I've been having this problem for a while now. After turning the car off, the upper hose is hot, but the lower pretty cool. Both fans come on when the A/C is running, but neither runs when the A/C is off. The fan nearest the battery comes on after the car is turned off. Any help anyone can offer is appreciated.

 

It can be a plugged radiator, & possibly a sticking thermostat. With a plugged radiator, it flows so slowly the coolant has plenty of time to cool down, but the flow is too small to provide proper cooling to the engine.

Chemical flushing of the radiator to remove scale & crud, or a new radiator depending on how it looks.

 

Good Call Jim..
I'd go with the Flushing 1st New Member...then if the radiator is not good, then replace it..

WheelBrokerAng

 

Will put your advice to work and get back with the results. Thanks!

 

To add my two cents and not loose what Jim posted. Most of the time the best "flush" is gained by removing the t-stat and doing the procedure.....so why not throw in a new t-stat....as he suggested.

Last, be sure to properly bleed the cooling system upon refilling with coolant. A new rad cap never hurts or have the current one tested.

 

Come to think of it, my cap is looking pretty rough, so replacing likely wouldn't be a bad idea.

I have read what I consider to be conflicting instructions as to where exactly the t-stat is located. Haynes manual advises in the housing where the upper hose enters (or exits?) the engine, while others state it is the housing where the lower hose enters/exits the engine. I guess the answer lies in knowing exactly what the directional flow of the whole cooling system is, but as you can tell, I haven't been able to nail that down.

 

4th, 5th and 6th gen 4 cyl (90 thru ~02- too lazy to look up 7th gens) the t-stat is where the LOWER hose connects....pass side between the valve cover and the firewall.

3rd gens are different

 

1990(?) thru 2002 (F-series engine)

Beginning in 2003 the K-series engine has a thermostat up front between the block & the radiator.

For your 1993 you follow the LOWER radiator hose back over the transmission towards the firewall. The thermostat housing is kinda below the throttle body. I've seen A LOT of books make the mistake of saying it's in the upper hose.

 

It's probably the thermostat (I just changed mine in my 1994 ... only 90K miles). Same thing ... upper hose hot and car over heats. Lower hose cold. Haynes manual worked for me.

First, while the system is still pressurized and trying to over-heat, look for hairline cracks in the top plastic section. Actually, look for any leaks anywhere (hoses, over-flow bottle, radiator cap, etc.). Change radiator cap if it's old.

Go ahead and flush the radiator. If it's the original one, be very careful with it. If water goes in the top and out the bottom good, it's not clogged up.

If the thermostat is bad, its probably stuck closed. The water can't circulate. Also, the hot water can't get to ECT-A fan switch, so the fans never come on by themselves. You can check thermostats suspended in hot boiling water. I made a little plug for my ohm meter and you can also check ECT-A by suspending in boiling water.

You can't boil check ECT-B (near upperhose) because it doesnt open until 220f and I could never get water hot enough in pot. However, it sounds like your ECT-B is working if fan runs after car is turned off. Your ECT-A is probably ok also.

 

Yes, it was hard to find and I'm not sure why they didn't explain it in the Haynes manual (but they often assume knowledge of cars).

94 Honda Accord uses a gravity fed system:

Radiator (to)
Lower hose
Thermostat
Water Pump
Engine
Heater Core
Upper Hose (back to)
Radiator