'96 Rodeo 4 cyl - A/C cuts out related to water temp

A partially plugged or restricted radiator. If it is the original radiator I would think about replacing it if everything else checks out.

First thing to do is find out if it is really getting that hot or if you just have a temp sending unit that has gone out of spec. If it's cheap enough I usually just replace the sending unit and see if there is a change.

Next thought would be a clogged radiator. Any decent radiator shop should have a heat gun and be able to check the radiator for cold spots (indicates clogged radiator with no water flowing through that area). At 225k it's a pretty safe bet that you have some radiator issues.

Steve B.

Check for debris in the radiator and condenser fins. Check the fan clutch.

By flushed, do you mean it has had an acid flush or just a water flush?

I sort of recommend the acid flush... if the radiator or block is partially plugged, the acid flush will often open things up. The bad news is that if something is held together by corrosion, the acid flush will cause it to come apart and you will find all kinds of things leaking that you never had leaking before. But, I figure they are all things that probably need to be replaced anyway.

I agree that almost certainly you have a clogged radiator. The acid flush may open it up, and it may also make it leak like mad. If the latter happens, well, you needed to replace it anyway.

Oh yes, also make sure your engine timing is right on. Almost certainly this isn't the problem, but check it anyway.

--scott

The radiator has been flushed with an acid flush, also I have not been able to detect any cold spots in the radiator. The last water pump I put on, I did a test flow while the radiator was off, and volume output seemed more than adequate. I also washed out the fins of the radiator, but they really weren't that dirty.

I have thought about the fan clutch, although it seems to be "stiff" when cold and "free" when heated up

I will check the ignition timing to make sure, but I check it "by the book" each time I put a new timing belt on.

Thanks for all the input - sooner or later we'll get this resolved, at

I'm still thinking gunked-up radiator. If the radiator is partially clogged already the acid flush won't do it much good.

This is bad. It should be the other way around... the thing is supposed to become stiff when it gets hot in order to make the fan go faster when the engine is hot.

However, if the problem is happening at 70 mph, it probably isn't related to the fan. At highway speeds, plenty of air is going through the radiator so that you don't need the fan at all. In heavy traffic, the fan is critical.

Try this: take the thermostat out completely. If you do this, the engine should be running WAY abnormally cold. Does it?

--scott

I agree, especially at that mileage. Even if the tubes are clear the fins can get corroded and loose their ability to efficiently remove heat.

It should be stiff if the engine was very hot but it won't be very stiff at normal operating temperature. It will also be stiff when it is cold... that's why you hear the fan "roar" for a couple of seconds on cold start.