no heat in my 72 dart...AC car

[jhaas63]

I can't get any heat in my 72 dart. It originally had air conditioning. I bought a heater core....thinking it was plugged. I started to swap it out and it looks like the "box" that has the heater core in it probably needs to come out. Is that right?

The dart blows air, it just isn't hot. Is there any issue here since it used to be an AC car?

 

['74 Sport]

Yep, the heater core is located inside the A/C-heater "box" that you suspected comes out. Having the A/C disconnected or completely removed has nothing to do with the heater working properly - totally separate systems.

You'll find two heater hoses connected to the core's copper tubes which penetrate the firewall. One of them has the water control valve mounted inline. I'm not sure on your '72 if the valve is cable or vacuum operated. Regardless, if the valve isn't operating correctly, it won't allow the heated water to circulate through the heater core. Take a look here and you'll see what I'm talking about: WATER CONTROL VALVE

You need to locate the valve and determine if it opens/closes properly. Do you know if the heater controls work in the dash? You said the fan blows, but does moving the temperature lever cause the blending door inside the "box" to move? Basically, the lever operates a cable attached to a door that pivots to direct hot air to blend with cold air to adjust the temperature.

Moving the control switch to "HEAT" should open the water valve and hot water flows through the heater core. If the heater control switch in your dash is vacuum operated, it's possible that one or more of the vacuum lines are disconnected or leaking. The old switches are also very prone to having their small plastic nipples broken off where the vacuum lines attach.

Do a quick check on these items and let us know what you find.

 

[72bluNblu]

Has the heat in the car EVER worked?

If not, check the heater hoses. I've seen more than one car that's had the heater core bypassed by hooking the heater hose output on the water pump directly back into the input. This is usually done because either the heater core or water control valve leaks. If the heater hoses are hooked up correctly, then check the water control valve like '74 Sport mentioned.

I would bet on one of these two things. If the heater core is so plugged that NO water circulates (and if any did you'd get warm air), then the lack of heat will be the least of your worries.

 

[buffoni88]

Would using the leak stop copper stuff cause the core to clog up? Mine USED to work, it used to get very hot actually. Now that I've got my engine all put back together, the heat stopped working!

 

[Sedanman]

Does your car have an a/c heater box? I had this same problem & just noticed that the trap door to the heater core was closed & not allowing air to go into it. The vaccume pulls the door shut. I opened the PS lower dash vent to notice it & there is another trap door with a vaccume pod underneith on the front as well & if you push or pull it open you will see the 1 in the vent open & close. This may help