The factory A/C fan on my 78 Blazer will only run at one speed regardless of the switch position. I checked the array of wire resistors placed in the A/C housing and all three of the coils look OK, nothing burned out. Is there a relay that could be the problem?

Thanks,

Al

 

Are you saying that the fan does run in every switch position but it is the same speed? If the resistors were bad, there would be positions the fan would not run at all. You may be looking at a bad switch. It should be easy enough to check out.

 

Hi Jim,

thanks for the reply.

Yes, the fan only runs on the low speed in any of the 4 switch positions. I recall that the switch is a simple slider type I think.

Can you take them apart?

Al

 

I'm not familiar with that particular switch but if you can get it out, you should be able to see what's going on with it. It sounds like the contacts are not sliding. Probably something broken or worn out. The switch is the most likely problem IMO. Good luck and let us know how it goes.

 

Hi there,

I agree with SlimJim this might be an issue with the contacts. It is possible
that it worn out or it repositioned itself. I suggest you remove the slider and try
to use a pencil eraser to remove any dirt. As I understand the more dirt on the contact the weaker it is to function.

 

change the switch........those years had a big problem with the switches getting hot and they just plain did not know how to build a switch back then and the contacts were built out of thin copper....I ran into this problem on my old 78 i used to have the switches are not to expencive and easy to do