Luke-warm heater.

[Royce]

The heater on my 93 Aerostar is not hot, only luke-warm. I have my second new thermostat. The water temp guage on the dash points at "N" on "NORMAL", but the coolant seems hot to the touch. How should I troubleshoot this?

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the Aerostar section. What was the temperature range of the new thermostat? Did you install the thermostat in the correct direction? Is the fluid level correct? Are both heater hoses the same temperature?

 

[Royce]

The original thermostat was 195 as was the new one, both checked ok to application of heat (on a vise). The top heater hose was slightly hotter (very hot) than the bottom heater hose which was also hot. I flushed the enire engine in both directions with 55 gallons of hot water and replaced with new coolant and clean water. I installed the new thermostat in the same direction as the old one, with the heat element on the block side and the dome facing up (toward the upper radiator hose)...hope that was correct. This all seemed to help a little. Thanks for the reply, any more ideas?

 

[BrooklynBay]

Was the hose hotter before the heater control valve? If so, then the valve might be clogged or not open completely.

 

[Royce]

What heater control valve? The hoses go straight from the block/water pump right into the heater core. I called Autozone to see if they have a heater control valve for a 93 Aerostar and they don't list one. I suspected the control valve from the beginning, but there is no such animal on this minivan. Any ideas? I sure appreciate this help!

 

[BrooklynBay]

Disconnect both heater hoses going into the heater core, and connect a garden hose to one of them. Check the other hose to see if water goes through the heater core.

 

[Royce]

Thank you for your reply. As I mentioned in my initial statement, I flushed 55 gallons of water through both hoses and through the heater core. I also backflushed through the block and radiator. The hoses and core are clear of obstructions. I'm curious about the control valve that was mentioned in a previous reply. It makes sense that there might be such a device in the system, but I can't find one. The various parts houses tell me that there is no such valve in this vehicle.

I really appreciate your help on this.

 

[BrooklynBay]

I just checked my 93 with a 4.0L, and it doesn't have a heater control valve. Do you have a 3.0L or a 4.0L engine?

 

[Royce]

Mine is a 3.0.

 

[BrooklynBay]

Did you check the fan clutch? Do you have an infrared heat detector gun to check the temperature of the engine or the hoses?

 

[Royce]

No, not sure how this should be checked. Not an electric motor. What do I look for?

 

[BrooklynBay]

Grab the fan blade with the engine off, and see if it free spins or feels very stiff.

 

[Royce]

Will do as soon as I can...not with vehicle at the moment (at work now)...later tonight. Can you tell me what it should and shouldn't feel like? What if it's tight? What if it's loose? ( We may be getting somewhere here...this could explain why the water temp guage always shows cool...right?)

 

[Royce]

..also I do not have the infrared gun...

 

[BrooklynBay]

It shouldn't be loose to the point where you could spin the blade, and it will keep spinning. Too still isn't good either. You should be able to give it a slight push, and it will turn, but not continue to turn excessively. Do you have a multimeter with a plug in temperature probe attachment?

 

[Turdle]

Is there a
blend door apparatus in the aerostars?

 

[BrooklynBay]

It has a cable driven blend door with nothing electric.

 

[Royce]

Ok, I'll spin the fan and try to determine the resistance. As far as the blend door, where would this be? I have a mutimeter, but no temp probe attachment.

 

[BrooklynBay]

You don't have to open everything up to test it. Turn the cold-heat dial, and listen for the sound of it moving. It should feel a little stiff since it's moving a cable & large flap.

 

[Royce]

The flap is operated by vacuum. I can hear it closing when I place the control knob in the "vent" position.

Also, the fan moves easily with (some) resistance. When the engine is off, it will not free spin, but can easily be turned. Is this O.K?