Chrysler Repair: heater gets hot only while driving, heater coils, degree thermostat

Question
i was wondering what would cause my heat to only get hot while driving. When the car is idle the air blows cold. I noticed this problem started  when a friend replaced the power adapter outlet. I didn't know if he could have messed up wiring or fuses to cause this problem. The heater blower works but is really loud when turned all the way up . I would appreciate any suggestions. Thank you!

Answer
Hi Tonya,
I don't see any relationship between the power outlet and the heater output. What does the coolant temp gauge on the dash show? If that gauge is staying on the cold side (below 1/4 scale) when you are idling and it only rises when you are driving then the thermostat housing may be stuck open such that the system is being 'overcooled' which of course means the water going into the heater coils is cooler than it needs to be. So compare the gauge to the heater temp output and if the gauge on the dash is not running at least 1/4 scale then I would look at the thermostat to see if it is indeed stuck open. It also may be that in earlier days when the car ran too hot in the summer that the thermostat was removed or a thermostat with an opening temp of 180 was put in instead of a 195 degree thermostat. Do you recall any such problem/service being done?
When you write back tell me the year/make/model/engine (L) of the vehicle.
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Thanks,
Roland