2000 Acura TL overheating at low speeds with A/C on

Is this a heater problem or an engine overheating problem?? If it is an engine overheating problem do you have white smoke out the exhaust which would indicate a head gasket leak into the combustion chamber. You could also have compression gases leaking intro the cooling system. Is the thermostat the correct one and if so is it installed correctly with the sensor/wax pellet part towards the engine and it there is a pilot/bleed hole is it facing up. You could also have an ignition timing problem or have a lean running engine and/or a plugged exhaust system

Water pump? Did you jump fan cooling switch (on thermostat housing) to see if fans come on?

did you change the thermostat? you may have to have the head gaskets tested.

Check for exhaust fumes in overflow bottle and radiator which would indicate a blown head gasket

Hello and welcome to FixYa! If you have overheating problem, it can lead to multipleissues. You may be running on low coolant that's why the vehicle overheats. Ifthat's the case, please add coolant and make sure that it sits on the rightlevel, too much coolant can cause overheating too for coolant will overflow. The vehicle may have a faulty or worn out radiator blowermotor that's why it overheats. If that's the case then you will need a blowermotor replacement to resolve the issue. If the radiator is clogged with dirt and rusts this issueoccurs too. The coolant doesn't flow normally on the cooling system if it'sclogged. If that's the case, I strongly suggest that you have the radiatorflushed to drain out dirt and rusts. If you think that the radiator served youenough then it's better to have it replaced. Please do check the radiator hoses, If you have worn outhoses it can cause coolant leakage which can result to overheating. A tiny holeis good enough for the vehicle to overheat. A faulty thermostat sensor can cause the issue too. If youhave worn out thermostat, the fan may not trigger that's why the fan won't workwhen under stressed conditions. A blown radiator blower fuse can cause thisissue too so I suggest that you check the radiator blower fuse and replace itwhen necessary. What causes the radiator blower fan fuse to blow? It's becauseof a failing radiator blower motor, If that's the case have the radiator blowerfan motor replaced. If the fluid in radiator doesn't circulate then it meansthat you have a blown head gasket or a faulty water pump. I suggest that you gofor the water pump replacement first specially if you think that it's near theend of it's service life. Usually, water pops out the radiator when engine isreved (a sign of faulty water pump and possible blown head gasket). Hope you find this information helpful enough and thank youfor using FixYa! Have a good one!

From your description of symtoms it sounds like you have a bad water pump. If the coolant is not circulating properly you will have a heating problem. Sometimes even a new thermostat can stick and cause the engine to overheat. I have seen them fail in as little as a week after they were installed.

I had the same problem, whole new radiator, new hoses, new thermostat, and still overheating. What the problem was for me...bad radiator cap...all that money and a $20 fix...try it?

Start with the easy one (hopefully). You probably have to replace your turn signal flasher. It's located behind the dash, driver side of steering column in the relay block (just pull out to remove).
Your overheating problem: Are you losing coolant, or is the car just running hot? Any leaks, puddles?
Check the cooling fans to make sure they are kicking on as the engine temp rises. If not, you may have a bad switch that is not telling the fan to go on. If fan(s) are operating ok, check the thermostat. If it isn't opening properly, it could be the cause of the overheating. If you have a leak in the system, then when it gets too low, it starts to overheat. Many possibilities, So, let me know the answers to the above so I can help further if needed.

If you can locate the temperature switch, looks like a large bolt head with 2 wires on it, bridge the wires on it, and this should make the fan work. If the fan works then this switch is faulty. If the fan doesn't then it could be the fuse, or a broken wire.
The fan switch is either on the radiator or on the thermostat housing.
If you can get to it easy, short across with a screwdriver.

you need to run the car and see if the fan comes on if it does change the thermostat and gasket if it does not you need a fan sensor