ScottMHoffman

I have removed the dash from by Cutlass with the goal of 3 repairs.

First was to get at the rust just below the windshield under the chrome trim. Plan to just clean rust behind dash and under windshield and por15 the rust. Is this reasonable? Car is a driver and do not want the problem to get worse. Should I remove the windshield to do a better job?

Second, my fan only runs on high. The car came w/ a/c but is has been removed. I read something about this repair before but could not find again. Need to install something, I think a resistor or something. Any ideas?

Third - The air only good to the defrost. Would like to get it to go to your feet. I know parts are missing because a vacuum line does not go into the motor compartment. But I do not know what one needs to be contected to motor vacuum and if I need any other parts. Can anything be wrong with the dash HVAC controller or the problem usually else where? IE no attachment to the vacuum.

Finally any other small repair while I have the dash out?

thanks,

joe_padavano

Depends on how bad the rust is, but if you plan to use any kind of power tools to clean up the rust remove the windshield to avoid damage from grinding dust or (worse) inadvertent glass contact with the grinder.

Do NOT ask me how I know this...

Motor fan speed is controlled with by a selectable resistor network that's bolted into the HVAC box on the firewall. If the resistor isn't present or isn't hooked up, you'll only get high.

The flapper doors that direct the air inside the car are vacuum controlled. With no vacuum the default position is defrost with limited air to the floor. Your first problem is to figure out what got ripped out by the P.O.

ScottMHoffman

On the fan speed, what resistor do I need and where does it go?

joe_padavano

The resistor is bolted into the HVAC box on the firewall. The airflow from the blower motor helps keep the resistor cool.

MDchanic

Don't take this the wrong way, Scott, but from your questions, it looks like your knowledge regarding the A/C unit in your car is minimal at best.

It would be wise for you to read the appropriate chapter in your Chassis Service Manual, which would tell you how the system works, what the parts do, where they are, and what they look like. That information will allow you to figure out what the previous owner removed and what he left.

If you don't have a Chassis Service Manual yet, you can easily pick one up on eBay, or from one of the usual automotive literature dealers.
You can also get a copy for free from WildAboutCars (the '72 manual has a poorly scanned wiring schematic) while you wait for your paper copy.

- Eric

ScottMHoffman

You would be correct. I have 2 manuals at home about the car and I will look to see what I can find. Part of the problem is the car originally came with a/c and it has been removed by the previous owner so I do not know what was removed and what still exist. I added an a/c delete box from American Graffitti so the fan will push air into the car.

MDchanic

The Chassis Service Manual wil show you these things.

Since the fan resistor is mounted to the evaporator box that was replaced by the delete box you installed, that might be part of the reason the lower fan speeds don't work.

- Eric

ScottMHoffman

In the assembly manual I found the diagram for the vacuum hoses control the heater. The diagram has a vacuum hose going to the "water valve" What is a water valve and does it need to be attached and functional for the air controls to work?

MDchanic

The water valve closes the hot water line from the engine to the heater core.

If it's not there. you may have a minor vacuum leak from the hose (white stripe, if I recall), but no significant problem.

- Eric