Why does my Van overheat when running idle?


Asked by May 04, 2012 at 07:55 PM about the 2005 Toyota Sienna XLE

Question type: Maintenance & Repair

When I run the A/C then park my van, it slowly starts to overheat. I see the temperature gauge go from the middle to hot. The air coming out of the vent also goes from cold to warm. When I put the van back in motion, it cools down and goes back to normal. Any ideas as to what is going on?

8 Answers


Your fan is most likely not working. Check to see if the fan comes on when the engine gets up to temp. If not things to check are fan relay fan fuse and wiring and the fan itself.

15 of 15 people found this helpful.

Why would the vents pump out cold air when the van is driving if the fan was not working? Is there a corolation there?

4 of 4 people found this helpful.

There are electrically operated radiator cooling fans to cool the radiator. If they don't come on, your van will overheat when it is not moving forward, to cause cool air to be forced through the radiator.

2 of 2 people found this helpful.

We are talking about two different fans. The fan that cools the engine (cooling fan) and the fan that cools or warms the interior (blower motor). The cooling fan is the one I was referring to this one is thermostatically controlled. When the engine gets up to temp the cooling fan kicks in. The fan you are referring to is the one that controls interior temp. This one runs depending on user input.

3 of 3 people found this helpful.

I have the same problem but I do notice that both engine fans are on when its hot.

12 of 12 people found this helpful.

Hey I have the same problem but I look and find out one was not working but I try to make it spin and it work again I am going to see if it doesn't stop again let's see how it goes.

1 of 1 people found this helpful.

My 2004 Toyota Sienna cue coolant gage rises when I'm at a stop light then when I go it goes back to normal.. Why is that and will it be a easy fix?

4 of 4 people found this helpful.

I'm also having this problem with my 2004 Toyota Sienna LE with about 160K miles. Had the water pump and timing belt replaced around 120K. There does seem to be a small leak somewhere in the cooling system as I have to refill a little bit (maybe a pint or two) every few months, but this doesn't seem to be a bad enough leak for me to investigate further. However, the fact that the AC air in the passenger compartment gets warm when the vehicle starts overheating makes me think it might be related to the AC compressor. When initially starting the van, we typically have some belt noise (squeeling) for a minute or two. I've tightened the belt a little once before, which helped, but then the squeel came back. So if a worn AC compressor is adding load to the engine, would that cause these types of symptoms with the AC temp in the vehicle getting warm as the car overheats? The other thing I've seen online is that the radiators get corroded after a while and need to be replaced. You have to check the temp at the top and bottom to see if the flow is adequate and whether the radiator is working properly or not. Hairline cracks in the plastic radiator sides could also be causing the small leak I'm seeing as well as pressure leaks that would cause the cooling efficiency to drop. A pressure test would probably confirm if this is the case or not. Anyone else have thoughts/comments/experience with this? Thanks!

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