Whats up everyone. I decided to finally install a heater control valve in my car. Ive been suspecting that not having the valve was causing my a/c to not work efficiently. My 87 came with a valve, but my 86 didnt. I put the HVAC controls and associated harness/hoses from my 87 into m 86, with the idea that Ide install a valve some day. The LS1 circulates coolant through the heater core all the time. They dont have heater control valves. I never found a clear cut answer about the LS1 heater hose outputs on the water pump. Some say you can just block the flow off from them, some say the coolant has to circulate. SO I needed to find a valve that would allow that to happen. This is what I came up with. When the temp slider is over on the hot side, the vac line going to the heater control valve is dead. No vac. The coolant flows through the valve like it wasnt there. When the slider moves over to the cold side, vacuum is applied to the line, and the valve switches so that coolant goes in and comes out on the same side. The heater core side just sort of stops. Some coolant will still squeak by, but the majority will not. I felt the hoses, and the hoses after the valve do cool down compared to before...so its working. That cools down the heater core, thus cooling down the HVAC box area, thus making the air cooler as it goes through. It seems to work. I topped off my system with a can of 134, and now it blows very VERY cold. Just like it did in the 4th gen donor car before I took it apart. Im going to try it tomorrow on my drive home from work since it'll be hot. Just an FYI to those of you looking for a good option. The valve is from a newer full sized chevy van...but all you need is the part numbers I gave you. It fits really good. Thats it... not a big deal, but I dont remember seeing a heater control valve solution detailed anywhere. Any questions? J.

Just for fun...

http://www.youtube.com/watch?v=yKN14bJEDmc

J.

couldn't you use the stock 3rd gen heater control valve?

I forget why I didnt think I could use it. I think when the valve was activated, it didnt allow the coolant to re-circulate like it needed to for the LS1. Also, the hoses come off at different angles, not inline like that.

I dont have one to check to see how it operates though. I just seem to remember it not working how I needed it to.

This is cleaner since it really just splices into the hoses and keeps them inline. And its slimmer than the stock thirdgen...without the wider diaphram housing on top. I think it was $12 or something like that.

J.

looks a lot cleaner than my current setup. Might have to look into that

-jason

I think that was the main reason...its a pretty clean valve. Tucks nicely over to the side, and is pretty slim overall. I have to get a 90* rubber elbow for the vacuum connection so I can lay the vac line down more.

This morning I had my temp set to cold for most of the ride to work. I decided I wanted some heat, so I slid it over to hot. I had been driving for like 30 minutes, so by now, the heater core would have been hot. It took about a minute to get hot air out of it. That means the valve is working...since the core was cool and took awhile to blow hot.

This also makes "vents" blow cooler if you put the temp on cold. You get more of an ambient temp air...except for the heat it picks up on the way in.

So far, so good.

J.

After looking at your pics again, I think I am going to try this.

I run that stove pipe, and I am pretty sure its letting hot coolant into the heater core.... Gotta stop that. I need all the AC I can get down here! LOL

thanks for the write up!

-jason

Smart minds think alike...


I'm using a NAPA replacement for the stock thirdgen valve. I had to use a 90* hose to hook up to one side, as it does exit kindof odd. But - it can fit and work. We'll see how well the A/C lines fit now though...

Ok, can you post up a part number for the hoses, or at least a year, make, model for those of us that don't have a friendly parts place.

I'd like to get mine going next week if possible

thanks

-jason

if it helps any - the only place I've ever had any luck getting hoses with 90s is NAPA. I'll drive 30 extra minutes just to avoid AutoZone and O'Reilly's.

on your hvac controllers where does this vaccum go to or where does it come from?
i know purple is the main intake vaccum does this run into the gray one ? back to the heater control valve ?

Its 100% how it was on the stock thirdgen control set up...assuming the car had a heater control valve. My 86 didnt have one.

So here are some pictures to maybe shed some light on things.

Here are the stock 86 controls.


Here are the 87 controls. Notice the extra piece in the upper left hand corner of the unit. This is the "switch" for the heater control valve.




The units are otherwise identical.


I THINK...not positive...that the purple hose is the vac feed for the system. In other words, you hook the hard line to the intake, and that is where the purple hose gets its vac. Then...on the heater control units, the purple hose is t'd off to go to the vac switch. On the other side of the switch, is the grey hose. That hose is dead when the temp is set to hot. When you switch to cold, vac goes from the system feed hose (purple) to the grey hose...which in turn goes out to the valve.



The other end of the purple/grey hoses coming off that vac switch.


Cont'd...

It hooks to the hard plastic lines via a connector that can only go one way.



Finally...here is how the controls look with all the hoses and wires hooked up. I swapped the vac switch into the 86 control unit...because the 86's controls were super clean and tight and new looking. Then I used all the wiring and hoses from my 87, since I had the wiring changed for the LS1 system.



Thats the basic jist of it. Clear as mud?

J.

P.S....being able to only link 5 pictures in a post is really annoying..haha.

Thought I would add in some hose part numbers since I went out today to start this swap.

I bought two hoses at Advance Auto parts (Part #80405CS). I did have to trim 2" off the 'short' side to tuck them in where I wanted them. I will post pics once the car is more together. Right now its in 'mock up' stage.

Hope that helps others do this swap!

ok, grabbed another hose that is the correct size for the larger fitting

80416cs

pics to follow once I trim everything down to size.

Ok, got my install wrapped up and am a lot happier with it......

Not a bad idea to have 90's coming off the valve. My 90* ends are up at the heater core, and it still seemed to flow pretty well by just putting the valve right in the middle of them.

Now that Im working at autozone again...Im going to root through the hose isle when its time to redo things, assuming Im still working there for extra cash. That is...if I dont ditch my A/C. If I do, I wont need the heater control valve anymore and will probably ditch it and run hardlines from the heater core to the pump.

Looks good Jay!

J.

So did you use one of each of those numbers for each side of the vac control unit? or did you use 4 of the "larger", 80416cs?

some really good info, may add this later on once i get some of the other swap bugs worked out

I bought two of each hose.

Then trimmed them to fit the way I wanted.

I used the 90's off the heater core to get the valve on the strut tower

Then used the 90's to get down to the water pump (obviously).

I am really happy with how it turned out and it works great... got the car running today.