very intermittent overheat on 98 Maxima

[Tom7227]

This is going to be a long shot but I appreciate any help anyone can offer. Sons 98 Maxima with 240K on it has an intermittent overheat. We drove for several hours on Sunday and it popped up after about 2 hours of City driving, but went back down as soon as he put on the heat and stayed down.

I don't think it's the water pump or the thermostat because I expect both would cause consistent and fairly quick problems. I am thinking that it may be a failure of the cooling fan(s) to turn on when the unit gets stressed. We haven't even popped the hood yet (in New York City) and so I don't even know if there is one or two cooling fans. I assume one and I assume it has two settings and that there's a failure on what I will call the high speed setting.

Anyone have any thoughts? Suggestions on how to test for these things? I'm handicapped given the location - would much rather deal with it in White Bear Lake - but he and the car are in NYC and I'm out here for a visit.

Thanks for your help.

Tom

[Macgyver55]

Most cars will run the electric fans anytime the a/c is on. You could do a quick check of the fan operation by running the car with the air on to see if they work. If they do work, try driving with the a/c on and see if the temp stays down. If so, the temp switch for the fan may be the problem.

If the fans dont come on at all, check fan fuses and relays before looking at the temp switch.

[Tom7227]

Checked it last night and found that there are two fans and both kicked on when the AC was turned on. Drove for 45 minutes in traffic with no problems. Can a thermostat cause an intermittent problem and cause an overheat in the middle of a trip and then be OK again?

[Jeremy airjer W]

Check the front of the radiator (in between the radiator and the condenser) for debris build-up. It is one of the most common problems I see as warmer spring weather starts appearing. Sand, pollen, and the fluffy stuff that floats around in the spring like to accumulate on the front of the radiator. I have a blow gun setup just for blowing out radiators that this happens to. You would be surprised at the sandbox quantity of debris a radiator can hold!