If your 1999 Toyota Tacoma is still overheating when the AC is on, it could be due to a few issues. One possibility is that the cooling system is not functioning efficiently, which may include a failing radiator, clogged coolant passages, or a malfunctioning water pump. Another potential cause could be insufficient coolant levels or a leak in the system. Additionally, the increased load from the AC could be straining an already weak cooling system, so it’s important to check these components thoroughly.
Blown head gastet, radiator leaking, thermostat needs to be replaced Blown head gastet, radiator leaking, thermostat needs to be replaced
You should check your Toyota Tacoma's owners manual. There should be a diagram for the location of your thermostat.
Try replacing the thermostat.
The thermostat is located behind the timing belt above the alternator when you look for it you will see a round shape above the alternator and you take off the two bolts on the cover that is round and your thermostat will be there
It might the thermostat stuck close or the water pump does not work and has to replaced.
http://www.ehow.com/how_4590731_change-thermostat-toyota-tacoma.html
yes, interior changes happen post 2000.
The 1995 Toyota Tacoma thermostat housing torque specification is 40 pounds. The amount of torque on the thermostat housing bolts is not that important. You basically do not want to break the thermostat housing bolts.
Buy a thermostat and install it.
when it slips or grinds
If it's just occasionally, it may be a sticky thermostat.
I have good news for you. All 2001 Toyota Tacoma 4 cylinder engines cam are driven by a Timing Chain and no replacement is necessary. The Toyota Tacoma V6 has a Timing Belt that must be replaced every 100,000 miles. It is an interference engine so it is critical that it be replaced on time.