It could be that the thermostat needs to be replaced.
I recommend you take it to an AskPatty Certified Female Friendly Repair Shop and have them diagnose the problem and fix it. Not having any heat will be a big problem in the coming months now that we are headed into Fall & then Winter.
〉 Answered on Sep 9th, 2013 by Amy Mattinat, Owner and Author at Auto Craftsmen Ltd
May be the heater blend door or an issue with the dashboard controls. If your adventurous , locate the heater hoses under the hood. There will be 2 going thru the firewall of the car if they are hot it is a heater control that is failing
〉 Answered on Sep 9th, 2013 by Barb Petrey, President - DBK Enterprises Inc at Jiffy Lube
Check your coolant level (when the car is cold) at the radiator, not just the reservoir. If the level is full, see if both heater hoses get hot (and they should be hot) after the car has been running for a little while. If the coolant is low or the heater hoses are not hot, you have a cooling system issue that needs to be fixed asap. If both hoses are hot and the level is good, you may have a blend door control issue. A good repair shop should be able to diagnose either case.
〉 Answered on Sep 9th, 2013 by Helaine Kurot, Owner/Technician at 360 Automotive
Kristin, About your 2001 Lexus, It sounds like the blower motor is working. It may be a bad heater switch (the one on the dash) or one of the blend doors (inside the dash) may be broken.
〉 Answered on Sep 9th, 2013 by Maryann Croce, Owner at Croce’s Transmission Specialists
It sounds like there may be a problem with the blend door. This is a door found in the dash that diverts the air between the cold air to the hot. It may be a mechanical linkage, a vacuum hose or an electrically controlled door. The fix may be relatively easy, but the labor into getting to the door could take some time, depending on the vehicle.
〉 Answered on Sep 9th, 2013 by Suzanne Grego, Technician at City of Philadelphia Fleet Management