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1990 Volkswagen Golf Heater

Tiny
RODNEYRAMSEUR
  • MEMBER
  • 1990 VOLKSWAGEN GOLF
  • 4 CYL
  • 2WD
  • MANUAL
  • 103,152 MILES
The problem is my heater only works when the car reaches a certain speed. After I initially replaced the core, the heater worked perfectly, but after a while it started doing the same thing. The only way it works is when the car is moving. If I stop or slow down it blows cool air, regardless if the motor is warm. I have replaced the heater core with a used heater core, maybe not the best move, and I replace the thermostate (new). It started out working fine but after about a month it regressed into the same old thing. Man it gets cold here in Germany. Help!


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Friday, February 13th, 2009 AT 2:19 AM

11 Replies

Tiny
2CARPRO JACK
  • MECHANIC
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Do both heater hoses get hot?If you hold the rpm's up without the car moving will it get hot then? Sounds like a flow problem, are you sure all controls under the dash are working (blend door)
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Friday, February 13th, 2009 AT 7:41 AM
Tiny
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If the car is not moving and I hold the rpms up without the car moving the heater heats up - yes. Could it be the water pump isn't functioning at 100 percent?
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Friday, February 13th, 2009 AT 8:17 AM
Tiny
2CARPRO JACK
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Could be, I have seen many of those VW 4cyl water pumps loose the impeller off theback, It is just plastic and can spin on the shaft and not create full flow
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Friday, February 13th, 2009 AT 8:43 AM
Tiny
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So in saying that, could it be the water pump only goes up to 100 percent when the car motor is being revved causing it to speed up the water being pumped through system, which in turns makes the heater work. What would be your first step in trouble shooting to fixing this problem. Also as you mentioned earlier, which hoses do I need to look at? Or how do I fix this "flow problem?
Thanks.

Sign, freezing in Germany
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Friday, February 13th, 2009 AT 9:28 AM
Tiny
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So in saying that, could it be the water pump only goes up to 100 percent when the car motor is being revved causing it to speed up the water being pumped through system, which in turns makes the heater work. What would be your first step in trouble shooting to fixing this problem. Also as you mentioned earlier, which hoses do I need to look at? Or how do I fix this "flow problem?
Thanks.

Sign, freezing in Germany[/quote:d29dd6a4ed]

So what do you suggest or recommend to fix this. The impeller or the hoses or both?
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Saturday, February 14th, 2009 AT 9:33 AM
Tiny
RODNEYRAMSEUR
  • MEMBER
  • 7 POSTS
So in saying that, could it be the water pump only goes up to 100 percent when the car motor is being revved causing it to speed up the water being pumped through system, which in turns makes the heater work. What would be your first step in trouble shooting to fixing this problem. Also as you mentioned earlier, which hoses do I need to look at? Or how do I fix this "flow problem?
Thanks.

Sign, freezing in Germany[/quote:8021dabde1]

So what do you suggest or recommend to fix this. The impeller or the hoses or both?[/Quote:8021dabde1]

Hello Jack?

What are the repair suggestions?
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Tuesday, February 17th, 2009 AT 1:43 AM
Tiny
2CARPRO JACK
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Sorry, my auto-notification isnt working. See if both hoses are getting hot. Does the engine run at the normal temp?
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Thursday, February 19th, 2009 AT 7:30 AM
Tiny
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Both hoses do get hot. I'm thinking it is the impeller on the back of the water pumb you mentioned earlier. What else can it be? If I have the car in neutral when it is sitting still, it blows cold air. If I press the gas pedal and hold it down, it starts to blow warm air. I have to be moving at a certain speed (fast) and then it blows warm air. Well Jack the ball is in your court. You are my last resort before I pay a visit to the VW specialist over here and I know he is going to take me to the bank.
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Thursday, February 19th, 2009 AT 7:41 AM
Tiny
2CARPRO JACK
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No-pressure situation. Love it. Lol If there are no heater control valves or anything that could impede flow, the only other possibility is that the blend door is moving due to lack of vacuum. Double check that the heater control valve is full open or closed. One hose should cool down when temp is selected to cold. IF not the restriction may be the valve
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Thursday, February 19th, 2009 AT 7:58 AM
Tiny
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Thanks for these quick responses, man that is quality service. What is a blend door? It is blowing air very good. The only problem is the air is cold, so how can it be impeded if it is blowing air? By blend do you mean where it blends the hot air with the cold air and this is where you select how much of what you want? Can you tell me where the blend is door so I can find it. After I find it, how do check to see if the vacuum is lacking? Also which valve were you refering to about being restricted and where do I find that? Sorry for all these questions, but you sure have a wealth of knowlege and I just need a little bit. Thanks Jack. Very respectfully.
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Thursday, February 19th, 2009 AT 8:20 AM
Tiny
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The heater valve is inline on the heater hose. You could try removing the valve and installing a coupler to see if that gets you hot air. Try that before we go under the dash. It may not be vacuum problem your temp (blend) door is cable operated. You will need to remove covers under thedash to find out where the blend door(temp) cable goes to. It can still blow air, just like if it was on heat or a/c. It is a door that directs the air through the heater core (heat) or the evaporator core (a/c)
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Thursday, February 19th, 2009 AT 8:46 AM

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