Coolant temp and A/C running in traffic....

Discussion in 'Archived Threads 2001-2004' started by Scott Strang, Jul 29, 2002.

  1. Scott Strang

    Scott Strang Screenwriter

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    I've always heard people say that one shouldn't run the compressor while in stop and go traffic due to the potential for getting the liquid too hot.

    Does the temp gauge give a pretty close representation of the entire jacket's temp? Does it vary from car to car and on where the sending unit(s) is located on the engine's jacket?

    My question is if the temp is normal (and staying below the red and never getting close) is it okay to run the A/C compressor (in a vehicle with a belt driven fan, no eletric fan) in the traffic and have to worry about overheating.

    I've never had a problem like this even in these hot Louisiana summers. But I also always check the coolant temp and my fan is driven from the engine's serpentine belt.

    Are electric fans better? I would think that the speed being independent (directly) of the engine rpm would be a plus.

    thanks all
     
  2. Steve Schaffer

    Steve Schaffer Producer

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    Scott,
    I make my living working on Toyotas at a dealership shop.

    If your cooling system is in good condition there's no reason not to use the AC in city traffic on a hot day.

    If the guage does not go up a lot under these conditions, go ahead and run the AC.

    If it does, there's a malfunction in the car's cooling system. Possibilities are partially clogged radiator, malfunctionning fan clutch, and too strong a concentration of coolant.

    Clogged radiator is self-explanatory.

    Most vehicles with engine driven fans have a device called a fan clutch which lets the fan sorta freewheel until the temp gets up to a certain point in order to save power and lower fuel consumption. When the air passing thru the radiator gets above a certain point, the fanclutch engages and the fan starts sucking air through the radiator more strongly. This is especially necessary in slow or stop/go traffic when there isn't much forward movement of the car to force air through the radiator.

    The coolant in your car should be no more than a 50/50 mix of good ethylene glycol coolant (Prestone or other major brand is ok) and clean water. Ethylene glycol both raises the boiling point and lowers the freezing point of the mixture.

    However, ethylene glycol does not transfer heat nearly as well as water does, so if you have too strong a concentration in relation to water, the engine will run too hot.

    I live in Fresno, CA, where summer temps hover between 95-105 from late June through September. In my experience any car built in the last 20 years or so with a well-maintained cooling system can be run with the AC on in any kind of heavy traffic under these conditions.
     
  3. Todd Hochard

    Todd Hochard Cinematographer

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  4. DennisHP

    DennisHP Second Unit

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  5. Scott Strang

    Scott Strang Screenwriter

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    I appreciate all of your replies.

    What you said confirmed what I suspected.
     

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