the dash apart , to reveal more of the vacuum system .
Pretty sure the correct vacuum hose is in the bundle / harness of wires , that pass through the fire wall at a common point .
The connector #81 comes apart . At this point , it seems there is no vacuum at the connector . But that is not conclusive , yet .
God bless
Wyr
|
|
| |
|
|
Hammer Time
Ultimate Carjunky
/ Moderator
Jul 17, 2014, 12:00 PM
Post #14 of 17
(2604 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
I don't know what you are using that coloring book for. I gave you a far better and more accurate diagram than that.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
|
|
| |
|
|
WyrTwister
User
Jul 17, 2014, 1:16 PM
Post #15 of 17
(2598 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
It shows the hose coming off the TB , the check valve , the hose going through a grommet in the fire wall and the connector . All of which I have located , one step at a time . Giving me confidence I am tracing the correct vacuum hose .
When I get further into the dash , I suspect your drawing will come unto its own .
Went to autozone and bought some small hose , smaller than I currently had . Still chasing ghosts .
To be continued .
God bless
Wyr
|
|
| |
|
|
Hammer Time
Ultimate Carjunky
/ Moderator
Jul 17, 2014, 1:21 PM
Post #16 of 17
(2597 views)
|
|
Re: 1991 Chevy Caprice 5.0L - A/C Controls Question
|
Sign In
|
|
You can do most of your checks at the control head. Measure the incoming vacuum on the black hose and if that matches manifold vacuum, you can start testing the output lines from the control head individually.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
|
|
| |
|
Auto Repair Home
SEARCH
WHO'S 
LOG 
2006 Toyoto Camry XLE Driver Side Electric Window Trouble
Tierod end change caused some kind of leak
Grounding Cable, 2017 Jeep Renegade Trailhawk
equipment
Howdy
