High Temperature at Stop and Go Traffic

1990 Honda Accord, 4Dr, LX, AT, 191K. Please see my other posting subject "1990 Honda Accord Engine RPM Racing" for more detail description. What happens are engine heater hose leaking coolant, continue drive which may cause engine overheat. Fixed engine heater hose, but now engine temperature jumps to high at stop and go traffic. Temperature back to normal while driving. Radiator and condensor fan don't seem turning. Anyone knows how I can check the exactly problem my car had?

 

First, run your A/C with the engine running. If the cooling fan comes on then you might have a bad coolant sensor. (Running the A/C bypasses the coolant sensor.) If the cooling fan does not come on then you might have a bad fan fuse, relay or fan motor. You can narrow that down by checking the fuse in the black box under the hood, on the passenger side of the firewall. It'll have diagrams of the fuses and relays within on top of the box. If the fuse is bad you can replace it but it might mean one of the following is bad. You can test the cooling fan relay by switching it with the relay for your power windows. They are the same relay. Then let your car warm up with the A/C off and see if the fan kicks on....or you can test your power windows too. If they don't work then you know the relay you took from the fan circuit and put in your window circuit is bad. If nothing changes by doing this then you can suspect the fan motor. Check your plug connections to the fan motor. If all is good then you probably have a bad motor. They are not hard to replace with a decent metric tool set. Make sure you put a little dialectric gel (you can get a single use packet for cheap from any auto parts store) in the connector plug though to help prevent corrosion.

Happy hunting and lets us know what you find out.

 

Thanks oneprblmcat! When I test by turning A/C on, does it mean put the dial to as cold as it can?

 

By the way, where is coolant sensor and how can I bypass it? If you can give me the manufacture part #, I will be able to find it from dealer's web site. Thanks!

 

Yes, have the A/C on high. Though I think it should work either way as long as the A/C button is switched on.

I believe the coolant sensor for the fans is at the thermostat housing, where the upper radiator hose goes to the cylinder head. As you are looking at the cylinder head the thermostat housing will be on your left (pass. side) below the rubber air intake hose. I think the sensor will be sticking out horizontally towards the front of the vehicle. As for the number, I do not have that. But any autoparts store can get you one if that is your problem. Just remember there are two coolant sensors. One is a temperature sender that sends a signal to your ECM so your gauge will tell you the engine temp. The other one, the one that activates the fans, is usually just a switch that activates at a certain temp. So it may be refered to as a "coolant temp. switch" or something similar. Usually it provides a ground when active. This ground is to trip the little magnet in the relay which completes the connection to give power to your cooling fan. If it is a two prong connection at the sensor then you could theoretically jumper the connections to activate your cooling fans. If it's a single prong connection then you would simply have to ground the connector to the engine. But then the fans would be running all the time. I wouldn't recommend doing this as your engine would have a hard time achieving proper operating temperature. Plus it's kind of mickey mouse in my book. I prefer to solve it properly so you'll have no worries later.

Good luck.

 

Checked fuse and look good. Switch cooling fan relay, window still work. Unplug radiator fan switch and short connector, hear relays are clicking (one is cooling fan relay and another one in driver's side front corner. According to Haynes repair manual, it is possible a condenser fan relay.), but both fans didn't turn (are they suppose to turn after shorting?). Unplug condenser fan switch and short connector, didn't hear relay clicking and no fans are turnning. I will find a wire and unplug fan electrical connector to connect directly from fan motor to battery to see whether fan is turnning or not. If it is not turnning, motors are bad (wondering both are bad at the same time?). If it is turnning, sensor switch is bad. Am I right?

 

Both fan motors are bad. Bought two new fan assembly and installed them. Now, whenever I turn on A/C both fans are turning. After driving and heat up engine (engine temperature gauge still in normal range) with A/C off, none of fans are turning. Does this mean sensor is bad? Should I wait until temperature gauge goes to high then check fan?

 

The fans will automatically turn on when AC is selected.

With AC off, the fans will only turn on if temperature exceeds a certain degree.

Your fans are operating as they should.

 

Thanks for the replied! Since temperature gauge is still in normal range, I will keep my eyes on it and check fans whenever it is abnormal. Worse things won't come along. I just had ignition electrical switch (also accidiently blowed IG fuse when repairing), heater hose by pass (caused engine overheat possiblly, engine noise before warm up) and both fan motors fixed in the past 30 days. Now, my alternator isn't working as you can see from my another posting. I will have to fix alternator this weekend. Can't affort a new car at this time!

 

Just opened my old radiator and compressor fan motors. Both motors' brushes worn out.