Heater Trouble

[John H.]

Hello all,
I am having issues with my heater on my 85 GTS.
It doesn't work! When I turn it on, all I get is air, not hot or cold, just air?
I haven't had to use it in a very long time, in fact, I haven't ever really had to use it. I need to figure this out so that I can change my radiator+hoses.
I've already messed with the heater valve located on the firewall just about a million times, and my hot/cold (climate control) switch is broken btw.
What can I do to get it working again?
Thanks in advanced everyone!

-John

[allencr]

What can I do to get it working again?

ahh, fix was doesn't work?
Coolant flow thru the piping, valve & heater core and/or air flow thru the heater core. That's all of it except the electrical fan.

[ga_goosh]

try going to the car wash with the heater hoses off if possible. then spray the high pressure through your heater core. this should push out any debris that may have gotten trapped in the core over time. it might help to get that hot air. also when doing this make sure you take extra care with the heater core inlet and outlet as it could damage the heater core if your not careful.

[Red]

"and my hot/cold (climate control) switch is broken btw. "
Well, that's enough to kill it right there. That's a mechanical cable and it shifts the heater control valve on/off, or moves the plenum flap (I'm not sure which cable you've lost) either way, you need to drop the glove box, pull the radio surround, etc. and get in there to see what's broken and fix it.

I'd go more conservative on testing the heater core, disconnect the heater hoses under the hood and just use a garden hose to see if water can flow through the heater core. If it does, the control is your only problem. If the core is blocked and you get no flow, try to blow it out (reverse flow) but expect to need a new core. And if you park where leaves or grass clippings get blown onto the hood, they can get into the heater plenum and pack it up with crud. Once that happens things start to get blocked or rot out but if you have air blowing, that shouldn't be a worry.

Broken control cable: That could be all it takes.

[John H.]

Damn! You guys are awesome, thanks!
Yes, my climate control switch is broken, but I have done some research and I know that the
switch connects to the valve control on the firewall. I have already ripped out my glove
compartment and all the other pieces necessary to get back to that cable. I have also already
played with the control valve on the firewall (as stated) just about a million times. nothing
But my car used to be parked under trees at work so I will try what you guys suggested and try to
shoot some water through there.
I am suspecting that I need a new heater core, but I am one of those dudes that likes to double check, and
triple check if need be.
Thanks again guys, I totally appreciate it!

-John

[BlackStar]

Finding a heater core is hard to find. I had the same trouble too. The one i bought from autozone doesn't fit in the box at all. What I would do? First, skirt the heater control valve in the engine bay with WD40, and see if you can move it back and forth by hand. If you can free that up, then I would go back into the car. On my controls, the heater cable decided to not to move back and forth, and eventually the plastic that hold the cable to the control switch broke.

I took off the cable (its blue), and sprayed as much WD 40 as i could on both end, and moved the cable back and forth through its plastic surround. Once I got it moving, I still had a problem. The cable was held down in the engine bay, but not on the control switch. I got gehtto. I got a nut that would screw on securely onto the cable. On the control switch, there is a squared off section right after the place where the cable would normally be held down. I git my hack job in that area, and used two zip-ties in a cross pattern. It's holding up pretty well.

Or just get another HVAC control panel that is broken. Also. unplug the hoses that connect to your heater core. Poor in some white vinegar, and let it sit overnight. Next day, rinse it out with some hose water. I cleaned a lot of derbies out of the used one i bought.

[Red]

John-
Just to be clear, if crud got into the plenum box, the only ways water can clean it out are by running out the AC rain (a short hose that you can't see well, goes out the box, through the firewall, straight down maybe 4" and that's all) or by the heater floor vents, so any water that does get in my crop the crud where you don't want it.
The shops use a can of "shaving cream" that squirts UP the drain hose, supposedly dissolves crud and drains back out the same way.
Whatever you do, is you get water in the box, make sure it drains and dries thoroughly so you don't have a mildew problem.

[John H.]

Thanks for all of the help gents, I found this dude's write-up on his heater core issues http://www.dreamsofdrifting.com/ae86/heater/
I think when I get some time I will go ahead and try his method.
This is probably a stupid question but... will I have to drain my cooling system before I try and take out my heater core+heater hoses?
Thanks again guys!

[Red]

Well, you don't have to drain it, but if you do you are less likely to have koi pond in the car.<G>

You can probably disconnect the hoses (in front of the firewall) and blow out the heater core if you don't want to drain the whole thing. Or just drain it, and run on plain water in the meantime if you need to. When you finally do refill it, the system only needs about 2 gallons, either of premix or one gallon of AF and one gallon of distilled or deionized water, about $2-5/gallon in the supermarket. Over the long term, using tap water causes problems. For a week or month, no big deal.

[mikeyee]

the switches on the blower/heater vent thing might've gone to sh*t and aren't working. i'd look into that and disconnecting the wire/bendable coffee straw switch things and playing with them manually. a few friends had this issue and I jammed my hand back there and was able to get the heater vent to open up to allow the hot air through the in cabin vents.

hopefully this works, goodluck.

[John H.]

Thanks again for all the help guys. I am just waiting on some parts to arrive (and some free time ) to start working on it again!
I will let you all know how it goes!

-John