no heat

[baby shark]

'83 sat idle for a couple months. After i got her going again, i noticed heat wasn't working except thru side vents. I topped off resevoir with anti freeze but still no heat. Blower motor works but blasts cold air!!!

[Danglerb]

Could be bad diaphragms in some of the vacuum actuators. Roger at ************ has replacements for some, others the actuator must be replaced. Check for a vacuum leak, how I have no clue.

[stepson]

Originally Posted by Danglerb

Could be bad diaphragms in some of the vacuum actuators. Roger at ************ has replacements for some, others the actuator must be replaced. Check for a vacuum leak, how I have no clue.

To check for a vacuum leak:
First find the blue check valve that comes from the brake booster. Verify that it works correctly(ie. one way only)
Next, from that check valve, there will be some sort of arrangement of 3 way/5 way/7 way splitters. Find the vacuum line that goes straight through the firewall. Try to pull a vacuum on that line. Chances are, you won't be able to and it will leak which verifies that you have a vacuum leak in you HVAC system. That vacuum line goes straight to a vacuum manifold which is located in the bowels of the console inside the car.
To find out which actuator is leaking, remove the driver's side console panel which will give you visual access under the radio and on top of the engine tunnel. You should see the side of the vacuum manifold there. You can check each actuator without removing the manifold, but the color-coded vacuum lines would each have to be cut one by one, tested, and then spliced back using a vacuum coupler. Doing it this way will allow you to test easily as necessary in the future, but then again, you would be cutting your vaccum lines.
The vacuum manifold can be removed by removing the 3 screws holding it to it's protective cover. It's not extremely difficult to remove these screws, but after you do it once, you'll know why most people just cut the lines and splice them.

The line from the firewall plugs into the hole in the rubber manifold
This view shows how the manifold is set up and also shows the electromechanical switches that are activated by the AC head unit.

[Fixer]

Probably just the vacuum line to the main vacuum actuated heater valve control below and behind the lower air box piece next to firewall. Can't miss it.

This is the first place to look. Good luck.-Matt

[stepson]

Originally Posted by The Fixer

Probably just the vacuum line to the main vacuum actuated heater valve control below and behind the lower air box piece next to firewall. Can't miss it.

This is the first place to look. Good luck.-Matt

You are probably right.

[Danglerb]

Heater valve with no vacuum is hot isn't it?

[baby shark]

ok..thanks..i'll take out the airbox and check the vacuum line attached to the heater valve..

[dcarter]

Even if there were vacuum problems, shouldn't he get heat to the center vent? The heater control valve defaults to open.

I have a heater issue with my 87 as well but haven't looked at it much yet. I'm thinking if hot water is flowing through the core (should be able to feel the heat in the return line under the plastic cover for the windshield washer motor, near the expansion valve), then maybe the mixing motor under the drivers side dash isn't working right. Topping off the coolant is next though.

[dcarter]

Adding water fixed my heater! I love a simple fix.

[stepson]

That's the best kind of fix there is.