ne heat!!

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74valiant

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i just recently installed a new 318 in my car. i pulled the ac, and all the smog junk. i just noticed that my car doesnt have any heat now. the fan will turn on, but it blows cold air.

what could this be?? anything to get me started would be awesome!!



thanks jason
 
The only thing I can think of is this. There are a bunch of doors in the heater box that swing open and closed to let in heat,or ac air, or out side air. Mabby one of the doors is stuck or in the wroung position?

Sorry but that is all I can think of.
Good luck.
 
You may have a vacuum operated hot water valve under the hood too. All that stuff needs vacuum to operate but if that valve is stuck closed , no heat. Feel the hoses after engine warms.
 
I agre with redfish,vacuum.After tearing out the A/C, there would have been atleast 1 line going to the hoses.Samething happened on an older Chebby when i tore the A/c off.
 
My guess is when you removed the AC and emissions junk, you accidentally disabled something on the heater box. Probably like someone said, a vacuum line. The AC heater boxes use vacuum to move the doors sometimes. Another possibility is that a door is simply stuck preventing the air form passing through the heater core. The core itself could also be plugged up.
 
whats the round black plastic thing thats on the pass. fender by the firewall?
 
I believe thats a vacuum resevoir. There will be a vac line that goes from the carb to the vac resevoir. There will be another line that goes from the vac resevoir to the control in the dash. There will be vac line that goes from the water valve to the control in the dash as well.
 
The vacuum resivoir compenstaes for a brief drop in manifold vacuum when the throttle is opened suddenly. The lack of a resivoir wont stop things from working. What happens is this... You're idleing at a red light and everythings lovely. Light goes green and as you accelerate away the air flow switches briefly from heat vents to defrost vents. A reserve supply of vacuum prevents that.
 
i found the problem. my vacuum valve in the engine bay must have a torn plunger. i moved the valve manually to the open position, and it works. it was way to easy to fix to have waited this long to do. oh well, could have been worse. where is a good place to get these? would a used one work off a newer car??
 
New ones are available. Made of plastic, they don't look original, but work fine. NAPA has them. Probably other places as well.
 
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