[MARINA 66]

The high Blower Switch on my a/c in both my '78 and my '79 T/A's is not working. Otherwise the a/c works perfectly in both cars. When the blower switch in in high, one car's blower runs on low, and the other car's blower shuts off completely. Blower swithces work fine in low through medium. Based on the manual, I figured it was the high blower relay, so I changed them out in both cars. No change to the problem, however. Since I can't figure out what the manual is suggesting now, I don't know where to look without taking the dash out and start fooling with the switch. There has to be a better way. Help ??

THANKS, JAY B

[MARINA 66]

I read some older threads, and aparently this is a common problem. I looked for a fuse at the alternator on my '79, since that car is totally stock. I see a connector on the red wire, but no fuse. The connector half way back on the passenger side of the engine looks "iffy" inside, as well. I guess I'll start looking for power on either side of the connectors and see how I do. My '78 has no red wire going to the connector at the back of the alternator, so I will surely start at the relay and build the circuit back to the alternator, before I can go further. I love inheriting someone else's science project.

[chiphead]

Do those cars have "blower motor resistors"? Typically cars from that era with multiple blower speeds have a multi-tap resistor.

The dash switch changes between the different resistor taps, which changes the speed of the fan. When the resistor dies, you only get high speed, or nothing, or a weirdo speed as the resistor shorts out. The blower motor resistor is usually located on the engine compartment side of the AC/Heat housing. It is usually held in with two screws in an obvious place. It will have a 3 to 7 wire connector attached to it, and will look like several electrical heating coils. Those are the resistors for slowing the fan motor to the different speeds. They are cheap and a common failure point.

[Squidward]

The hi speed switch on the ac control gives 12v to actuate a relay on the outboard side of your evap box. When this happens, power goes directly from + alternator post, thru fuse, thru relay contacts, and then to blower + lead. It's almost always bad/missing fuse, or a bad relay. All other fan speeds work because the normally closed blower relay contacts supply power to the fan when the relay is off.

Let me know if you need more. I have a 77 schematic, and it should be almost the same.

[MARINA 66]

Thanks so much for the responses. When I left yesterday I was fit to be tied. Looked at both cars this morning, with my multimeter, and suddenly everything became clear. The plug half way back on the passenger side of the engine was corroded on my '79. Brushed, cleaned, plugged back in - fixed !! On my '78, some scientist had cut the red wire from the alternator to the relay. Replaced, cleaned up the harness - fixed !!

Jay B