little heat from heater/defog

[bradbig]

Hey gang! Out for the first decent drive with my wife last night in my 73. Success! It went very well, but I have learned that my heater core doesn't put out much heat. On the way home, the outside air temp. dropped, so I turned the interior heater fan on, moved the air temp. lever forward, and the air direction lever to "heat", but we only got a little bit of warm air.

I had previously inspected the system and installed a new hi/low blower motor switch. Everything works correctly. The fan blows nice and strong, the recirc-fresh lever works correctly, and the lever that controls the cable that activates the heater valve works correctly. I don't see any signs of leakage at the valve itself. So, everything appears to function correctly, but there's not much heat, and yes, the engine does reach operating temp. to the point of turning the radiator fan on, within 5 mins. or so, at idle speed. The only thing I can think of is a plugged/partially plugged heater core. Any other possibilities?

[azruss]

the air lever, closest to the driver controls the air through the heater. If you have it forward, you have the air shut off and no heat. That lever should be back and the heat lever (the middle one) should be forward. The triangle marking tells the story. move in direction of the point, then that system is shut off. move to the fat end of the triangle, it is full on.

[bradbig]

I thought the lever closest to the driver controlled the air source - recirculated or fresh, and the middle lever opened the heater valve to allow hot fluid in, and the lever closest to the passenger controlled the direction of the air, either to the floor or to windshield. I printed off the few graphics posted on fs.com that indicate what I've described. Am I wrong? So you're saying that the lever closest to the driver completely shuts off the flow of air, if it's pushed all the way forward, towards the dashboard?

[vandor]

It does control the air source, but your choices are:
1. Outside air
2. No air

[azruss]

There is a flap underneath the windshield cowl. When it is open, it lets air in from the grill in the cowl. this flap is controlled by the air lever closest to the driver. With the exception of the early cars with the separate fresh air ducts under the dash, this is the only source of air. All the air from the flap goes through the heater core. The middle lever opens the heater core valve allowing coolant from the motor to circulate through the heater core for heat. The PS lever opens a flap on the bottom of the heater box. when it is open, the air through the heater core dumps out at the 2 openings on each side of lower console just below the upper console. When that door is closed, it forces the air back up behind the heater core to the defrost vents in the dash. As Csaba said, there is no recirculation system on these cars.

[bradbig]

Thanks very much for the input. I did take the section off between the hood and the windshield. That whole area underneath had everything from dead bees to pine needles, and a lot of dust and accumulated dirt, to the point that the water drains that let water drain out down the firewall, were partially plugged. The rectangular opening with the flap to allow fresh air in also had a lot of crud in it, so I vacuumed it all out, did some scraping and lubricating, and now it's nice and clean.

I do have the two round openings with flaps (these appear to be a simple fresh air vent for comfort?), and these also needed cleaning, lubricating and a bit of repair (the cotter pin that keeps the flap in position so it can be opened or closed was missing) on one. I missed seeing the little levers under the dash for controlling these.

So the various little graphics that can be printed and affixed to the centre console tunnel are partially incorrect. There is no "recirc", just on or off.

I still have more checking to do, clearly. Thanks for the help, thus far.

[Redline]

The left lever controls the amount of oil fumes that enter the car.

[azruss]

As a side note, auto makers have been puting vents at the bottom of the windshield for decades. This is a high pressure area in wind flow across the car so a very logical place to draw air.

[paintdudeluke]

back to the original question; you asked about any other reason for poor heat. A crapped up valve between the hose and the core up under the dash above the pass left foot. Way up in there. Mine was clogged, I yanked it and put a new valve under the hood. It stays off all summer and on all winter.