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Low Coolant light

Anyone familiar with 2001 Mercury Sables? I recently have gotten to use a 2001 Sable that is a perfectly great car. Low mileage, (43,000) fully loaded etc. However, it was obviously not driven very much, once a week back and forth to the beauty shop, but it was not garaged… mostly parked under a carport or a tree. What keeps happening is the Low coolant light comes on after it has been driven a while. The car has been checked out, and the coolant levels are fine… that’s easy to see… no leaks were found. Recommended repairs were Trans Flush, Belt, and Fuel Injection service. I have noticed that after the light comes on the AC stops working as well on the Max setting and I lose fan speed adjustment ability. The way I know that is because when I turn the AC to AUTO and the fan on high, it blows harder. I have also noticed that after driving it with the light on, when I stop the car I can smell radiator fluid - but I haven’t spotted any leaks - but I haven’t looked very hard because mostly I just stop driving it. Any ideas what may be causing the light to come on? Is it actually related to the AC, or is that a separate problem, OR is it a computer problem? Has there been a recall on this? Is it something that I need to worry about?

The Sable you’ve recently gotten to use may be a “perfectly great car” now, but it won’t when you’re finished with it.

The coolant light is not related to the AC. They are separate issues.

Have you ever heard of “paragraphs?”

Thanks for the constructive insight. Very helpful.

(notice the Paragraph?) The reason I am asking for advice is because I would like for it to STAY a good car. Whenever the light comes on I park the car as quickly as possible. There are times when I can drive it all day and the light doesn’t come on, and then again other times when it takes only a few minutes of driving to come on and even after sitting for several hours (minimum of 3 hours) upon driving again the light comes on within a few minutes.

I am aware that the cooling system and the AC system are two separate systems, but I wanted to give all observed issues so any relevance could be taken into account. Specifically - The coolant system has been checked out. The AC has not. The AC is acting like it is possibly a switch, or electrical problem. The fact that the fluid levels are fine and the radiator system has been checked out as ok, and that it has only been the LIGHT that has been coming on, along with the fact that there is the weird AC issue made me wonder, as I said, if it is possibly a computer problem. That is the only reason why I mentioned the two together.

If by writing that the car won’t be a great car after I am finished with it you are trying to let me know something about Sables in general not being worth the effort please elaborate. If, as I suspect, you are voicing a judgment of me as a driver - you can keep your comments to yourself. I am looking for help, not critique. This car is my mother’s car and it is going to go back to her. I want her to be driving a reliable car and not wind up stranded some place.

Very nicely done. Truly, there’s little excuse for not being at least semi-professional, failing that, nice. Top 20 contributor or not. I suspect, as you suspect, that you are correct. :slight_smile:

Most of what you describe sounds electrical (to me). Not knowing a heck of a lot about Sables, I’d see if there are any stored codes in the computer, and get the computer checked out. Freakish things happen when computers decide to go all wonky, and they’re extremely difficult to trace, if it’s not eliminated as a source of the problems.

The one item that’s concerning is the fluid smell. That tells me the fluid’s bleeding somewhere. It may be a very small leak, pinhole, even, and it may take a long time for the fluid to go down noticeably. It may also be leaking onto something that’s cooking it, and that’s why you smell it…although why it’s not a constant, I cannot fathom a guess. I know they can do pressure tests on systems to see if there’s something imminently about to fail. You may try that route.

Good luck…

Something that just occurred to me…Check for critters. Some of them like to eat plastic, and generally just chew on things. Since it sits outside, near and/or around trees, you may even have some kind of ant infestation or other “visitor”.

Have seen a lot of coolant level sensors located in the coolant tank hang up causing the low coolant light to come on. The only real fix is to replace the tank. There could be a strategy programmed into the PCM to kill the A/C if any kind of problem occurs with the cooling system. That rating has nothing to do with automobile knowledge, just how much someone has responded. Gotsta feel impotent!


It sounds as if the vehicle is overheating on you occasionally. The electric cooling fan is designed to come on when the coolant/antifreeze reaches 215 degrees. The electric cooling fan is supposed to come on automatically whenever the A/C is as well. Some fans have two speeds as well. If the fan is not working at all or the highest speed is not working, the vehicle can overheat. Under normal driving conditions without the A/C on, it may be fine as long as you are moving and airflow is coming through the radiator. As far as the A/C quitting when this happens, there are two pressure switches for the A/C system. The pressures in the system may get too high due to the lack of airflow though the condensor assembly (in front of radiator). The switches are designed to shut-down compressor to prevent further damage. Several things to check for cooling fan problems. Fuses, relays, a/c or coolant switches, wiring, fan controller, or even a engine control module. Hope this helps and good luck.

Skip the fuel injection service: a waste of your money.
Don’t get the trans flushed. Get the pan dropped, fluid and filter changed. Make sure they use the proper fluid that Ford specifies.

How was the coolant level checked? It is very possible for the reservoir to be showing full and there be air inside the engine’s water jacket. In a properly functioning system, the expanding hot fluid would push past eth radiator cap and into the reservoir and then be drawn back into the engine when the engine cooled, but if you have a leak in the engine itself (such as in the water pump) it could pull air back into the system when it cools as well as pulling coolant back in.

On this engine, the water pump is I believe driven by the the acessory belt (the engine has a timing chain) and if the water pump is leaking it could leak onto the belt driving the AC compressor and cause the AC system to stop working (that compressor belt needs good traction) as well as causing coolant smell, coolant loss, and a path for the engine to draw air into the system when it cools. As a metter of fact, the engine could even be breathing in and out of the leak and the level in the reservoire remain stable.

I think the level in the radiator (ignore the reservoire) needs to be verified, the system needs to be pressure checked and a close look taken at the possible leak places. A dye might even be appropriate.

The good news is that you’ve had the good sense to stop driving when the light illuminates. That probably kept a simple leak from becoming a destroyed engine.

Post back with the reaults of the test. We care.

Thanks, hadn’t thought of that. We are in Texas and Fire Ants love to eat the electrical insulation around wires. Many an AC compressor outside a house has bitten the dust due to ants at first being drawn to the condensation run off, and then the insulation.

Thanks everyone. This is very helpful. Now I know where to focus when we take the car to the garage. My brother has been trying to oversee Mom’s car but really only knows how to SELL you a car. I know more about cars than he does - which should give you a good idea about how much he knows. I’m forwarding this information to him so if he takes it back to the garage he knows what to tell them to look for.

I have a 99 Taurs that has had similar problems. If you have flushed the coolant and are still getting the light coming on then it most likely is the switch in the tank or the connection to the switch under the tank. A replacement tank is $25-$40 at a parts store and very easy to change. As far as your A/C goes, it may be low freon oil. Again, a simple fix, $25-$40 at a parts store for a recharge can with guage will get you back up and running. Many of the parts stores have on-line repair guides that should help in your repairs.

Okay! I took the car back to my brother and I finally spoke to him and found out what the problem was. The sending unit needed replacing. It sent the information that there wasn’t enough coolant which made the computer shut off the ac so the car would not over heat. Thanks for all your input!