96 Taurus with fluctuating heat gauge

[Kaleo]

Car had fluctuating heat gauge, took it to the shop and they say it needs a new air compressor. That the air compressor is making the water pump work off and on which is making the heat gauge fluctuate? Does anyone had similiar problems or is $1200 for air compressor ok price?

[shorod]

Welcome to the forum!

New air compressor? Did they maybe say it was a secondary air pump, or maybe Air Conditioning (A/C) Compressor? If they really just said "air compressor" I'd suggest you find another shop. Unless of course you've added air suspension to your car, but even then that shouldn't affect your engine temp.

For what it's worth, the water pump does not have an off or on, when the engine and belts are spinning, so is the water pump. The A/C compressor will cycle on and off when the system has an appropriate refrigerant charge and the HVAC system requests the compressor, such as when the A/C is turned on or the windshield defrost is turned on. When the A/C is engaged, the PCM should also activate the radiator cooling fan. The cooling fan could cause the heat gauge to fluctuate, and if the fan is not working, that could cause the heat gauge to rise when the A/C compressor is on since the compressor is putting an increased load on the engine. However, the A/C compressor coming on won't by itself cause the heat gauge to fluctuate drastically.

What kind of fluctuation are you talking about here, from N to L of "Normal" in 15 seconds? Did they check the condition of the pressure cap and bleed the cooling system to get any air pockets out? Also, it's fairly common for the water pump impeller to fail in some model years of Taurii, you can search the forum using the Search this forum feature from the Taurus forum main page.

-Rod

[tripletdaddy]

Under what conditions did your temp guage fluctuate? If you had the interior heat on, did its heat output fluctuate too? Did the engine seem to speed up or slow down with the temp fluctuations? Did the temp guage fluctuate at idle, park, stop sign, low speed driving, high speed, all times, etc? Does anything else like anything electrical not work normal when the fluctuations are present? Does it happen when the engine is cold? While you have your car parked and hood up, see if the temp dips when the radiator fan comes on and the temp rises when it is off. If you have a resistance meter, you can verify if your temp sending unit is working properly. It is 10 ohms when hot and 74 ohms when cold, measured at its top terminal with the wire removed and at ground at the intake manifold or the battery negative post.