JosephT Posted January 17, 2006 Share Posted January 17, 2006 Hey guys, I just purchased an 93 LS400 and noticed that when driving for an extended period of time after about and hour or 2 the heat will start to blow cold and hot. What could be causing this? Its 20 degrees Fer. and it can be a major annoyance. Plese help! Quote Link to comment Share on other sites More sharing options...
nc211 Posted January 17, 2006 Share Posted January 17, 2006 I assume you're not on "auto" with the tempurature setting? Hey guys, I just purchased an 93 LS400 and noticed that when driving for an extended period of time after about and hour or 2 the heat will start to blow cold and hot. What could be causing this? Its 20 degrees Fer. and it can be a major annoyance. Plese help! Quote Link to comment Share on other sites More sharing options...
JosephT Posted January 17, 2006 Author Share Posted January 17, 2006 It is not on auto, i've tried all the setting, like i said be4 its fine for the first hour or 2 then it just starts to kick back and forth from hot and cold. If i shut the car off and back on it doesnt fix it. I let the car sit for 2 hours and its back to normal. Its only on long distance trips that this happens. Starting the car in the morning it heats right up w/ no problem. Im clueless... I assume you're not on "auto" with the tempurature setting? Hey guys, I just purchased an 93 LS400 and noticed that when driving for an extended period of time after about and hour or 2 the heat will start to blow cold and hot. What could be causing this? Its 20 degrees Fer. and it can be a major annoyance. Plese help! Quote Link to comment Share on other sites More sharing options...
nc211 Posted January 17, 2006 Share Posted January 17, 2006 Hmmm....now this is a first in my book. I wonder if you have a faulty interior thermostat.. By the ignition, do you see a little square with a few rectangle holes? If so, is it dirty? Might take a toothbrush and gently clean out the holes...I've heard of that getting dirty and malfunctioning. Other than that, I'm at a loss my friend..sorry. by the way...welcome to the club! Quote Link to comment Share on other sites More sharing options...
JosephT Posted January 18, 2006 Author Share Posted January 18, 2006 Thank you, i'm going to replace the thermo. and see if that changes anything. Thanks again! Quote Link to comment Share on other sites More sharing options...
wwest Posted January 18, 2006 Share Posted January 18, 2006 Temporary fix: Turn it to max heat, turn the A/C off, use fresh airflow mode, footwell airlfow mode, and then use the blower speed to regulate your comfort level. Max heat position over-rides all sensors and just configures the system for max reheat of the incoming airflow. Quote Link to comment Share on other sites More sharing options...
JosephT Posted January 18, 2006 Author Share Posted January 18, 2006 Well then the problem might be bigger than a thermo. b/c i've done what you just stated. ;) Quote Link to comment Share on other sites More sharing options...
RFeldes Posted January 18, 2006 Share Posted January 18, 2006 Isn't that indicative of air in the cooling system? Quote Link to comment Share on other sites More sharing options...
wwest Posted January 19, 2006 Share Posted January 19, 2006 " I've done what you stated..." Who? Quote Link to comment Share on other sites More sharing options...
ArmyofOne Posted January 19, 2006 Share Posted January 19, 2006 (edited) Isn't that indicative of air in the cooling system? it could be your air compressor for the A/C is seizeing. the clutch has failed...and its cycling on and off trying to figure out why the compressor is stuck on. replace the a/c clutch/compressor. the coolant system is automaticlally bled, it has a hose on the cap of the tank, a vent hose, for that exact reason :) air bubbles will work their way out after awhile. Edited January 19, 2006 by ArmyofOne Quote Link to comment Share on other sites More sharing options...
RFeldes Posted January 19, 2006 Share Posted January 19, 2006 Good point Army, and food for thought....my point was check the radiator coolant level..because if it it low it will also show these symptoms. Also the thermostat and or the water pump which could be verified by watching the temp gauge when the surges occur. These are the simpler solutions, which we all hope for, then its onto Army's solution and beyond that an ecu or servo motor. I would start with a complete flush and thermostat replacement as it is just good maintenance. Especially in the winter when these symptoms seem to crop up. Quote Link to comment Share on other sites More sharing options...
JosephT Posted January 19, 2006 Author Share Posted January 19, 2006 I had a complete flush 2 days after I bought the car (2 weeks ago) , didn't have thermo replaced so i'll be doing that this weekend, hopefully replaceing the thermo will fix the isssue. Thank you guys Quote Link to comment Share on other sites More sharing options...
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