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Alright, I've learned to admit my ignorance when I cannot figure something out. I've read the FSM with absolutely no real description of how the vacuum actuated HVAC blend doors work. More specifically, how the vacuum is generated. I'm restoring my 89 and have the the car pretty bare on the interior. I made the commitment to learn each system as I go through, not only for future maintenance, but for personal knowledge.
I restored all the HVAC components except for the vacuum module that sits on the firewall, it was in great shape. From looking at other pics of those vacuum modules, I don't understand how that module generates vacuum to actuate the vacuum actuators for the various blend doors. I had assumed there would be some engine vac input, and after tracing all lines, I do not see where there is any passthrough for engine vacuum or input for vacuum. Am I way off in my thinking? I come to the fountain of information humble
There is a 3 way vacuum fitting sticking out the back of the driver side of the manifold. It provides vacuum to the cruise control, hvac and even continues to the front of the car. It branches out along the way.
There is a vacuum line coming out of the engine harness behind the distributor that connects to it. It's using engine vacuum.
Originally Posted by topfuel67
There is a 3 way vacuum fitting sticking out the back of the driver side of the manifold. It provides vacuum to the cruise control, hvac and even continues to the front of the car. It branches out along the way.
I only have two vacuum nips that come out on the passenger side of the upper plenum. One runs to the FPR, the other crosses over and feeds the cruise and then down to the evap canister spaghetti. Only other vac feed I have is for the driver side PCV. Have I completely missed something?
Aight...blonde move again. Found a vac diagram that shows that back second vac nipple should split off and feed the HVAC and the cruise. PO had the engine rebuilt and obviously they did it wrong. Bubba work strikes again. I’ll have to pop open the harness and find that vac line and re-do the fittings.
Solves two mysteries actually. I have spent the past two weeks cleaning up water leaks since the whole interior is out. I kept finding this tiny drip by the soon to be replaced check valve in the interior. I assume now the cut vac line on the engine bay side was channeling water through it into the car. Man I want to slap shitty mechanics
It took me a while to find mine. It's hard to get to in the harness and looks just like a black wire, about the same diameter. They get brittle with age.
It took me a while to find mine. It's hard to get to in the harness and looks just like a black wire, about the same diameter. They get brittle with age.
I was just about to post back and say exactly that. I got out there tonight and tracked it down. Sure enough, buried in the engine side harness, there was about a foot of that vac line with a broken end. About to order some check valves, new tubing, and a good 6 pack for this weekends projects
I am 6 years (lazy,lack of funds) into a 59k mile '89 with the EElectronic
(C68?) climate control.I paid "Fuel Injection Specialties" $2200 to replicate
my old brittle harness.It has the air line.The harness is a thing of beauty
I was just about to post back and say exactly that. I got out there tonight and tracked it down. Sure enough, buried in the engine side harness, there was about a foot of that vac line with a broken end. About to order some check valves, new tubing, and a good 6 pack for this weekends projects
I'm quite surprised you didn't stumble upon this thread with the same issue you had with some snapshots and FSM images. Late now but would have. You do NOT want to open that pass through
I'm quite surprised you didn't stumble upon this thread with the same issue you had with some snapshots and FSM images. Late now but would have. You do NOT want to open that pass through
Thanks for the links. Sometimes I search and search the site and cant seem to find things others do. I ended up stumbling on these after I put the post out
you can get a piece of rubber vac hose and splice it in. like this.
Thank you for posting this, I was going to hit the store today for some fittings, I like the way you did this better. Since the tube is 5/32, did you use a slightly smaller size tube/fitting or did you join it with a little silicone adhesive? I had a little 5/32 vac line left over from other projects and it doesn't quite seal nice to it. Also, did you run a check valve on the line as well?
I was just about to post back and say exactly that. I got out there tonight and tracked it down. Sure enough, buried in the engine side harness, there was about a foot of that vac line with a broken end. About to order some check valves, new tubing, and a good 6 pack for this weekends projects
now that you got your feet wet in C4 vacuum system, try fixing an early C3 headlight & wiper door system. You'll need a 6 pack of JD for that......trust me.
now that you got your feet wet in C4 vacuum system, try fixing an early C3 headlight & wiper door system. You'll need a 6 pack of JD for that......trust me.
I've got enough gremlins on mine to earn that 6 pack of JD
Originally Posted by VikingTrad3r
[left]looks like 5/32 ID rubber vac line. sorry no print on hose.
i put a dollap of contact cement for both lube and glue. it fit good and tight. had to push it in.
Awesome, I appreciate that. 5/32 it will be! Once I track down this FP wiring gremlin, I can get back to the HVAC...
Educate me, 1989 automatic HVAC
