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31 votes
Accepted

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....
Jupiter's user avatar
  • 3,187
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....
Zaid's user avatar
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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 ~...
jensgram's user avatar
  • 719
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 ...
zipzit's user avatar
  • 6,559
7 votes
Accepted

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. ...
vini_i's user avatar
  • 16k
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 ...
RoboKaren's user avatar
  • 278
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 ...
PeteCon's user avatar
  • 8,702
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 ...
Eric Urban's user avatar
  • 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 ...
tlhIngan's user avatar
  • 12.2k
5 votes
Accepted

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 ...
dlu's user avatar
  • 14.5k
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 ...
Nick C's user avatar
  • 28.8k
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 ...
GdD's user avatar
  • 16.4k
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 ...
Mysterfxit's user avatar
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 ...
Giles's user avatar
  • 41
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. ...
DucatiKiller's user avatar
  • 32.9k
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 ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
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 (...
motosubatsu's user avatar
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 ...
Solar Mike's user avatar
  • 34.7k
3 votes

2012 chevy equinox blows hot air even shut off

This feels like a broken blend door. A blend door controls how much air is allowed to flow past the heater core, or past the a/c evaporator. A broken door means that air physically stuck going past ...
Lynn Crumbling's user avatar
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.
HandyHowie's user avatar
  • 25.2k
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 ...
zipzit's user avatar
  • 6,559
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 ...
race fever's user avatar
  • 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 ...
DIY-Eric's user avatar
3 votes

2006 Subaru Forrester overheating and no heat

OK - I see from your comment above that the overflow tank is still full. In most cases, if you have a blown head gasket, you'll be losing coolant. In can go into the main crankcase, in which case ...
philbrooksjazz's user avatar
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.
DucatiKiller's user avatar
  • 32.9k
3 votes
Accepted

Why is there no air flow thru my heater core?

Air flow in the heater box is not in the direction I originally thought. Having found a diagram, I was able to determine the air is passed thru the AC evaporator core all the time. Then, depending ...
CharlieRB's user avatar
  • 9,025
3 votes

foreign object in windshield vent -dangerous?

I used to work as a design/ quality/ manufacturing engineer for an automotive company. I once worked on a car that the owner complained had a premature airbag deployment. Myself and a couple of safety ...
zipzit's user avatar
  • 6,559
3 votes

Should car heater be working when engine is on but I am not driving?

I am guessing that you have an air pocket in the cooling system. When the cooling system/ engine was replaced they did not remove all the air. While the car is at idle the coolant flow is insufficient ...
mikes's user avatar
  • 19.9k
3 votes
Accepted

Can you "warm up" an electric car in icy weather?

Your question about being plugged into a charger is an important one. Most (all?) EVs today permit "pre-climate" control in which the vehicle remains connected to the EVSE and will run the air ...
fred_dot_u's user avatar
  • 4,455

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