Weird left turn signal and heater airflow issues

[80 Chevy K20 4x4]

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.

 

[ashman]

I can't offer much more than speculation on the heater issue, but the turn signal light is most likely a bad ground. If you lose ground on any of your turn signal lights it looks like a bad bulb to the circuit so the turn signal indicator light comes on. I had that exact issue for awhile. It comes on erratically because as the truck bounces around the ground connection comes and goes.
The bulbs ground through the light housing. My problem ended up being a corroded screw that held the housing to the bumper. I cleaned the screw with a wire wheel and tightened it back up good and everything has been fine since then.

 

[ekajkrats]

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.

Are your headlights on when this happens?

 

[80 Chevy K20 4x4]

No, it will do it with just the marker lights on. I'll have to check, but I don't think it does it when the lights are off, so it might be a bad ground on the left front or left rear tail light.

 

[ekajkrats]

Yeah, mine does it when the bumper light is coming loose and losing it's ground. I think also I had the issue when a side marker light going out but that was a year or two ago and might have been a steady dash light since it was fully burnt out.
-jacob

 

[diesel4me]

Check the bulbs,sometimes a filament from the brake light or tail light side breaks,and touches the other,that will make a feedback that can light up the dash indicators also...bad grounds are what does it most often--I had a defective flasher do it once too..

 

[RANDAL]

Heater would not blow very hard in my Jimmy, so I read to put in an AC cab blower motor and what a difference. worth the switch, hope it helps. Also it plugs in and bolts up the same as non AC cabs.

 

[80 Chevy K20 4x4]

The turn signal was the front turn signal/marker bulb filament being crossed onto the marker light filament.

The heater box was full of leaves from the last 42 yrs, so I cleaned it all out and installed a brand new heater core while I had it out. It works much better now.