Blend door - no heat

97 caravan,

Need to know if blend door is cable or vacuum operated.

Ok, Blend door wasn't the problem,

Van has some heat when idling but cools off as I drive it.

Thermostat ??

Opinions please

Check coolant level first. Then go for thermostat.
MT-2500

Sounds good to me

New thermostat in, had a little bit of heat for a day, now nothing.

I am thinking restricted heater core and want to flush it,

Problem is location of hoses, Crawled under car and there is one hose connected at the back of Water Pump, another into a T-shaped flange on opposite side of engine. Short hoses changing into piping running behind engine to firewall, not sure if these are to heater. Can anyone confirm if this is accurate.

Thanks

97 caravan, 3.3 V-6

Just amazed how useful posting on this site has been !! :rolleyes:


Ok, I have flushed heater core, minimal heat output now.

Anyone have experience with blocked airflow ?

Seems that when I switch blend door from hot to cold, airflow through vents dramatically increases.

Wondering is core is hot but low airflow causing lack of heat.

Check hoses inlet and outlet going to and from heater core. They should be hot to the touch.
Also run the self diagnostic on your air and heater controls.
Any yellow lights blink on them?
MT

Hoses are hot and I'm getting some heat, but very little.

Checked computer and got no codes, just a 55

Or is there a different test to check the AC/Heating system?

Sure is.
Try this.
MT
Let us know how it goes and post codes you get.
http://members.troublecodes.net/crunch/97car.pdf

I had previously tried a test holding compressor and rear windsheild buttons down. That left me with recirc. and compressor buttons flashing together when I start van. Stops after 10-15 minutes

When they stopped flashing, I tried the other sequence as described on Link you suggested. Van passed that test.

But still have other buttons flashing on start.

Any idea how to make them stop ??

Print out the test and go threw them step by step.
To enter calberation you press rear wash and rearwiper buttoms for 5 seconds untill leds start flashing and the let it go threw the calberation.
MT

Did some additional research.

Apparently Van is passing the calibration test but failing the cooldown test.

Info I find is a Catch-22 ,
If both lights flashing, need to run cooldown test, which then ends with lights flashing.

Can't find any info for getting codes.

Sorry MT, I don't want to appear dense, but Test instructions are a little confusing.

I should run calibration test and when done, I do not exit it, but begin button sequences as described in test procedure ?

If the rear wiper and inter wiper are flashing alternen there is a level one code.
If they are flashing together rerun calberation test.
Yes the test is confusing.
Just copy it off and go threw it step by step,
MT

Ran test several times

Level one - no codes

Level two - Flashing decreased when when selector moved to defrost and increased when back to panel.

Level three - Flashing slightly faster on hot than on cold

Level four - different flashes over different tests 7+5 / 6+6 / 6+4, I believe this is Temperature so that would be normal.

Still have recirc and a/c buttons flashing together meaning van failing cooldown test.

Suggestions Please !!

You may have to get the dealer to check it.
Good Luck
MT

You may have to get the dealer to check it.
Good Luck
MT
If Vac operated doors check for vac leaks also check for leaves or debri in heater core or ducts dont know if this will help but is first thing I look at in older cars

Pulled cover tocheck for blockage in fan, all clear, recirc door is sluggish but does reach both open and close positions

I can see A/C core from small rubber access hatch that temp probe wire goes through. Used compressed air to clean core, got some small debris out of vents.

The real problem I have is not knowing what is between the A/C core and the heater Core. I am assuming that is the Blend door location, which may be the casue of my problem. I can't confirm that it is reaching it's stops. I noticed the A/C wasn't working real well this Summer, felt cool but not cold. Now heat is warm but not hot. Seems to indicate I am getting mixed air.

Any idea where I might find a diagram of the Heat-AC system?

And now the cooldown test failure has the lights flashing fot 15 minutes every time I start the van.

Technology is good ? LOL

Think I have finally found problem,

I have constant outside air entering heating/AC system. This mixes hot air with AC in summer and cold air with heat in winter.

I finally figured this out by taping up the Air intake vents on the hood in front of the windsheild, I then got heat instead of cold air when Van was being driven with controls in heat mode. What little heated air that has been coming out, had been turning cold as soon as vehicle was in motion

Question is what controls air flow entry into the system, A door of some kind I am assuming, but where is it and what controls it.

There is a recirculation door in the passenger foot area, but this opens and closes by its control button yet doesn't seem to affect the intake of outside air.

Anyone familiar with the vehicle AC/Heat system?

Here is a link to the best info besides a factory service manual.

http://www.alldata.com/products/diy/index.html

MT

Replace heater core

If it were bad, that might be a good idea.

Did you read the previous posts ??