Heater problems heater not getting hot. have flushed and put in new thermostat.

Check to see if the hot coolant is getting to the heater core. Touch both heater hoses to see if they are both hot. If not, then flush out the heater hoses and heater core.

check the controller an vacuum lines

could have air lock or heater core plugging up. heater cores should be back flushed.when car is hot touch one heater hose at a time both should be fairly hot if both hot then the problem is temp control.

If you flushed the coolant with the thermostat in, chances are you didn't flush the coolant. Regardless, it's easiest to check the controls inside first. Does the blower fan work? Does the air flow change from floor to vent, to dash as it's supposed to? Does the A/C change temps when knob is turned from cold to hot? Post results.

disconnect the heat hoses going into fire wall , put hose into one with pressure and flush as it sounds like it could be bloked in the heater core,the other thing that could be the problem be the hot ,cold switch as it restricts the flow to makes the heater hoter or colder , it might need tlc or replacing as it is manaul not elec

Put in a low temp themostat and see if this helps. Also check your mix on your antifreeze. Make sure it is 50/50 or what ever the dealer recommends.

Flushing the system and adding new antifreeze would have been my first suggestion, so, thanks for mentioning that.

We should check a couple of other things.

1. Start the engine, let it run for 6 to 8 minutes, ( with the heater off ), to allow the engine to reach normal operating temperature. Then, turn your heat and fan wide open, then listen to the engine to see if you hear a click, you should be able to hear the thermostat open up to circulate the coolant. If you do not hear a click, you may have a stuck, or partially stuck thermostat.

If the thermostat doesn't open, the hot water/coolant will not flow in to the heater core.

2. In the back of the engine, on the fire wall, locate the inlet and outlet hoses to the heater core. They are both usually about 1 inch in diameter. Carefully feel each hose. Both should be hot. If only one is hot it's because you have blockage somewhere preventing the circulation of coolant to the heater core.

The most common area for blockage is in the heater core itself. Sometimes flushing doesn't clear it out.

I hope this will help you resolve the problem.

Check your thermostat to see if it is sticking. You may need to replace it. It is located within the large hose coming from the radiator and at the engine where the bolts attach.

Well there's only part that has to do with the cooling system and serp belt - the water pump!! Maybe it's starting to seize or has too much play. Either way, when you change the water pump, replace the thermostat and flush the system very thoroughly, those 98-99's are notorious for rust build up. Make sure to pull the heater hoses off and flush the heater core too. After all said is done, purge the coolant and make sure there is heat from the blower. If not you're going to have to replace the heater core because that gets clogged sometimes when flushing.

sounds like a blend door problem... find lever to blend door disconnect it move lever back and forth and see if it changes anything...