91 Accord overheating
 

Okay so this seems to be a common problem with these hondas, just need a little push in the right direction. Heres whats going on:

Car will overheat if sitting at idle, but when your on the move it seems to stay just below median. This will happen with no heat or A/C activated. The coolant in the overflow tank is at the MAX line. When the car does overheat, turning the heat on helps in a big way and almost immediately.

I figured the radiator fans werent working. I drove for about 10 minutes, checked and no fans on. Drove home and after sitting at idle for 30 seconds or so, the driver side fan kicked on finally. The passenger side fan remained off. Also, when starting the car and driving it for the first time of the day, it seemed to get up to temp much faster than before the overheating problem.

Any ideas? maybe just one fan is malfunctioning? It seems to me the passenger side fan is more centered over the radiator and should be the one used for cooling it, but thats just my reasoning. Please help!

Re: 91 Accord overheating
 

Update: Ive ruled out the cooling fan relay as a cause of the problem.

Also, any research ive done tells me the passenger side fan is the cooling fan and the drivers side fan is the condenser fan. So the cooling fan is not working properly. What can I do to troubleshoot the cooling fan?

Any suggestions are appreciated

Re: 91 Accord overheating
 

your going to need a digital multi meter to get further on this diagnosis. i simple test. get a paper clip or wire so you can jump a connection on the thermostat. and the one on the head under the distributor there both a two wire sensors. when you jump both and the fans turn on that means the wiring is good and your problem is either the sensors, fuses, or fan timer

Re: 91 Accord overheating
 

Update: Ive ruled out the cooling fan relay as a cause of the problem.

Also, any research ive done tells me the passenger side fan is the cooling fan and the drivers side fan is the condenser fan. So the cooling fan is not working properly. What can I do to troubleshoot the cooling fan?

Any suggestions are appreciated[/QUOTE]


GREEN= ECT(engine coolant temperature sensor) tells the ECU whats the temperature of the car for things like vtec or IACV sensors.........
YELLOW= gauge temp sensor....send the cluster a ground signal so the needle goes up or down......this sensor doesnt tell the ECU NOTHING!!
BLACK= radiator fan switch.....this is the one that triggers the relay so the RADIATOR(not the A/C FAN) will cut on

check these sensor....they are easy to locate and easy to replace...and all hondas have them so get them from a newer F22

Re: 91 Accord overheating
 

timing belt and water pump. when the car overheats at idle but cools back off when revv'd it means water pump has most likely gone bad.

Re: 91 Accord overheating
 

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Re: 91 Accord overheating
 

mine does the same thing but mine eats antifreeze

Re: 91 Accord overheating
 

To troubleshoot the cooling fan just use a paper clip and jump the connectors on the fan switch with the ignition on. If the fan doesnt come on then that sensor is bad.

Re: 91 Accord overheating
 

and i dont know about a 91 but my 96 has another fan switch that screws into the thermostat housing. The one on the thermostat housing controls the fan when the ignition is on and the one on the front of the motor is for when the car is off.

Re: 91 Accord overheating
 

1. Turn on the car with A/C, does A/C condenser fan (driver's side) and radiator fan (passenger side) both turn on? You already stated condenser fan works.

If radiator fan doesn't work, this may be due to a dead radiator fan motor or relay, etc. But, more than likely the motor. A good fan runs fast and strong, not weak.

2. If the radiator fan worked in above procedure, then turn off car. Now on the thermostat housing (lower radiator hose) is thermo-switch A, which turns the radiator fan on at around 194 degrees F when the car is running. Disconnect the green electrical connector from thermo-switch A. With a small paper clip or wire, jump the pins on the green connector. (use a small paper clip instead of a large one, you don't want to enlarge the electrical connections) Turn on the ignition, does the radiator fan run? If radiator fan runs, then it may be a faulty thermo-switch A. If the fan doesn't run in #1 procedure and #2 procedure, then it may be a bad radiator fan motor. You can also test the radiator fan motor directly, by unplug the radiator fan motor and applying 12 volt battery power directly to the motor side.

Note: The switch on the upper radiator hose housing is thermo-switch B, which turns the radiator fan on when the car is off, if the temperature is around 226 degrees F. (Do the test on thermo-switch A, located on the thermostat housing, lower radiator hose, not this one). The post with the picture with grey connector is thermo-switch B, not the one you will do the connector jump test on.

Re: 91 Accord overheating
 

Thanks for all the replies!

I thought I had fixed the problem, but I guess not.....

So.. New Update,

I havent taken the time to test the Radiator fan, but will do so here probably tomorrow. I still think it doesnt work but we shall see....

But there is a new symptom..... The car is going through coolant, like I have to fill it every 6-7 days. Im going to pressure test it in the next couple of days, but I took a good look and cant see any obvious leaking anywhere. My guess is that its a head gasket? Or would a non working fan cause fluid to burn up?

Water pump is an interesting theory, however with a full load of coolant the car runs just fine, no over heating whatsoever. Im guessing that rules out the water pump?

Thanks for all your help guys, I really appreciate it. If anyone out there has anymore tips, let me know.

Thanks

Re: 91 Accord overheating
 

A significant external coolant leak will be obvious. If no leaking externally is noticed then check your oil and make sure its a normal oil color. If it is a milky light brown then you have some problems. Check your exhaust for white smoke as well. Depending where on the head gasket is leaking (if there is a leak) it can drain into the oil or straight into a cylinder and burn up.

Re: 91 Accord overheating
 

Found a leaking hose in the system. Problem seems to be fixed for now. Hopefully it will stay that way.

Thanks everybody for your help. I have a new problem with the car, but I will start a new thread.

Thanks again!!!!

Re: 91 Accord overheating
 

Which hose was leaking?
Thanks.

Re: 91 Accord overheating
 

I had this problem before but it were just a radiator problem that couldn't hold the right amount of pressure it just pop during a diagnostic check-up.