A/C Fan speed issue on 1970 C10

[BBoatner]

Hi Everyone,

I'm new to this forum and hope someone can help me.

At my wits end trying solve the problem with the "blower" on my 1970 C10 with factory A/C. The problem is that when I put the fan speed switch in the first position nothing happens. The fan barely comes on with the switch in the next to last position, and the speed increases only slightly with the switch in the last (high) position.

I have replaced the fan switch, fan relay and "resistor" in the air box. I also replaced the fan motor (not realizing I had to pull the hood spring to do this until after much sweating and cursing--bummer!). All connections appear tight and the fan motor appears to be properly grounded.

I cannot think of any other parts to replace and do not know what to try next.

Help!

 

[jef5150]

1 common thing is a bad ground on the relay itself.Check that, maybe run a "temporary" extra ground wire to the body.Heres a wiring diagram maybe it will help ya out a little.


jeff

 

[BBoatner]

hmm...looks like a former owner attempted to "temporarily" ground the relay because it is just hanging from a black wire. I really cannot tell where the relay is supposed to be attached to. Maybe it's not really grounded and that is the problem!

 

[Soba_03]

Fan speed

Bboatner,

I did this on mine last weekend. on your fan control lever there is a small bushing on the switch arm that may or may not be there. if it's not there then you may not make the full trave with the switch, in which case you may only seem to have 2 speeds as opposed to three. Also I've found out that the connection on the reistor and the switch at the control lever after years don't make a solid connection. clean the prongs on both the reistor and the switch with a little sand paper and make them shiny, add a little bit of dielectric grease and your problem should be solved. Also if your heater box cables are tight and applying pressure back on your lever it could cause your fan switch to be pushed back once you slide it over. In this case a little adjustment of the cable or repositioning of your heater cable may help resolve your problem. I'm almost certain that the problem that your having is connector related. With that said make sure that your switch is free moving. Should not take a great deal of force to switch it into all three fan positions.

I hope this helps... so for it being so long.....