98 Honda prelude overheats when at a spotlight or stop and go traffic. I replaced the thermostat and worked ok for awhile,then.the problem came up again...I noticed if I turned on the heater,the temp.drops,and.coolant level was good and fans kicked on. Also when I turn on the heater,it blows out cold air for awhile,and then the temp goes down when the heat finally comes out.also when I rev the motor, it drops the temperature also.

Possible thermostat faulty, Thermostat automatic, stays shut, till water reaches correct temp, if it goes faulty, (ie) does not open after reaching running temp, water will not circulate, so engine overheats

Verify fan operation(be carefull not to let the car overheat) and if they dont work try these steps. (If you have electeical know how)
check all fuses
check relays by swapping with another known good relay.
look around with a tester and see where along the circuit you are getting voltage.
replace the
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is the cooling fan working with and without the a/c on.this could be the problem and is it spinning fast enough.if its starting to seize up it won`t be turning at a fast speed like it should.with the a/c on it puts a load on the motor that causes it to work harder thus run hotter.another thing to check is the rad flow as if its not flowing enough coolant it can cause this as well.have you changed the thermostat as if its not working properly it could be not opening as it should again causing the motor to run hotter.

make sure you cooling fan is coming on (this should when the temp guage starts to climb) and also make sure the temp sensor that turns it on/off is good. You could also have low coolant or bad thermostat (the wrong mix of coolant) or oher major mechanical issues but start with the fan and coolant level/mix

Definitely change the transmission oil - could be some rubbish in there stopping the actuators working correctly. If that doesn't work, could be time for rebuild with new friction material in the clutches.

Sounds like a crank postion sensor. Is this only when the car is hot/reached operating temperature

Yes with airflow it work (on the interstate) but with no airflow to get rid of the A/C heat causes engine to overheat. Let's look at two possible things...first the A/C condenser fan by the radiator & then the A/C water temp switch.

IN ORDER:
Check the 30amp CDS FAN fuse (replace if blown) if it is OK then replace the the Fan#3 RELAY (which turns on the A/C condenser fan)...Then if needed replace Fan#2 RELAY (which can also control the A/C fan speed).

The Fan#2 relay can wear out and cause the type of problem your having

Is it an hour idling? If you are overheating going down the road, this is either a thermostat, or a plugged radiator. The fan will contribute to overheating sitting still.

Hi, are you sure u need a new thermostat? Running in the mid temp range is ok. If u think u need to change it, here's the info. I believe your Prelude uses a 195 degree thermostat, but go to a good parts store and give them the year make, and model and ask them what thermo. u need. Also get a gasket. The thermostat is located at the end of the radiator hose (the top hose). Disconnect the house at the 'housing' and remove the housing (2 bolts), the thermostat is now exposed. Pop it out (u might need to persuade it w/ a screwdriver (gently pry it out) and remove the gasket, clean gasket surface. Install gasket and thermostat, being careful that they stay in position when u bolt the housing back in place. Re-attach radiator hose, top off coolant, (50/50 Mix), and last, there is a bleeder valve which I believe is on the housing that u loosen after starting the car, when air stops coming out, tighten and u r good to go. Do u have any idea when the coolant was last changed? U might want to consider it if it's been a long time, or u r not sure. Let me know how u make out, or if u have any questions. Good luck! countrycurt0

A clogged radiator or thermostat will produce the same results.Replace both.