I have a 2004 Honda Civic that has about 183,000 miles.
The problem is that when I start my car in the morning, the car never totally warms up when it’s cold outside (I live in VA), until I press the gas pedal and rev the engine. Until I press the gas pedal, the temperature gauge stays at cold, and the heater blows cool air. I’ve taken it to the dealer 12 times for the same issue, but they can never find the real problem. They flushed the A/C hoses and radiator, replaced the radiator cap, installed an upper hose, installed head gasket, water pump, and while there, the timing belt. They’ve also “burped” it numerous times. Also, when I have the heater on and fan on high, the temperature gauge drops as I’m going down a mountain and not pressing the gas pedal. After driving, and I stop, it also slowly drops while idling for about 5 - 10 min.
When it’s warmer outside, I don’t have any problems, because I don’t have the heater on.
This has been going on for about 1 1/2 years now, and it’s starting to get cooler again, so I need to get it fixed or sell it. I just don’t have it in me to sell/trade it and pass this problem to someone else and they have to start all over with trying to solve the problem.