AC fan problem

Thanks Gene, I'm not as tall as you but, my eating habits make it hard to reach certain places.

Some of our cars have a hot lead directly from a fusiable link to the high position on the blower relay.  Some are fused or use a circit breaker.  If you have a high speed blower relay, the relay uses the switch to control the lower speeds through the resistor block, and uses a separate power supply to the relay to supply direct power through the relay to the blower motor for high speed.   In this case the high speed switch on the dash supplies power to trigger the relay when you select high blower.kstyer38920.8302430556

[QUOTE=annicorvette]Do you have a rear defrost ? if you do check this--in my 78 the fan is wired so the high speed fan is disabled if the rear defrost is on. Don't ask why i just know it is.[/QUOTE]

Is it possible they use the same circuit and if both are on high the AMP draw would be too high?

More than likely.

It should be noted tho, that on the '74(and earlier cars, up to '77), the rear defrogger was simply an extra blower fan that blew on the rear winder. The later cars('78-82) wid da large rear winder had imbedded defrogger circuits in the glass.
The 'lectric defroggers take quite a bit-o-'lectristity, which is why they are almost always on a timer. Adams' Apple38951.7151273148

I have just the reverse problem.  The high speed works but the lower setting do nothing.  Any suggestions?

That could be the blower switch, or the resistor bad. It could also simply be a fuse.
On most cars, the high speed blower is on a completely different circuit. This is why most of the time, it is the high speed that doesn't work, but the low speeds do. But, the other way happens also. I would start by checking fuses, and then the switch.

It works !

Now...you know the first time you need that high speed blower with the A/C on, it ain't gonna work!!

Sounds like you may just have a bad connection somewhere, or one of the micro-switches in the control unit(thumbwheels). Hey, as long as it works, eh?

I have no idea how it got fixed.