Help! Heater Core Part 2 (aka Now What!)

[woodpuppy]

;help
Here's a link to my original thread;

http://www.corvetteactioncenter.com/forums/showthread.php?p=925055#post925055

This is a related item to my previous post, but still different enough I wanted to start a new thread.

I have a 1986 Coupe, L98, Automatic, with Electronic Climate Control.

When I purchased the Vette a few months ago the hoses to the heater core were disconnected which lead me to believe the heater core was bad.

I finally worked my way down my punchlist to #3 Heater Core Replacement. I came on to CAC and solicited advice in my previous post, purchased the heater core, coolant, thermostat, and all new hoses.

As I stood in the driveway surveying the task at hand I started to wonder if the heater core was actually bad or if the previous owner disconnected it for some unknown reason.

So I decided to drain the cooling system, replace the thermostat and all hoses, remove the homemade bypass contraption followed by a complete flush and refill with a 50/50 mix of coolant and water and 1 bottle of Royal Purple Purple Ice.

On the initial test drive (after idling in the drive for 20 minutes) I wasn't getting any real hot air from any vent, just kind of warm. But after 10 minutes of driving the air from the vents got really hot.

Numerous checks for leaks or a wet floorboard during the refill, test drive, and hour plus idling in the drive provided a good suprise; the heater core wasn't (still isn't) leaking. And now I have heat .
Now here's the new problem/challenge I can't get the air to cool back down. No matter which vent (defrost, heater, dash) the air comes out of it is all hot all the time now. I hear the doors opening and closing as I cycle through the various vent settings. When on defrost air only comes out the top of the dash, on heater via the under dash vents, dash vents on that setting, and both dash and under dash when on bi-level.

My ECC display has been tempermental since I purchased the car, but if I push a button what's supposed to happen happens I just don't have a digital display.

So there (here) I am pushing the cool button for the temp setting and it is staying hot.

A check of the A/C components under the hood show the lines and dryer (?big silver cylinder just behind the radiator on the passenger side) are very cold and the A/C compressor is spinning/engaging, but still no cool air coming from the vents.

Prior to putting the heater core "back in line" the AC was working great, blew hard and cold.

I've doubled, tripled, and Doubled Doubled checked all of my hose connections to make sure I have all of the cooling plumbing correct.

I am at a total loss here

Could the "cool" button on the ECC have died and the other buttons still work just fine? That seems to simple and coincidental, but not out of the realm of possibilites I guess.

Coolant temp is running between 190-200 degrees while idling and driving.

All air has been purged from the cooling system.

Coolant is at the proper level.

I disconnected the battery to "wipe" the system clean per se with the same results.

If you need more info please ask away.

Thanks in advance for any assistance, help, advice offered.

Jeff

 

[jmccloud]

Heater doorSSS

There are 2+ 'heater doors'.
One determines where the air comes out - yours appears to be working.
The other determines whether the air is cold or hot - yours is likely stuck.
Take the 'module' off of the fan housing (under the hood) and you can see the temperature door.
There's a connector from the actuator to the door that may be loose, the clip(s) that hold the connector may be broken or the actuator may be kaput.
You can likely see which by looking in the hole in the fan housing while a friend moves the temperature control from cold to hot.
A more remote possibility is that the ambient air temp sensor is shot. If it is, your display of outside temp will be in error. If that's the case, the ambient air sensor is on the passenger side of the radiator, down low. Not too $$$. Of course, the interior temp sensor could be shot. I don't know its location.
Hope this helps

 

[muddywaters]

The heater door thing is exactly what happened to my 88. I found the broken plastic clip on the pass. side floor. I took the module out and wedged the door against the heater core so I could get A/C in the summer time. I lay the car up for the winter so getting heat isn't an issue. I'll fix it when I have to. I still get some heat thru the tunnel, but when it gets real cold,it's parked.......

 

[woodpuppy]

Thanks for pointing me to a starting place for diagnosis. I was totally clueless. I'll let you know what I find.

 

[CorvetteArchives]

I'm not familiar with the ECC so this may not apply.....
But even with ECC shouldnt you still have a water valve assembly that controls flow of coolant to the core? It's vacuum operated.
looks like this:

 

[Hib Halverson]

In the opening thread, I didn't see any reference to service data.

Have you considered getting a Factory Service Manual and using the diagnostic information in the section on HVAC to help you solve the problems with your C68 A/C?

 

[woodpuppy]

I have a piece similar to the one in the picture and it appears to be working properly.

 

[woodpuppy]

You know a few weeks after I got the Vette I provided my wife the info for odering the factory manuals and told her I "needed" them. And then I forgot about it. So yesterday when this problem arised I went "huh I wonder where my manuals are the wife ordered for me?" So I asked the wife and she replied; "Oh you wanted me to order them?" Anyway they are ordered now.

 

[Hib Halverson]

I've never worked on an early C68 system, but when the one in my 95 got whacky as far as not being able to select various functions and so forth, I pulled the control head and cleaned all the buttons and switches. Solved all my problems.

I've seen posts on this and other forums about how to do that. I think I got my info from the ZR1 Net mail list...but I can't remember.

Also, it should be clear by now that the previous owner simply bypassed the heater because he/she didn't know how to fix the C68. Consider yourself lucky that, from a coolant leak standpoint, the hardware on that car seems ok. Good call on changing your coolant too, but, since you're in TX, you probably can go to less antifreeze and gain some cooling performance. Living in So. CA, I use no antifreeze at all in my Vettes and my daily-driver Camaro, just straight distilled water, couple bottles of Red Line Water Wetter (for its surfactants and anticorrosives) and coolant flushing ever 24-36 months.

 

[woodpuppy]

There are 2+ 'heater doors'.
One determines where the air comes out - yours appears to be working.
The other determines whether the air is cold or hot - yours is likely stuck.
Take the 'module' off of the fan housing (under the hood) and you can see the temperature door.
There's a connector from the actuator to the door that may be loose, the clip(s) that hold the connector may be broken or the actuator may be kaput.
You can likely see which by looking in the hole in the fan housing while a friend moves the temperature control from cold to hot.
A more remote possibility is that the ambient air temp sensor is shot. If it is, your display of outside temp will be in error. If that's the case, the ambient air sensor is on the passenger side of the radiator, down low. Not too $$$. Of course, the interior temp sensor could be shot. I don't know its location.
Hope this helps

I did as you suggested and removed the module and discovered that it's definitely a "door" issue.

So I got lucky on not having to change the heater core, but now I have to figure out how to access the door and fix it.

Oh well I didn't have any thing planned for the evening except handing out candy.

 

[woodpuppy]

Thanks for your input I really appreciate it. Yeah I've read several of the C68 post on CAC and have found a "guide" on how to troubleshoot, clean, and repair the ECC. It's actually on my punchlist to do right after replacing the heater core. Which thankfully doesn't look like I'll have to do now.

As for my current problem it appears to be a door issue. The door doesn't move when you use the controls and it just kind of flops around.

Which also explains why my A/C has been fickle since I got the car.

Any suggestions on how to access the door and fix it?

Thanks.

 

[woodpuppy]

I went ahead and "tore" into the dash controls for the ECC tonight. Amazingly simple. Gave everything a good cleaning and/or dusting and a dab of dielectric grease on the pins for all connections prior to reassembly.

And what do you know all buttons and lights now work as they should. I must say I really enjoyed looking down while driving and seeing the temp setting for the ECC or the exterior temp being constantly displayed.

Unfortunately it didn't help my controlled temp air flow issue.

So now it's back to fixing my temp control door issue.

 

[woodpuppy]

Fixed

Fixed this issue last week and the engine blew this weekend.:ugh

See my earlier post from today seeking advice and input on doing an engine swap.

The hits just keep on coming.

 

[1962BRT]

An old C4 Corvette Guru I know says that the C4 was built starting with the heater duct and then you build the car around it.

As far as access to the heater door, etc. With an inspection mirror, pick up tools, and a contortionist, you can access some of the stuff from the engine compartment side after removing as mush housing as you possibly can. It might be easier with the engine pulled.

The heater doors on my 86 are rusted in place due to a rodent family living in it before I got it. The heater blows out little bits of stuff all over the dash board all of the time.

 

[helphos]

AC woes

HIB- thanks for the tip on cleaning the parts you can get to. I have the same problem as the OP- temp door stuck in the 'heat' position. If your suggestion has a 10% chance of working it's worth trying.
Otherwise I'll do what the other guy's PO did- disconnect the hose to the heater and do without heat.

I ran the diagnostic suggested in the FSM and it id'd the the temp door, so taking the hot coolant away from the heater sounds like a 'bush league' but effective solution.