Weird left turn signal and heater air flow issues

[68Bowtie4x4]

My 72 Chevy 4x4 will erratically flash the left turn signal dash light while I'm driving down the road. When I click the left turn signal it works normally, as well as, the right turn signal works normally too.

My pickup has the non-AC heater system, has brand new levers, cables, and heater fan switch installed. I have low and high speeds for my heater fan, defrost blows when I select defrost, and floor heat works when I select it. But it seems as I don't have very hard air flow through either defrost or floor heat.

Could it be the rheostat for the heater fan? Is there an illustrated heater check procedure to determine where the issue resides?

Thanks.

[PanelDeland]

Turn signal almost acts like mine did when the switch in the column was bad. Someone will chime in with a way to troubleshoot.
The heater is most likely the squirrel cage fan being clogged, a lot have a mice nest in them or just debris. You have to pull the fan to look in it and see. the heater core may have stuff in the fins also. A shop vac will come in handy if that's what's slowing it down. If you have the speeds it's not the resistor, but it's under the dash on the passenger side if you want to check it.

[BruthaMan]

Turn signal issues is the switch, which looks like:

http://www.ebay.com/itm/1967-1968-19...926d11&vxp=mtr

I have the same problem in mine. The left signal will arbitrarily flash when I hit small bumps in the road. It will also not cancel automatically after a turn.

I have a replacement for it, just haven't done it yet.

Heater air flow. Typically in these old trucks, leaves and debris get into AC or heater box, under the hood and down along the fender edge to the fresh air vents. On a lazy Saturday, from under the hood, remove the heater box from under the hood and you will probably find all sorts of leaves and years of debris. A shop vac will clean it up good. In the cab, hold open the fresh air vents above the kick panel area, and you can probably reach in and feel leaves and other debris. Shop vac it out. That should give you more airflow.

Don't expect air flow like the new GM trucks or cars. Mine is clean enough to eat off of, but compared to newer vehicles, high seems like low to medium.

[68Bowtie4x4]

The turn signal light flickering was the front left marker light filament was broken and hitting the turn signal filament causing the left turn signal light to flicker on.

The heater box had 42 yrs of leaves and debris sucked up against the heater core, so I cleaned the heater box and installed a brand new heater core since I had it a part. Has good air flow and heat now.