Kimura97

I have 1996 Honda Accord. Replaced ECT, temp sending, both fan switches and oem thermostat. Car run cool when driving, hot when idle and under load. The fans are working when jumped near the thermostat housing. Fan work when jumped with key off near upper hose. Fans work when the a/c is on. When car gets to temp the fans do not kick on when they should I believe (didn’t verify with with temp gun) Switch is good, I boiled it and checked the resistance. Today I blew my radiator because it over heated I believe. When I replace the radiator, is there any other parts I can replace while I’m at it. Don’t care about testing parts, I will just replace them. I’m at a total loss of what to do. I follow all the other forum post of trouble shooting. I read that there might be a radiator fan control module issue or a fan resistor? Can’t find it on a diagram. Thanks in advance

Kimura97

Also, do these fans have variable speed? Could be a bad resistor?

brakedrum

What brand fan switches did you put in it? I ask because there are some on the market that don't work right out-of-the-box. For those kind of switches, I always go to the Honda dealer parts counter and pay a little more.

If you had your key in position II, properly jumped wired the plug on thermoswitch and the fan runs, then the relay and fuses are good. If the fan does not come on under that setup, you might have a bad relay in the underhood fuse box. You can test the fan relay, and on some Hondas, there is another relay in the box that you can swap for a minute, to confirm a bad relay.

Kimura97

Replaced the radiator, ECT sensor, temp sending unit, fan switch A and B and thermostat, then bleeded the system...
so the fans are working properly, they are cycling with the a/c off. They cycle with a/c on. I did notice that they only cycle on for a short period of time, and every time is very consistent maybe 5-10 seconds. I’m thinking maybe they should be staying on longer? After I get of the free way, and drive it gets hot of course while in traffic, when sailing on the freeway, I issued at all

Kimura97

the fans are working properly cycling on and off with and without the a/c on. Car runs perfect on the free way, then gets hot while idling right off the freeway. Are these fans supposed to stay on for a longer period of time? They stay on for only a short period of time before they turn off, maybe just a few seconds

brakedrum

If your car is running "hot" or up in the critical zone on your dash gauge, then it sounds like the fan isn't running long enough or there is something else wrong. But if the temperature is just rising some, then that might be normal operation.

I THINK the primary switch is set to ground at about 190°F. and turns on the fan until it is happy with the temperature. A few seconds of operation when things are very hot does not sound right (20 or 30 seconds more normal), but if the thermoswitch is in spec, it is very precise in how it engages or disengages the fan, and might very well cycle on and off quickly around that temperature. A thermoswitch that is not precise enough will cause issues. The key question is whether your engine is getting dangerously hot before the fan comes on at all. If so, you might suspect the replacement switch, or maybe thermostat sticking in some way, but not as likely.

On my Accord, there is another switch that will ground the fan at 225°F block temerature, even with the engine off. It takes care of leftover heat would otherwise damage the aluminum block.

Kimura97

the fan are coming on at the correct temp at least according to the laser temp gun. Does the radiator fan control module regulate fan time? Or is it purely the switch?

brakedrum

The fans have a regulator that will protect the motors from burning up by shutting them off for a bit. Then the fan will come back on if the heat condition is still there. But that thermoswitch that sticks into the coolant flow is the main signal for the fan to come on, or keep coming on.

What kind of coolant mix do you have in the block? Is it fairly fresh?

Kimura97

i dont remember the exact brand but it’s the recommended and it’s brand new just did the radiator

brakedrum

If you had any air pockets in the cooling system, you would know because the engine would idle erratically.

Maybe just monitor the system and see what it does. If the dash needle stays up in the range in the photo you shared, then I would suggest that the thermoswitch is grounding the fan at far higher temperature than it's supposed to.

MAD_MIKE

Not always.

Kimura97 how did you bleed the cooling system?
Heater should be turned to full heat so the water valve is open.
Remove radiator cap.
Open the bleed valve on the backside of the thermostat.
Fill the radiator til a steady stream of coolant comes out, if you are like me and hate messes use a clear vinyl tube and fill the radiator while watching the tube for air bubbles.
The car must be on a level surface fore/aft and laterally.
When no more air bubble are present, give the radiator hose a good squeeze just to make sure nothing is stuck, close the bleeder.
Keep filling the radiator til it is up to the radiator caps level, gently squeeze the upper hose to make sure it has no air trapped in it, not necessary but I prefer not having to refill the reservoir after a test drive.
Make sure the hose to the reservoir is free of debris.
Verify the reservoir is clean and refill with fresh coolant.
The engine should NOT be running during bleeding.

Kimura97

I'm going to bleed the system again to make sure. I pretty sure I did everything correctly but it couldn't hurt to do it again. I bough this switch here. it is 10 degrees cooler and it seemed to do the trick. the car does fluctuate between 1/4 to 1/2 and gets no hotter then 1/2 on the temperature gauge now with this switch. it seems to fluctuate pretty dramatically between the two though, I am suspecting air in the system still? I want to thank everyone for helping me out, yall been great. ill keep you posted.

brakedrum

Depending on whether the car is in motion or sitting still, you'll see that needle move a lot. Don't know much about the switch you put in, but if it starts acting up, or doesn't last, you can get the factory ones pretty cheap through offers like this:

Honda fan switch

And I have to qualify that by saying that switch on eBay is NOT a Honda brand.