I've recently encountered a problem with my 97 accord dx. After generating enough heat, if the car is allowed to idle for more than a few moments, the heat gauge starts climbing towards the red area.

I've noticed, during this time, that the cooling fan on the passengers side of the hood never comes on. However, if I turn the car off the fan will immediately come on. So far, I've replaced the thermostat, and thermoswitch A. replacing the thermoswitch seems to have had no effect on the fan. I have confirmed that the fan is functioning properly by removing the connector and shorting the pins. When I do this, the fan turns on and spins.

Also, I've noticed that, if I rev the engine with the car in park or neutral, the temperature gauge on the dash will quickly fall off to a safer level. How would revving the engine aid in lower my temps despite the cooling fan remaining off?

I've determined that the thermoswitch is functioning properly - does anyone have any other ideas as to why the cooling fan would not be coming on while the car idles? Could it be my fan control module?

 

Did you replace thermoswitch A near the thermostat housing? There is thermoswitch B near the upper radiator hose fitting, engine side which some have mistakenly replaced.

If you replaced thermoswitch A correctly, check wiring by shorting thermoswitch A connector, and turning keyswitch to On. Both fans should come on. If not, remove the connector for the non-functioning fan and check for 12V. If you don't have 12V, there is likely a wiring fault or fan relay fault for that fan circuit.

good luck

 

Thanks for your reply. Yes, I replaced thermoswitch A (near the thermostat housing) yesterday and the fans still do not come on when the gauge begins to rise while idling. I've removed the fan from the connector and confirmed that the fan will run when I short the connector.

The only odd thing that I can think of is that the OEM thermoswitch that I bought seems to have a longer plastic piece than the original Honda part had. I do hear a "click" sound like it is clicking onto the connector, but it does not fit the same as the original part. This, in turn, does not allow the the plug to fit snugly on the connector. By this, I mean there is a small gap. I'm assuming that it was intended to fit like this and that there is contact being made. Has anyone ever run into something like this? Regardless, I really doubt the replacement thermoswitch is faulty.

Is it possible that an incorrect temperature is being reported to the temperature gauge? I find it strange that it can read overheating, basically all the way to the red area, and then when I rev the engine the needle quickly falls back into the 3/8 range. Initially I thought this was a result of the outside air being forced over the engine as the car is moving, but the same thing occurs while the car is simply idle in the driveway. If I hit the accelerator with the car in park or neutral, the temperature will fall. Aside from the gauge, I've seen no other symptoms of the car overheating.

I'm planning on getting an actual reading of the temperature with an infrared gun while the gauge starts to climb to confirm that the car is actually overheating. I suppose if the gun confirms that the temperature is above the fan on threshold temp that the issue is probably related to something electrical?

 

I think a weak water pump would do that .. As I understand how they work, there is an impeller in there and sometimes it can be damaged .. that would explain why it works at higher engine rpm?

 

Right, but if the problem is my water pump, shouldn't the fan still be kicking on once the car heats to > 199F? I've seen no fan activity since noticing this problem a couple of weeks ago. The fan only kicks on if I turn the AC on or shut the car off.

 

If both fans turned on when you shorted thermoswitch A, then all of the wiring for the fans is correct. The problem has to be with the thermoswitch A or maybe some bent pins in the electrical connector?

If you go the part from Honda, post the actual part number just to make sure you go the proper sensor.

 

Unfortunately I did not get the part directly from Honda.

This is what I installed:
Duralast/Cooling Fan Switch - Radiator (TU197) | 1997 Honda Accord 4 Cylinders 2.2L MFI | AutoZone.com

Like I said, the electrical connector plugs into this without any issues and I do hear a clicking sound indicating that its secure. However, the length of the plastic on the switch is longer than the original Honda part. I'm wondering if its possible that no contact is being made because of this. Would you recommend getting a Honda thermoswitch in this situation?

I'll take a look at the pins and check them out when I get a chance.

 

I just got back from work and really can't see a whole lot out there currently but something that kind of seemed a bit strange to me is the lack of slack in the wiring at thermoswitch A. I've attached an image that I quickly took kind of showing this. Is it possible that the lack of any extra length in the wire could be causing a short? Does this appear normal to anyone?

 

If shorting the connector causes the fans to come on, the wiring is OK. Have you checked for air in the cooling system (open bleeder on cold engine and run till coolant emerges)? Low coolant level can cause apparent overheating quickly which might respond to throttle.

good luck

 

Can you tell us the two wire colors going to that electrical connector for thermoswitch A?