dchamberlain

I have a '91 Accord Wagon. I came out this morning, about an hour after making a short trip, to find the passenger side cooling fan running.

This fan has run before with the key off, usually for 1 to 10 minutes after turning off the key, whether the engine was warm or not. But now it's just running. The car is stone cold and it's 39 degree's out.

So I started searching here and found out stuff about temperature sensors and the fan delay timer and stuff. I disconnected the temp sensor where the upper radiator hose hits the block, no change. I disconnected what I think from diagrams is a temp sensor in the head under the distributor. I broke, and then disconnected another sensor, which appears from a diagram to also be a temp sensor, from behind the one described above. All no change, fan still runs.

I swapped the fan relay in the fuse box in the engine with a different one. Still runs. If I remove the fan fuse, or the fan relay, it stops. Otherwise it still runs.

So if I am understanding this correctly I need a fan timer.

First question is, am I diagnosing this correctly? Am I missing anything?

Second question was going to be what is the part number for a fan timer, cause I couldn't find it. But I did a google search and came up with 37740-PT3-A01. Does this sound right?

Thanks,
David Chamberlain

redbull-1

Here's a link regarding the fan timer. The part number appears correct.

http://techauto.awardspace.com/overheating.html

dchamberlain

Anyone else have any insight as to whether I'm diagnosing this thing correctly? I'm about to park it front of the house with a For Sale sign and call it good.

adrbi

Most likely you have a failed temp switch, start by replacing the switch on the housing with the hose coming from the top of the radiator first. It's a lot cheaper than replacing the fan timer module. I had the exact same problem and the switch fixed it. Cooling fan operation is controlled by the fan timer module, which monitors signals from a thermo sensor, underhood temperature sensor and the A/C compressor clutch. The timer operates the cooling fan by controlling voltage applied to the fan relay control coil. Battery voltage is applied directly from the main fuse to the relay switch circuit and timer bypass circuit, and voltage is applied to the timer main circuits through the ignition switch start and run contacts. The timer module controls voltage applied to the relay control coil circuit, and the control coil circuit is completed to ground either through the thermo sensor or timing module. When current flows through the relay coil circuit, the relay contacts close and voltage is applied to the cooling fan motor.

During normal operation, voltage is applied to the relay coil by the timer module and fan operation is controlled by the thermo sensor. When coolant temperature is approximately 190°F, current flows through the relay coil circuit and voltage is applied to the fan motor. When coolant temperature is below 190°F, the thermo sensor contacts are open and the cooling fan does not operate. However, when the A/C is turned on, the timer energizes the relay coil and the cooling fan operates as long as the clutch remains energized.

When the engine is turned off, the timer module remains energized and monitors signals from the underhood temperature sensor. If underhood temperature exceeds 220°F, the timer activates the fan relay and the cooling fan is energized. The cooling fan will operate for a maximum of 15 minutes after the engine has stopped or until underhood temperature drops below 220°F.

Let me know if this helps.

ericanical

Having the same problem on a 91 Accord LX. The switch that sits in the upper radiator hose to block housing is a coolant temperature sensor 37773PT3A01 on this vehicle. Is this the correct sensor to replace? There is a temperature radiator fan switch 37773PT0004 that sits behind the thermostat housing. It's operation was checked by placing it in boiling water and it had continuity when the water reached boiling point and no continuity when it cooled down. What should I do next? Where is this underhood temperature sensor located? There's an air temp sensor 37880P05A00 that sits on the intake manifold. Is this the underhood temp sensor?

eldog80

If you are talking about the radiator fan, then I would check the cooling fan relay. My 2000 Accord ex 4cyl had a similar issue. My radiator fan on the passenger side would run for a while after my car was parked and shut off completely. When I took out the relay(s), there are two, and shook them, I would hear a piece rattle around. I just replaced the one that was bad and a year later still no problem. Easy fix.

holmesnmanny

I'm just going to quote that again since nobody appears to be able to see his post.

erichandymanaut

This fan timer bypass repair fixed my 1991 Honda Accord LX. Wire colors were the same and I used a solderless quick tap splice connector to connect the wht/grn and blu wires.
http://hondaswap.com/threads/bypassi...nction.526022/