Ken Styer and FLA Vette -

Thanks for your help. I finally got a chance to check out my fan relay and it is good. Now what...

I still don't have a medium or high speed and I am not sure I have a low - anyway I can't hear it. Air does come through the vents at speed - 50+mph. and I can heat it or AC it somewhat. The control unit makes a hissing noise when I turn the engine off and I sometimes think I hear the fan "rattle" at the same time but both noises are very brief. I replaced the a/c-heater control switch - just the little vacuum part - a year ago because it hissed all of the time so I doubt that is the problem.

Any suggestions? I have no clue where the fan is even located let alone how to test or remove it. I have both a shop manual and an assembly manual but they are not a lot of help. Could one of the vacuum door opener/closers be hung up thus the noise and no fan? I have to believe only one thing is causing both problems but what is it?

This is a great forum and I hope I can help others some day - I just have to learn more.

Thanks.

Herb Harlton

'80 Coupe - Black and not so cool in this summer heat

Look in your manual and locate the blower resistors. They supply all the power to the three lower speeds, and to the one side of the blower relay. If the resistor break or burn, they can lose any or all of the three lower speeds.

With a good relay, and likely a good switch, and the power to turn on the relay is there so the fuse is okay, the resistors is highly suspect. They sometimes look good, but have poor contact. So check them with a test light or meter.

It will have four wire connectors, and two screws that hold it into the duct work. You won't see the actual reisistors until you remove the screws and pull it out. The resistors are in the duct work to keep air running over them to help keep them cool.

|UPDATED|8/22/2004 7:28:13 PM (AZT)|/UPDATED|

Ken -

I was poking around near the relay the other day and found these resistors but had no clue what they were. I will check them out. Any thoughts about why the vacuum hissing and maybe fan rattle when I shut off the ignition?

Where is the fan anyway? My best guess is that it is by the passenger's feet. That was where I heard the shut off rattle from. Is it accessable from there if I need to get at it?

A previous ownner stuck a yucky deodorant cake somwhere in the vent/ac system and I can't find it. The car smells like a toilet bowl deodorant every once in a while - not good for a Corvette.

Thanks for your help.

Herb

HerbH said: Any thoughts about why the vacuum hissing and maybe fan rattle when I shut off the ignition? Where is the fan anyway? My best guess is that it is by the passenger's feet. That was where I heard the shut off rattle from. Is it accessable from there if I need to get at it?

fan is behind map pocket on passenger side.

where is the vaccum leak coming from ?

You should be able to access the fan from under the hood, but it's not easy to reach. Just as Ben said, it's in front of the map pocket area. The rattle could be a loose fan cage, rattling as it stops, or there could be some debris in the fan cage area. Dry leaves love to make this noise.

The vacuum leak will need to be tracked down by listening to the hiss. It could be in the switch in the console, or anywhere there is a vacuum circuit.

Grab a piece of vacuum hose about 2 to 3 foot long. Stick one open end in your ear. Use the other end to trace along the console and dash to listen to the sound. When you get to the leak you will hear it very clearly in the end of the hose. You need to get right next to the leak. Several inches away won't help. But if you trace all the vacuum areas, it will show up.

I bet it's the first time somone told you to stick it in your ear and was trying to be helpfull.

Ken and Ben -

Thanks for the help. I finally got a chance to work on my car over the weekend. The problem was the resistor contacts. I cleaned them and - WOW - the fan worked. Other than my time it was a cheap fix too. The cost of a piece of sandpaper!

Great thing - this C3 Forum

Herb Harlton

Glad to hear it Herb. Your welcome.