HELP! Having an issue with my coolant system on my 05 maxima se. The other morning car heat was blowing cold every time I came to a stop light but once I was on the gas again it heated back up so I assumed it was the thermostat or air in the coolant system. I burped the system and it seemed to fix the heat issues but i also noticed the other day that my reservoir was low so I filled it back up. Well I checked it today and it's almost bone dry. Car isn't overheating at all. Also upper radiator hose seems to have a lot of pressure on it once car is warm and especially once it's hot. Lower warms up after car is at operating temp somewhat whether the thermostat is working or it's just heat from the block I'm unsure of. Seems as if when the antifreeze expands it's not going back into the reservoir but Im assuming it's going back into the radiator when I'm driving. Need help cuz I'm clueless to what it could be smh.