I have had intermittent overheating problems with my Taurus. It began last summer and is now happening again. I have flushed cooling system and changed thermostat twice. I just put in a new water pump and belt and am still having issue. Then this weekend I had a thought, both fans are always running. I was told these are two speed fans with a relay the moves the speed up and down to boost cooling. When it is over heating this last time but is appears they are on low speed. A few minutes later they seem to be running on high speed. Do I just replace the relays or can I test them? Is it more likely the relays or the fans?
If the fans change speed, then nothing’s wrong with the relays or the fans.
Explain what you mean by overheating.
Tester
The temperature gauge starts to climb on days like yesterday when it is running 99 outside. We are running AC full blast and then the gauge slowing starts (few minutes) to climb from normal range (about 3:00) towards the red zone, just before hitting red zone, the AC is turned off by computer and I turned heater full blast and opened windows to save my engine. Does not make my wife too happy. It never boiled over if that is what you are asking. At this moment I opened hood and heard normal fan sound. I turned it off, fueled my cars and when I started it 5 minutes later it was running normal temp and the fans were running at a much higher speed. That was why I tried to turn car off and on when it started to creep a while later but I could not get fans to run faster again…
The first thing to check for is excess road debris on the front of the condenser. If that appears to be fine, then you may be looking at a partially restricted radiator where it isn’t able to cool the engine off fast enough when the ambient temperature increases.
The radiator can be tested for restriction by pointing an infra-red thermal gun at the radiator to see if there are any cold spots.
Tester
I guess your recomendation is to replace ther radiator then? I do not happen to have a infared thermal gun and if it is obstructed I hear no one rods radiators any more or power back washes them either. Radiator Barns sells one for $110, sounds like my best option?
:o)