My 2004 Sebring heater only blows warm air when the car is moving. If I stop at a traffic light or put it in park it blows cold air. Any ideas?

Low freon will cause the compressor to short cycle, when the compressor runs the pressure in the low line is pulled down and the low pressure switch turns it off. Not running the pressure builds up and turns it back on. In the old days there was no low pressure switch, with no freon to carry the oil the compressor was destroyed.

could be a thermostat sticking at times or a heat sensor relay ..I am willing to bet if you change the thermostat it will solve this

If your engine temp reads warm then your heater core is clogged. Try flushing the system. If it reads cold then u need a new thermostat

the heater cre needs replacing replace it and enjoy heat again

hi there it sounds like the matrix has gone it is at the back of the centre panel at the bottom when the engine is hot touch the matrix to see if its warm

One of two things has happened. Either your coolant has gotten really low (easy enough to check) or you heater core is starting to plug up.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Cooling fans working? If you notice the air getting warm mostly while stopped, probaby cooling fans not turning on. if the fans are working properly, may be low on freon and need a recharge.

If the engine temprature does not reach the normal level as it used to, it may be the coolant thermostat.

Iif it does, it could be air diverter gates not working properly, cold air blowing at a a light could point to that. The diverter gates are located under the dash.

It also coul be the valuve that controls the water to the heater core, but unlikely cause of the cold air at a light.

water pump

Sounds like a thermostat sticking. Some things to do. First check coolant level is up and moving. Second (most likely), change thermostat. Very easy fix for backyard mechanic. Make sure to put thermostat in so water flow is correct direction. Look for arrow on side of thermostat. Next, is belt to water pump loose. Another easy fix in most cars.