QuestionMy 1998 lxi is over heating but faster when i put the ac on. I have changed the therm but still is overheating. I got a diagnostic done but everything came back fine.Do you know what else this could be?
AnswerHi Tonya,
The decrease in cooling ability might be due to an impeded coolant flow across the tubes of the radiator. The flow is from the passenger side to the driver side and then back. One way to tell if the radiator is clogging up is to touch the passenger side tank of the radiator and compare that to the temperature of the tank on the driver side of the radiator, after having driven it long enough to be up to temperature. If it is flowing well it should feel about equally hot, but if it is much cooler on the driver side that would indicate a restricted flow which would suggest that you have the radiator flushed out.
There also could be a build-up of leaves and dirt on the fins of the radiator so check that by putting a light behind the radiator and look through from the front to see the openings aren't blocked.
Finally, as the temp rises above 1/2 point on the gauge, stop the van and make sure the radiator fans are coming on. They operate at two speeds and should move faster the higher is the temperature gauge.
It might be that the temperature sensor mounted next to the thermostat housing is inaccurate. That could be checked with an ohmmeter placed across its two connector pins which should read under 1,000 ohm when the gauge is 1/2. The laboring of the AC compressor as the pressure in that system rises should also provoke the fans to move at higher speed.
Let me know what you observe and we can go from there.
Roland
