Car Heater Question

jtdoyle1

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Apr 11, 2006
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Ankeny, IA
I was driving my '99 Plymouth Voyager to work today and when I was just about there (car had been running 45 minutes) I noticed that the heater wasn't blowing hot air. It wasn't cold air, but it just wasn't as hot as usual. Then I noticed that the temperature gauge hadn't moved off "C"

Any ideas?
 

johnstoncy

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Oct 18, 2006
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www.rtsports.com
I was driving my '99 Plymouth Voyager to work today and when I was just about there (car had been running 45 minutes) I noticed that the heater wasn't blowing hot air. It wasn't cold air, but it just wasn't as hot as usual. Then I noticed that the temperature gauge hadn't moved off "C"

Any ideas?

Stuck thermostat?
 

UNIGuy4Cy

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The thermostat is stuck or the antifreeze froze as it had too much water in it.
 

jtdoyle1

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Apr 11, 2006
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Any quick fixes for either of those.

If antifreeze should make a mixture of Antifreeze and warm water to unfreeze it or just take it in?
 

CO4Cy

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Nov 19, 2008
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Any quick fixes for either of those.

If antifreeze should make a mixture of Antifreeze and warm water to unfreeze it or just take it in?

Start by replacing the T-stat. The concentration of antifreeze should not make a difference in the coolant getting hot only the freezing point.

I had the same issue with my Blazer last year. Drove up to go skiing and the car didn't heat up the whole time. I replaced the t-stat and all was well.
 

UNIGuy4Cy

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I would have someone check it, it would be cheap, thermostats are very sensitive and I don't mess with Chrysler products, to check the antifreeze, there should be an overflow located just off the radiator, open that and see if the antifreeze is frozen, if so you will need to take it to a warm garage to completely thaw with the temp the way it is today and the amount of antifreeze in the vehicle, then add more antifreeze that is not diluted. Check the antifreeze before you have someone look at the thermostat though.
 

Tre4ISU

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It's the thermostat. It is stuck open. Get that replaced and you will be all fixed up.
 

bufante

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Nov 27, 2006
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There are some tubes going into your firewall, that send heat/ac etc. Feel those, if they are hot, then the thermostat might not be the problem.

I had an actuator go out in my dash, causing the hot hair to be blocked from coming in...for you sake I hope it's the thermostat!
 

swiacy

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Apr 9, 2009
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What's the level of antifreeze? If you are low, the t-stat can not operate correctly. Check that first. In an older vehicle like yours your hoses can be seeping around the hose clamps. You could also have a crimped hose that is not allowing the antifreeze to flow through the t-stat correctly. Do not assume that the t-stat is the problem, a lot of times the problem is a simple flow issue and the mechanic just wants to make a qujick buck on a t-stat install job and new t-stat mark up.
 

ISUAlum2002

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Apr 11, 2006
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Sometimes in very cold weather like this, the radiator has so much cold air flowing over it that it keeps the coolant TOO cool. The heater core needs hot coolant to do its job. If its not the thermostat, I'd suggest blocking off some of the front of the radiator.
 

CyCloned

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Oct 18, 2006
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What's the level of antifreeze? If you are low, the t-stat can not operate correctly. Check that first. In an older vehicle like yours your hoses can be seeping around the hose clamps. You could also have a crimped hose that is not allowing the antifreeze to flow through the t-stat correctly. Do not assume that the t-stat is the problem, a lot of times the problem is a simple flow issue and the mechanic just wants to make a qujick buck on a t-stat install job and new t-stat mark up.

This is what I would check first. I have had a couple of cars that the heater would not work right if the antifreeze was a pint low. Of course if it is low than it is probably leaking somewhere.
 

kingcy

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This is what I would check first. I have had a couple of cars that the heater would not work right if the antifreeze was a pint low. Of course if it is low than it is probably leaking somewhere.

A pint low really isnt that much. I wouldnt worry too much about a leak at a pint low. Unless it is a pint low on a regualar basis. Most people over look checking their water level.
 

usedcarguy

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Apr 12, 2008
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If the antifreeze was frozen, the engine would overheat as the ice would restrict flow. Since the gauge hasn't moved off of Cold, then a stuck open thermostat is the likely culprit, although being low on coolant could also cause that condition.