Cold air coming in on passenger side floorboard

[90C1500]

When it's cold out, cold air blows in on passenger floorboard on my 1990.
Any suggestions on what it could be and how to fix it?

 

[Horns]

Gaskets around the heater core lines?

 

[great white]

Gotta get under there and feel for where it's coming from first. Otherwise, we're shooting in the dark...

 

[90C1500]

I will have to get someone to drive while I check. It seems to blow more the faster you go.

I can remember it doing this for at least 15 years or more. When my grandfather had the truck before it was given to me.

 

[great white]

I will have to get someone to drive while I check. It seems to blow more the faster you go.

I can remember it doing this for at least 15 years or more. When my grandfather had the truck before it was given to me.

Ah, that's useful info.

Couldn't tell if it was when the fan was blowing or not.

If it's speed related, I would suggest you look up inside your recirc opening. It's on the passenger side under the dash. There is a door that selecting inside or outside air.

The motors are prone to failure.

If it has failed at an intermediate position (ie: door is halfway opened/closed) you could get outside air blowing in from the base of the cowl. You can also select your recirc switch on and off and see if the door moves.

If it doesn't, your motor is dead.

Just so we cover all the bases, make sure your selector is not in one of the defroster positions or the recirc door is defaulted to outside air and will not move.

 

[90C1500]

It seems to be in any position but I will check. I am almost positive it's outside air coming in because the cold comes in even when the heat it on.
I don't notice it very much because I'm driving and have the heat blowing fine in my side. It's just when I have a passenger that I think about it because they say something about it.

 

[90C1500]

I also have the push button style controls.

 

[great white]

Ah, must be the "90" part of your screen name.

It's been a while since I messed with one, but I think the 88-94 had a "fresh air flow" scheme that always lets a little ambient into the cab...

 

[90C1500]

Should it be letting so much in that passengers complain about the cold air coming in?

 

[great white]

Should it be letting so much in that passengers complain about the cold air coming in?

Well, my wife is a tiny slip of a thing and wraps up in a blanket in the summer and she never complained about my 89 blowing cold on her...