My 77 arrived today. I cant get the heater to work. Moving the contols to any position doesn't seem to do anything, am I doing something wrong. Also the brake light is on with the park brake off, I dont have a manual yet so I was wondering if anyone has an idea what might be causing the light to stay on.

 

Is the blower motor running when you select low, med, or high speed?
If not, you could have a bad motor. Or, it could be more simple like a switch, wiring, or bad fuse.

Is the Master Cylinder resovoir filled?
Low fluid could be the problem. If you have low fluid, you may have a caliper leak (a VERY common problem with these cars), or a Master Cylinder leak. You may have to pull the wheels off to get a good look at the calipers. If the fluid looks OK, try pumping the pedal pretty hard several times and see if the light goes out. I think that is an indication of a bad MC.

Good Luck.

 

There are three components to the heater head unit under the dash. One component controlls vacuum that directs the air to the various vents, the other is electrical that controls the fan speed and the third is mechanical that controls the heater mixer door.

You need to be more specific on your problem, no hot air, no air movement or air not changing from defrost, vent and heater.

Bob

 

Mine did not work either..Turned out that the heater core was bad and they had just By-passed it.........So I had to install a new core and hook everything back up....Not much fun in an A/C car... :mad

 

Hi Bob
There isnt any airflow at any position. I don't hear any noise or change when the contol is moved. Thanks for the help

 

Sounds like the fan switch. Check the appropriate fuse first. If that's not it, it might be something as easy as the connector under the left side of the center console being loose. Pull the tunnel pad on the left side off and it will be right there in the front attached to the fan switch. Try your connection and see if that creates some air movement. If not take a 12 volt test light and see if you are getting power to the switch with the ignition on. I just happen to have the electrical manual here and see that the brown wire coming into the switch is the hot wire. After that it is different depending on whether or not you have a/c. I have scans of the complete system that I am going to post for someone else tonight and will get them posted here as well.

Bob

 

Hi again Bob
I checked for power at the control switch and there was none. The fuse looks ok but when I get a chance I will replace it anyway. I found the core bypassed so I hooked it up again. The car seems warmer but I will need to get the blower working to know for sure. I had read before about putting a jumper on the fan but I wasn't sure which lead to use so a print would be great.
Thanks again

 

Hi Jerry
I filled the reservoir and pumped the brakes but the light stayed on. Is the light tied in with the park brake. The left rear cable is siezed. If there is a connection do you know where it is located.
Thanks

 

Posted here at the bottom.
http://www.corvetteactioncenter.com/...threadid=18589


[Modified by Bobchad, 9:48 PM 11/18/2002]

 

The brake light is activated by pulling on the parking brake lever, but heck if I know where the switch is. I looked in my Haynes manual and my AIM but I couldn't find it. Maybe my eyes are too blurry at this point. Hopefully, someone else knows. I had my parking brake handle off to replace the front cable, but I can't remember a switch. I wouldn't think that a sticky rear cable would cause the ligth to come on. You may be able to get it un-stuck by taking it off and hitting it with some WD-40 and tugging on it. The cables aren't too expensive, but a parking brake job can be a bit of a pain. At this point though, I kind of doubt that's your problem.

 

There are two lights in the brake light window, one is controlled by the parking brake lever, the switch is inside the console attached to the parking brake handle.
There is another switch that is activated by a pressure differential between the front and back brakes. It is usually a sign that you need to look at the brakes. C-3s are notorious for getting air into the brake lines. This normally comes from the rear brakes. The rear rotors have a tendency to have run-out problems, as the rotors turn they cause the brake pads to rock minutely as the wheel turns. This rocking can suck air through the seals on the brake pistons and into the calipers and braking system.
There are several makers that sell brake pistons that have o-ring type seals that prevent this "pumping" of air into the brakes.
Turning the rotors is usually ineffective in preventing the pumping, since many times the wobble is coming from the whole hub and rotor assembly. There are ways of correcting this, one way is to have the whole rear assembly rebuilt and the whole assembly set for correct rotor run-out.
The other way is easier and cheaper, it envolves cleaning the surface of the hub to bare metal (get the rust off) then clean the inside of the rotor (get the rust off) so that when the two parts are mated together they are flat together. Then the tricky part, with the rotor back on the hub, bolt it down with the lug bolts and torque them evenly. Then get a dial indicator and check your run-out. Mark the high points of the rotor with a Sharpie or pencil with the amount of run-out you see at that point. Then unbolt the rotor and take it off. Then get some shim material and shim opposite of the high spots on your rotor. Place the shim material around the bolts on the hub, the shim material should be half the thickness of your high point run-out. I used some very thin pieces of stainless steel shim stock that I got at a pump alignment shop. Any metal of appropriate thickness will work. One of the guys used pieces of a beer can. :D
The lower the difference in run-out the less likely you'll have air in the brakes. Anyway, get zero tolerance o-ring type pistons for your brakes, they'll help more than anything else.