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30 votes
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Why would a mechanic crank heater to maximum

If the cooling system is drained, it needs to be refilled and all air needs to be removed. The mechanic turns the heater on to allow coolant through the heater core to be sure all air is being removed....
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  • 2,522
11 votes

Car overheats idling in traffic

My top suspect would be a radiator fan that isn't running when it should. The fans assist in transferring heat from the radiator to the surrounding air, and are most needed when the car is stationary....
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9 votes
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What is more economic to run? Pre-heater or the engine itself?

Let's do a little back-of-the-envelope calculation: Assuming that the heating unit has an efficiency close to 1.0 and that automotive diesel has an energy density of ~39 MJ/l which translates to ~...
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9 votes

Can running the heater with the A/C on damage your car?

No way. In fact the system is actually designed that way. The Air Conditioning (A/C) system on your car runs automatically when you are in the Defrost mode. Like you say that setup removes water ...
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7 votes
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Excessive Coolant Expansion: Part 2

It's possible that the impeller blades on the water pump are either compromised or gone completely. I ran into a somewhat similar situation with a Chrysler. The engine would not overheat driving. ...
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7 votes

Keeping windshield ice-free without heater

Does the air conditioner work? If so, you can blow COLD and DRY air onto the windshield from inside by setting the controls to: A/C, WINDSHIELD, OUTSIDE AIR. The cold/dry/outside air from the A/C ...
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  • 278
5 votes

How long should I wait to turn on my rear defroster during the winter time?

If you mean the rear defrosting wires in your rear window, you should be able to turn it on immediately as it's electrically based. If it's making a noise, I suspect it's the circuit breaker that ...
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  • 2,674
5 votes

Why does my car sometimes blow cold air while the heater is on?

Does your car overheat too? If so, you could have a faulty thermostat, an air pocket in your cooling system or maybe even a leak somewhere. My truck's heat would only work while I was driving, then ...
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5 votes
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1996 Rav4 not warming up properly when driving and heat not hot

If the thermostat is stuck open, you would get the symptoms you describe. A thermostat stuck closed will cause overheating.
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5 votes

2006 Subaru Forrester overheating and no heat

Check the overflow tank on the radiator when the car is overheated. If that tank is full, you've probably got a blown headgasket - that's how I spotted mine. For the thermostat; did you buy an OEM ...
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5 votes

Heater problems in 2001 F150

Coolant flow through the heater core is restricted, which means the fan is able to cool off the water in the heater core before it is replaced with warm water. There are a few possible causes for ...
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  • 1,286
5 votes

Should I use the heater while warming up my car?

Well, this is a question for a Canadian guy. Here's the thing: in extreme cold (-20C and colder), the moisture coming off your breath will condense as ice and fog on the inside of your windows. Air ...
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5 votes
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Should I use the heater while warming up my car?

You are right that the heater in internal combustion engine powered vehicles usually uses the waste heat of the engine for heating – that's why in the summer you can use the heater to get a bit of ...
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5 votes

Car heater taking too long to come on if at all?

When the engine was changed, was the heater properly bled when the cooling system was refilled? If there is an air-bubble stopping coolant from flowing properly through the heater, that would create ...
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  • 28.6k
5 votes

How do race drivers clear foggy windscreens?

Fogging happens when there's a temperature differential between one side of the glass and the other. Most racecars are open - they remove the windows to save weight too, so the temperature inside the ...
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4 votes

How often to start/drive a vehicle to keep it healthy?

It depends on the vehicle, why it is being left, and how it is prepared before being left. If it's a vehicle that's in reasonably regular use, then I'd recommend making sure it's used at least once ...
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4 votes

Car overheats idling in traffic

I had a similar problem with my 2000 Ford Focus last year. I can't remember what it was called, but basically it's a thermostat that's sits against your radiator that turns on the radiator fans when ...
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4 votes

Car overheats idling in traffic

I had a problem with my VW Golf overheating. I also changed various parts, the thermostat being the first as that controls the circulation of the coolant. In the end I found the cause, the system ...
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4 votes

2006 Jeep Commander - heater is only blowing hot air

bad air duct door You have multiple air duct doors in your car. One of them will control the air from your heater. You may have situation where the servo motor is bad in a particular door. ...
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  • 32.7k
4 votes

Keeping windshield ice-free without heater

The easiest thing you could use right now is a de-fogging agent. Anything which will keep the humidity off of the windshield. What I'm talking about is something like Rain-X. At least this should keep ...
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4 votes

Car heater taking too long to come on if at all?

In addition to Nick C's excellent suggestions there is also a possibility that the thermostat is stuck in the "Open" position - this would mean that coolant is always circulating around the radiator (...
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  • 9,674
4 votes

What is more economic to run? Pre-heater or the engine itself?

Just look at the possible efficiency : you leave the main engine on idle just for the heater - it is not the most efficient at that speed : better under load at say 2000rpm. The pre-heater is doing ...
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  • 34.4k
3 votes

2004 V8 LT Chevy Suburban No Heat at Idle

You need to purge your cooling system. Raise the front of the vehicle with a jack or ramps. Driving up a sidewalk works too. With the engine cool (when you touch it it should be cold): Remove the ...
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  • 3,363
3 votes

2006 Jeep Commander - heat problems

If you haven't done this already, check your antifreeze levels of your overflow and radiator when cool. Make sure both are full. Often times, there can be an air lock preventing antifreeze from ...
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3 votes

Dodge Ram blower motor works intermittently

I had this problem with an 2004 Caraven turned out to be a bad ground installed ground wire directly from Motor works fine now
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3 votes
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2011 Chevrolet Equinox: Heater blows cold air when set to defrost mode

The reason this occurs is to take care of the humidity in the vehicle while your defroster is running. MANY older vehicles have this as a common function when your defroster comes on. It's odd though ...
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  • 3,323
3 votes

Pacifica heater core hose reconnect

OP Resolved the Issue flow direction was not an issue. OP reconnected hoses and stated the issue is now closed.
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  • 32.7k
3 votes

Mysterious honda civic 2002 overheating some time

I'm in general agreement with Ben. Cooling fan not working. The description of high vehicle speed = okay and low speed not means your fan isn't working for you. This could be a problem with fan ...
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  • 6,419
3 votes

Mysterious honda civic 2002 overheating some time

I would check the water pump, it sounds like the blades may have corroded away. From your description it certainly sounds like the water isn't circulating.
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