A/C blower motor only works on high

[ryoung415]

Hello,

New SB owner. It's an '87 lwb with a 350 and factory air. When I got the truck the fan didn't work at all. I have replaced the fan on the firewall and replaced the speed selector switch in the dash as well as the resistor in the box next to the fan under the hood. Now the fan only works on high regardless of whether I have it on A/C, vent, or heat. Before I order a relay, is there anything else I need to check? Or will a relay even help?

Thanks!

 

[chengny]

Fan relay is all that is left to replace:

 

[ryoung415]

Thanks for confirming it. I didn't want to throw more parts at it if it is a wiring issue.

 

[chengny]

First, before buying a new relay, check that the relay coil has a good ground connection. Check the black wire for continuity - also that the ring terminal is clean and tight to the firewall:

 

[Hoodbj]

I agree with chengny, has the exact same problem on my 87, replaced relay for about $15 and now works great.