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post #1 of 3 (permalink) Old 11-27-2008, 08:41 PM Thread Starter
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Heater not hot

On my 1996 Jetta with 2.0L the heater is not working properly. It is blowing cold air. The blower is working properly. The vehicle is not having overheating issues. The hoses leading to and from the heater core are both as hot as the upper radiator hose. When the blower is on and I turn the hot to cold knob I can tell the air gets cooler when I switch from red to blue but the air is not hot or warm for that matter when it should be. The heater core is not leaking inside and the coolant level is always at the appropriate level. I am at a loss on what to do next to troubleshoot this issue.
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post #2 of 3 (permalink) Old 11-27-2008, 09:29 PM
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have you checked the thermostat? because for some odd reason they seem to make a difference....

96 Jetta GLS-Sold (unfortunately)

Now have a 2009 Dodge ram 2500 (but thats not stopping me from being here...seeing as how i did own a VW for a while!)
-Only because i live in alberta and we are truck guys out here!

Stereo Setup Sold with Jetta- However install in truck is starting to get into motion.
-ALL JL AUDIO, 2-12W3 subs, 1500W TMA Monoblock, 400W TMA fourchannel, 2 Sets of components, with Double din touchscreen and GPS ALL CUSTOM
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post #3 of 3 (permalink) Old 11-28-2008, 07:14 AM
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The thermostat stuck open would also cause the engine to not warm up properly. OP: what kind of mileage are you getting, has it gone up, down, or stayed the same?

Something you can try is to add MORE coolant (if it needs it). This time though, turn your heater to full blast, blower fan as well. With the engine at idle, add more coolant to the reservoir, but sit in the cabin and rev the engine up to 3k (wait at least 5 minutes before rev...let the engine warm up slowly first). Hold it there for a few minutes and watch the temperature gauge go up to 1/2 way. The heater should be blowing very hot at this point. Check to make sure coolant is making it to the heater core by squeezing the heater hoses going into the firewall (directly behind the transmission bell housing). Also, after a few minutes of the engine at idle, the heater core hoses should feel hot to the touch. If not, then something is blocking coolant from entering the heater core.

The purpose of revving to 3k is to force the water pump to pump into the heater core. I had to do the same thing to get my heater core working, now it blows so hot, I have to keep the heater at 1/2 way, even that is too hot sometimes.

So try that before you change out the thermostat. If, while doing this, the engine doesn't seem to ever get to 1/2 way, then I would say the thermostat is to blame.

Let us know what you find.


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