I took my 1996 Aerostar to get a coolant leak fixed. It had leaked down 4 litres+. I noticed the gauge was in the red. ( thank goodness, I saw it ) When I got my vehicle back from the shop the rear heater worked but the front heater didn't. I took it back and they flushed it out to get any air bubbles and now the front heater works and the rear heater doesn't work. Could it be the controls that are faulty. If so, is that very expensive. I'd rather have front heat then rear heat for defrost etc.
Or could it be something else? It's odd that I get one or the other but not both.


Thanks, I'd appreciate any advice.

 

First, I'd make absolutely sure that there is no air in the rear system. Ask them to put a vacuum on the cooling system to purge out all air bubbles. If that doesn't fix it, time to start looking for other problems. Seems like the shop caused this problem, they should have fixed it.
The shop should be able to feel the hoses if they are circulating coolant. Any hose that is cold has no warm coolant going through it.

 

If the shop can't bleed the cooling system properly, you might do it yourself. Properly bleeding out the cooling system requires raising the front of the van, like on a steep driveway, hill, or on jack stands. While the engine is cold, remove the radiator cap, then run the engine with both heaters on full. Let the coolant circulate for a few minutes after the engine warms up. Then top off the coolant if necessary, and close the cap.

Also, check to make sure you don't have a leak in the vacuum lines that control the heaters. This was discussed recently here:

https://www.ford-trucks.com/forums/1...-aerostar.html

and here:

https://www.ford-trucks.com/forums/1...wy-speeds.html

There is a long vacuum line that goes to the rear heater to control the air blend door.

 

Wow xlt4wd90, could it be that easy? I will try that, thanks.


Thanks Kruse for replying.

 

It may be that easy if your cooling system doesn't have weird build ups inside that keep air bubbles from percolating to the top. Otherwise, yes, that's the way you would do it for most cars, since air rises above the coolant.

I hope that's your problem though. It could be the controls at fault, and that is usually in the vacuum lines.

 

Does this problem only happen when there is a rear heater? Over the years I've changed hoses, water pumps, radiators, thermostats and all I've ever done is fill it up with 50/50 mix, run it until the thermostat opens, top it off, then check it after a few miles. I've never had any problem with air in the cooling system on either of mine.

 

in my experience it mostly happens with the 4.0 liter

 

There's plenty of air blasting out of the rear heater, but it's cold air. The first time I got it back from the shop I had rear heat and no front heat. When I took it back and they re-flushed the line , I got front heat and no rear heat, just cold air. I can live without rear heat, but it would be nice if everything worked properly. "Big Red" is 20 years old next month and I don't want to spend any more "serious money" than I have to. Thanks everyone.

 

look under the van on the driver's side, between the gas tank filler and the front door;

the Rear Heater Valve and coolant hoses are located exactly under the rear Heater/A/C unit.

look for a thin black vacuum tube which should be connected to the Heater Valve's vacuum port.

before you connect or disconnect anything, look for signs of someone having worked there.

Note that to get Heated Air from the Rear/Auxiliary unit, the Heat position must be selected at the dash switch, and the TEMP **** must be in the red area.