1999 Chevy Venture Temp overheating, but no heater

Tiny
MAELSTROMMAGE
  • MEMBER
  • 1999 CHEVROLET VENTURE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 174,000 MILES
On the first cold day of winter (below freezing) our van temp gauge pegged out into the redzone and the warning light came on. However, the heater was not blowing warm air at all.

We took it in to a local shop and they could not repeat the problem. Carbon dioxide test came back negative. The shop did not want to change the thermostat because they had no idea what was wrong with it.

I picked the van up after work on a Friday and it touched the redzone on the way home. I had read something about there being two relays for the fans, so I tried turning the air on to override one of the relays and the temp started to drop immediately. However, still no heater. Monday got up early to fill the van up and check it out, it never overheated on the way to the gas station, but came very close. Still no heater.

I can find a lot of complaints about Chevy Ventures like this on the interent, but no one has posted a solution.
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Monday, December 14th, 2009 AT 7:23 AM

6 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Okay, this can be caused by several things. First, make sure the coolant is full. Also, let me know if the car overheats when you are at highway speed. Next, with the engine running, hot, and the heater on high, feel both heater core hoses. Both should be hot. Finally, check to make sure there is no coolant getting into the oil.

As far as the fan, does at least one turn on when you overheat?

Have you had to add coolant?

Joe
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Monday, December 14th, 2009 AT 7:55 AM
Tiny
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Coolant is full. No coolant in oil. Will have to check the rest after work today. Although the shop I took it to told me the fans were working. But, this could be an intermittent problem.

However, on the way to work today (outside temp 41 deg F) everything seemed to work fine. Even the heater.

This is after this morning going and filling it up at a gas station and having some problems. See previous posting. I am not sure what the outside temp was this morning, but the temp is supposed to drop all day.
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Monday, December 14th, 2009 AT 8:46 AM
Tiny
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Van has worked well the last few times I drove it, until this morning. Just as I pulled into work (roughly a 12 to 15 minute drive) the temperature gauge started into the red zone. And I had no heat coming out of the vents. I parked the van and opened the hood, both fans were working. I grabbed the upper radiator hose and it was still cool. I squeezed it a few times then shut the hood in disgust. I went to turn the van off and now the temp gauge is reading normal. I opened the hood again and touched the upper hose and it was starting to get warm. The outside temp is 17 deg F.

What is going on with this thing? Can a thermostat work intermittently?
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Tuesday, December 15th, 2009 AT 8:14 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Believe it or not, yes it could be the thermostat. Infact, based on your description, it sounds like it may be sticking shut. I would try replacing it to see if that helps.

Let me know what you find and thanks for using 2carpros. Com

Joe
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Wednesday, December 16th, 2009 AT 9:24 PM
Tiny
MAELSTROMMAGE
  • MEMBER
Here is what I have done and it seems to have worked:
I drained some of the fluid out of the radiator and added straight antifreeze. I then drove it to work and on the way to work it started to climb in temperature (but never overheated).

It reached about 3/4 of the way to overheating and then dropped back to normal operating zone. It has worked fine ever since.

I noticed it was overheating only on really cold days, so I figured the antifreeze to water ratio must be off.

If anything changes in the next few days, I will updated this thread.
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Monday, December 21st, 2009 AT 5:57 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
If that seems to help, I would recommend draining it all out and replacing it with a 50/50 mixture of coolant and water. Also, if the vehicle came with dexcool coolant, make sure you dont mix it with any other type of coolant unless it is a universal coolant GO-5 that can be mixed with dexcool.

Also, when you remove the coolant, replace the thermostat. If it around a 5.00 part and it may still be the cause of the problem.

Let me know how things work out for you. THanks for using 2carpros. Com and I wish both you and your family a safe and happy holiday.

Joe
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Monday, December 21st, 2009 AT 11:17 PM

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