cooling fan sensor location ?

See below

Engine overheating as radiator fan doesn't come on. Condenser fan works.
Fuse good. Swapped relays no diff. Powered fan straight from battery and it works fine. Upper rad hose gets hot after engine warms up. Jumpered the cable that plugs into the temp sensor and when I turn on AC both fans run. Thus I think it is temp sensor but my friend says there is a switch on the rad and the engine and one is bad. I can't find any switch and have no manual. Am I right that it is temp sensor or is it a fan switch and if so can I test the switch and where is it? Accord EX 4 cyl. Thanks!

Check and test the coolant temperature sensor could also be the computer controlled of the fan relay

Apologies, this is a Honda Civic EX 4 cyl, not an Accord

cooling fan is not starting when engine gets up to temp. I replaced the water temp sensor with no results .( fans do start when A/C is turned on

Hi Bill Leach,

Unplug the fan switch located on the thermostat housing and use a jumper across the wire harness terminal and turn ignition switch ON. Does the fans comes on?

Yes the fan does start when I jump out the fan switch. I noticed bottom rad hose cool leading to the themostat. Is this telling me that it is stuck closed or not working at all. Top hose is hot as is rad iator

You have 3 possible causes for the condition which is due to insufficient or no coolant flow in system.

1. Bad thermostat. Stuck in closed position. This would be the most likely cause. Use a water to test the thermostat to see if it opens.

2. Faulty water pump.

3. Clogged radiator.

1992 honda accord work done:rebuilt head, complete headgasket set replaced(last week), thermostat, temp sensors, fan sensors(last month), timing belt & water pump(last year), upper/lower rad hoses, radiator(May). i started experiencing the temp rising to half way to almost 3/4 mark when stopped in traffic or sometimes red lights. fans are kicking on. took to shop during occurance and shop used temo gun and read max 205 degrees then fans kicked on when they are suppose to(gauge was 1/2 way). Other than thinking either temp sensor, thermostat or rad cap went bad or defective, could there be any other reasons for this? the shop stated usually when the cars overheat, the temp gauge usually goes bad and gives bad reading after that initial overheat. not sure if this is true or not. They state don't worry about it unless it goes to red. any suggestions?

This is an ez fix....if you can get to it

Http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_temperature-sender-switch-with-gauge-beck-arnley_18023506-p?searchterm=temperature+gauge+sender

Either your readings will change or they won't---it's an ez "peace of mind" item.......before you start to worry about nothing (we hope)....the gauge itself, i can't help with, i'd bank on the sender being damaged by the overheat 1st

If it remains the same.....you have a new preventative maintenance part now!

Could it be that you have an intermittent working relay for your cooling fans?....i have seen a car with some botched wiring...their fan was spinning backwards, the fins were inefficient in that direction.....it stayed relatively cool with the wind blowing into the radiator while driving


Let me know if you gotta buy something expensive--i may be able to aid you in getting it for less, than just walking in and purchasing it

The medic

this sender was replaced only last month. and the fans are running the correct direction witht the air flow towards block. Sender could possible be defect or bad. Will replace since still under warranty. Will let you know outcome.

If turning the A/C on and off makes the gauge moe, check the ground circuit connection. The gauge ground circuit is at driver side behind the headlights. Ensure engine to chassis grounding at engine mount of timing belt is good.

running the a/c does not change the reading on the gauge. i will check the grounds on the side wall just behind the headlightts and the valve cover and p/s bracket.

something different now happening. Temp gauge going lightly higher when in traffic and fans kicked on like normal then temp goes to normal. I decided to check the reservoir, it was filled to the top and had slightly overflowed so now i have too much coolant pressure in the system and forcing into it. The new hoses are tight as i canot sqeeze by hand. System had been bled andwith this problem, could this be another head gasket issue? Head had been rebuilt andsurfaced and now i wonder if the block surface is slightly warpped. any advise.. i have been pulling this head out a few times and it's becoming a pain.

When engine cools down, remove the radiator cap and cehck coolant. If you have air in system it is a leak with the head gasket but the head should not be the cause. Most likely the block surface is warped. The ridge between the cylinder 2 and 3 are usually ones causing the problem.

If the ridge around the cylinders are dark colored, which usually is the case, you need to reface the block. For minimal warpage I usually use a grinding stone to level the surface, which works but you must know what you are doing before attempting this. You have to be careful when sealing up holes that can allow grinding residue from getting to the lubrication system.

That does make sense because everytime i removed the head. 2&3 portion of the gasket were always failing even after the head resurfaced. This does help alot. I will consider having shop surface so i can assure the entire surface is even. Thanks for your guidence.

You are welcome.

Btw when too much is taken off the head and block surfaces, you have other complications. The compression would increase but the valve timing would be retarded and the distributor has to be turned further forward to advance the ignition timing, failing which you would have poor performance issues.

The timing belt can be off up to 1/2 a tooth which you can't compensate except with adjustable cam pulley or an offset key which you cannot buy anywhere. I normally fabricate them myself.

Yea, i am getting nervouse about that because now my valve clearance will be more limited than before. Too bad there are no spacers to make up this difference, unless the performance Headgaskets are more thicker than the Std. Felpro MLS to make up that loss. hhmmmm.

Valve clearances are not the problem as there would be sufficient clearance between valve and piston. Just make sure the indents on the valves are cleared of carbon build-up.

Not sure if performance gaskets are thicker but you can always ask around. Let me know so that I have another option when required. Over here we don't have much info on performance parts.

Question, since i will be taking in the block to get surfaced and steam cleaned, they suggested i take in gutted but don't have to. Since i will have everything taken apart, i am considering replacing the piston rings, main bearings, pan gasket and possible oil pump as well even though there were no issues with that. Am i just wasting $ or best to do it since block is bare?

Check through all the components first. A well serviced engine would not have much problem with the manin bearings but the con rod bearings might need some attention. Forget about replacing the oil pump. I have yet to see any fail. Pistons ring replacement would be a good idea as the oil rings would most probably be worn or sludged badly.

The pan gasket would most probably be hardened by now so should be replaced. You might have difficulty getting the gasket off the pan. Use some heat from bottom of oil pan onto where the gasket seats and you would have no problem peeling it off.

The balancer gear O-ring and oil seal should be replaced since you are there.

I have everything to do the teardown and will be ready this weekend or next. Engine was taken well care of and when pulled head out before no sludge what so ever even before that rebuild. Question though, i havde been noticing when car would start to overheat, i would kick on the a/c fort eh fans and the car would cool down quickly. I would think it would have been the opposite due to the extra power it would need to run the a/c. Still notice coolant escaping from looks like the rad cap even though replaced twice. Water is traveling so it should not be the water pump even though it's only a year old, but could be faulty but not leaking through weap holes. all hoses replaced. Heck almost everything is new, exept the block. Hopefully this block rebuild will work out.

When A/C is not running, the fans would kick in only when the fan switch is trigggerred. When A/c is turned on, the fans are running continously as long as the compressor is running. That would keep the temperature lower.

Where is coolant escaping from radiator cap?

Yes, seems like the base of the cap because there are splash marks on that area, cleaned are to make sure not mistaken but same area. radiator is also about a year old and no cracks or damage. Maybee too much pressure in system because hoses are very tight after ong drive and while running, cannot squeeze hoses much at all. system was bled multiple times. My guess cylnder pressure. IDK. i fugured block surface has slight warp which is why i'm resurfacing.

Check the radiator cap seals and seat on radiator. Any damage or uneveness can result in leaks there. Even if the system is pressurrised, the released pressure should be going to revcovery tank and not through radiator cap.