I have Honda Accord '95, 4 cylinders V tech engine. when I drive in freeway or regular road for a while, my engine temperature gauge is below midpoint which indicates it is running fine. But when I drive stop and go or idling (especially in traffic bumper to bumper) my engine temperature gauge goes up above midpoint sometimes almost to the red end. When I see this, I immediately turn on AC and this brings down my temperature gauge below midpoint slowly.

It seems that my radiator fan does not get turned on when the engine get really hot. But my AC on makes both fans go on. But sometimes when I stopped my car at the parking lot, I can hear the radiator fan go on. So I checked one time under the hood and saw radiator fan on. So it seems that radiator fan works only when engine is stopped.
Why is this radiator fan not go on when my engine was really hot almost to red zone while I was driving bumper to bumper or idling?

Do you think I have a fan switch A or B problem or ECT sensor problem? I am a little confused from other posts on this issue that ECT sensor and fan switch is same thing? do you think I could have problem with my air locked in the coolant system? What tests should I be performing for my radiator fan problem?

 

Don't post problems in greeting area. Add your car details to your signature line.

Theremoswitch A (near thermostat housing) fault is likely. Remove connector and jump connector terminals, turn keyswitch to On, and both fans should run. If no fans when engine is hot, then thermoswitch should be replaced.

good luck

 

My apology for posting in the wrong location. I thought posting in "general help area" was the correct thing to do. You said that I should Add my car details to my signature line.Where is that? I am a bit confused.

Anyway thanks a lot for your help. I tested my thermoswitch A with jump connector and both fans got turned on immediately.

1) Before I replace this switch A, should I do also relay and fuses test (jump to battery) to confirm my bad switch A or this test applies only for bad fan motor?

2) If yes, how do I do this test or check voltage and resistance with test meter?

3) How do I test my ECT sensor?

4) Where is the best deal to buy thermoswitch A for my car? Do they normally test it before they sell it?

 

This test is definitve for faulty thermoswitch A, if you're sure the fans were not coming on in slow/idling conditions where overheating was seen.

Fuses and relays are ruled out by the jumper test.

However, if you're unsure whether the fans were coming on or not, you could perform a test of temp switch A. Suspend in pan and raise temperature of water. Switch should close w/ heating (VOM leads w/ resistance check to allow closure to be seen). Switch should close about 199F, just before boiling condition or measure w/ candy themometer or IR thermometer.

good luck

 

To test further, you mean I should remove the thermo switch A and put it in a pan of water and heat it to a boiling temp, right? Just curious that how does switch close? can we see the the two pins contacts close up together? And how do we test resistance with VOM meter?

Can I replace thermo switch A with switch B (swap switches from one location to other) and will it work just for a test again? meanwhile I order online.

Thank you.

 

No, you can't see the switch contacts. You measure resistance across the switch connector pins w/ a VOM measuring resistance. If you've never done this type of check, I suggest you replace thermoswitch A.

You can't swap thermoswitch B as it has a higher switch temperture of 225F.

good luck

 

Thanks for help! I was trying to buy thermoswitch A or raditor fan switch A online Auto Parts Warehouse | Car Parts & Accessories, Truck Parts, Discount Auto Body Parts Online. about $40. It does not tell you whether it is switich A or B. It gives description of 225F which sounds like switch B according to your description earlier reply.

Can I drive without thermoswitch B until I get to Autozonme store ( 2 miles)? Or will that be harmful for my engine?

can the store manager tell difference between switch A and B if does not mention on their parts description? i guess I have to tell them whether I want radiator fan switch or condensor fan switch, right?

 

You need thermoswitch A (199F switch temp), not B (225F). Not sure I understand what you're attempting.

good luck

 

At Autozone store where I can buy this part Thermoswitch A, doesn't have description switch A or B in their inventory computer, (but says radiator fan switch). They told me to bring my old parts so that they can match with their parts to confirm it is switch A not B. So I am planning to remove the thermoswitch A from my car and drive this same car to get to the Autozone store. That should not be a problem for 2 mile drive, right?

 

The dealership sells the switch for $52. The part number is 37760-p00-003 or 37760-p00-004. You may be able to buy one from an online store for cheaper, but they charge shipping. I have found Honda parts on ebay for reasonable prices too.

As a temporary fix, you can short that connector while driving. Overheating the car can cause premature head gasket failure which costs way more than a temperature switch.