hvac FAN CONTROL

I just bought a '70 and have learned that the heater/AC fan does not work on the high setting. It works on the other settings. Is the problem likely to be the switch or the fan? Is there a relay of some kind that I should look at?
Thanks
Mickey

The car does have a high speed blower relay. All blower speeds go through the relay. All lower speed go through a resistor block and selected by the blower switch. They go to the blower relay, and to the blower. When High is selected the switch turns on the relay which disconnects the low speeds and applies battery power to the blower motor. If the high side contacts in the relay burn out, you will lose high speed. You may also have the battery power to the relay gone.

There are a total of five wires on the relay. One goes to the blower motor. One from battery power, always hot even with the key off. One from the low speed blower control, always power with key on, but varying amperages. One from the high speed position on the blower switch to turn on the relay coil, on hot key on, high speed position. One to ground the relay coil, always grounded.

Hope this helps

Ken Styer

|UPDATED|4/5/2004 7:02:45 AM (AZT)|/UPDATED|

Thanks for your reply. It helps a lot.