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Thread: Cooling (possible thermostat or otterstat issue)

  1. #1
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    Cooling (possible thermostat or otterstat issue)

    Had my radiator replaced recently, and my cooling problems seemed to go away. However, just today I noticed something odd in that when I was parked, my cooling fans weren't turning on at 220 (they usually turn on before then) but my temperature gauge didn't seem to go any higher than that, even after a minute or two of waiting to see what it would do. I turned on my a/c, the cooling fans turned on, but then off a few seconds later. The weather is about 55 degrees at the moment, if that has any bearing.

    Ideas?

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    Senior Member DMCVegas's Avatar
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    It is possible that in cool enough weather that your fans will not turn on. You've got a new radiator with no blockage, and about 18' or cooling pipes that the water has to flow through, constantly leaching heat out as the coolant flows through them. The fans are meant to be supplemental to increase airflow when the vehicle isn't moving fast enough. In the fall through early spring on a year round daily driver, it was very rare for my fans to turn on.

    The only way you'll be able to test things is if you trigger the fans manually, and then pull the otterstat to test it in hot water.
    Robert

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    Senior Member Chris 16409's Avatar
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    Did you make sure to bleed the radiator? Air can become trapped in there as well.
    Chris Miles

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    I didn't install the radiator myself, my mechanic did it for me.

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    The 2nd part of your post regarding the A/C being on and the fans coming on with it, makes me think it is an otterstat problem.

    Anytime the A/C compressor is engaged (compressor clutch snaps in), the cooling fans upfront should turn on. Then, when the air conditioning compressor cycles off, the cooling fans shut-off. This is normal and in cooler weather where there isn't much air cooling to do, the A/C compressor will not stay on for very long.

    The other way your cooling fans are meant to come on is via the otterstat. Sounds like that portion isn't working as intended.

    Tell me, what were your cooling system problems that led you to replace the radiator? Not assuming this wasn't a good or necessary thing to do, but perhaps it wasn't the thing you needed to do to get it resolved?

    You can test the otterstat functionality pretty easily by jumpering the wiring harness side of the two leads coming to the otterstat together and seeing if the cooling fans turn themselves on. Engine doesn't even need to be running to test it this way, just have the key in the ignition and turned to accessories.

    Picture of the otterstat and where to jumper it is here: http://dmctalk.org/showthread.php?10...l=1#post166051


    Sept. 81, auto, black interior

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    Quote Originally Posted by Jonathan View Post
    The 2nd part of your post regarding the A/C being on and the fans coming on with it, makes me think it is an otterstat problem.

    Anytime the A/C compressor is engaged (compressor clutch snaps in), the cooling fans upfront should turn on. Then, when the air conditioning compressor cycles off, the cooling fans shut-off. This is normal and in cooler weather where there isn't much air cooling to do, the A/C compressor will not stay on for very long.

    The other way your cooling fans are meant to come on is via the otterstat. Sounds like that portion isn't working as intended.

    Tell me, what were your cooling system problems that led you to replace the radiator? Not assuming this wasn't a good or necessary thing to do, but perhaps it wasn't the thing you needed to do to get it resolved?

    You can test the otterstat functionality pretty easily by jumpering the wiring harness side of the two leads coming to the otterstat together and seeing if the cooling fans turn themselves on. Engine doesn't even need to be running to test it this way, just have the key in the ignition and turned to accessories.

    Picture of the otterstat and where to jumper it is here: http://dmctalk.org/showthread.php?10...l=1#post166051
    I was told months ago that my radiator would have to be replaced soon. I could drive on the highway no problem with the air flow keeping the engine cool, but when I got to a stop sign or light, the temperature gauge went up despite the cooling fans kicking on. It got worse, so that necessitated my radiator change out. Luckily, the shop I take my car to is dependable, honest and doesn't bleed people dry. I'll have to look into checking my otterstat, to be on the safe side. I don't need any special tools?
    Last edited by Fluxn83; 10-30-2017 at 05:24 PM.

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    Quote Originally Posted by Fluxn83 View Post
    I was told months ago that my radiator would have to be replaced soon. I could drive on the highway no problem with the air flow keeping the engine cool, but when I got to a stop sign or light, the temperature gauge went up despite the cooling fans kicking on. It got worse, so that necessitated my radiator change out. Luckily, the shop I take my car to is dependable, honest and doesn't bleed people dry. I'll have to look into checking my otterstat, to be on the safe side. I don't need any special tools?
    Not to test the otterstat, no. You literally just need a short piece of wire. A paperclip maybe even if you can get it to stay in place. All you are trying to do is simulate the otterstat being closed, which completes the electrical circuit and tells the cooling fans to turn on.

    Park the car. Put the parking brake on and/or chock the wheels (with a piece of wood if need be). Don't need it rolling onto you or your helper.
    Put the key in the ignition and turn it to accessories. You don't need the engine running to do this test, only power to the electronics.
    Turn the HVAC mode selector knob to something other than A/C. Put it at OFF if you'd like. We want to make sure it's not the A/C turning those fans on as we focus on the otterstat.
    Reach up from underneath and disconnect the otterstat wires. Then jumper those two wires together, either with a short piece of wire or just hold them together directly. Your cooling fans should both come on at this point.
    Report back what you find.


    Sept. 81, auto, black interior

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    Quote Originally Posted by Jonathan View Post
    Not to test the otterstat, no. You literally just need a short piece of wire. A paperclip maybe even if you can get it to stay in place. All you are trying to do is simulate the otterstat being closed, which completes the electrical circuit and tells the cooling fans to turn on.

    Park the car. Put the parking brake on and/or chock the wheels (with a piece of wood if need be). Don't need it rolling onto you or your helper.
    Put the key in the ignition and turn it to accessories. You don't need the engine running to do this test, only power to the electronics.
    Turn the HVAC mode selector knob to something other than A/C. Put it at OFF if you'd like. We want to make sure it's not the A/C turning those fans on as we focus on the otterstat.
    Reach up from underneath and disconnect the otterstat wires. Then jumper those two wires together, either with a short piece of wire or just hold them together directly. Your cooling fans should both come on at this point.
    Report back what you find.
    Found the otterstat and wires, wasn't really able to hold them together to jump. Awkward angle. I'll try later with a wire or paperclip. I'm assuming if it doesn't work, then the otterstat is bad?

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    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by Fluxn83 View Post
    Found the otterstat and wires, wasn't really able to hold them together to jump. Awkward angle. I'll try later with a wire or paperclip. I'm assuming if it doesn't work, then the otterstat is bad?
    If you jumper it and the fans turn on then most likely your otterstat is bad. But you may have an intermittent connection somewhere so it may work or not sometimes. Or like others have said if you have an air bubble at the otterstat that would stop it from turning the fans on. Is your otterstat pointing down? If it points up that can trap air on it.
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    Quote Originally Posted by Bitsyncmaster View Post
    If you jumper it and the fans turn on then most likely your otterstat is bad. But you may have an intermittent connection somewhere so it may work or not sometimes. Or like others have said if you have an air bubble at the otterstat that would stop it from turning the fans on. Is your otterstat pointing down? If it points up that can trap air on it.
    I believe its pointing down. How would I tell, if the prongs from the otterstat that the wires connect to are going down? If thats the case, its pointing down.

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