1997 Honda Accord Logo
Posted on Nov 25, 2008
Answered by a Fixya Expert

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Cooling fans dont operate when engine is on

Engine overheating because cooling fan not operating

  • Anonymous Dec 03, 2008

    fan is not on while the engine is over heating

  • pmackins Dec 04, 2008

    Suddenly yesterday I noticed my 97 Odyssey was overheating to the point of the redline. The engine fan only came on when I turned on the A/C but only for a limited time. The engine fan ran after the car was turned off. I checked the radiator when the car was cold and the coolant did not appear to be circulating.

    Where exactly is the temperature sensor located and how can I change it?

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  • Posted on Nov 25, 2008
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Faulty temperature sensor. It's near where the thermostat lives in the motor. In an emergency you can wire the + side of the fan to the accessory panel, just know that the fan will run the entire time the car is on.

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Experience overheating. Cooling fan is not working unless A/C is on. Unable to locate any leaks on hoses or radiator. Coolant is draining thru reservior.

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FANS WONT COME ON ,,ALL FUSES,RELAYS AND ELECTRIC FAN MOTORS ARE NEW,,THERMOSTAT IS GOOD,,WHERE IS ELECTRIC FAN TEMP SENSOR LOCATION

op
why not post symptoms first and not a barrage of parts.
must we decode that to a symptom,. kinda hard right.

I will not guess. what is wrong, nor what is not working on your car. now what fans you are talking about, up to 4 fans on cars.

cab blower fan (wild guess blower is ok) and so is HVAC, ?
radiator fans
Condenser fan.

my wild guess to , engine over heats?????????
if yes, the scan it first. no not last FIRST.
it dont work like you think its not a 1988 Samurai.
sorry,
on modern cars, they got smarter, the engine goes
gee the PCM knows water temp why have a fan temp regulator.
hark , now it dont. (saves cash on useless parts)
but has a relay , (well until you have my car and the relay is now 100% electronic, called a huge transistor)
we've used this tech in industry for years, but car makers just learning how still.
i digress. but evolution and history helps diagnosis.
what is there?

Ill look for you, ive posted this 100s of times
the book is 4 bucks to see online. the real deal
lets look now.
XL-7 (the dash matters big time)
answering for , overheats engine, and fans on RAD dead.
(some are staged, PCM brains... now. and also chain ops based on if A/C is on or not) facts.
first I see 2 fans... ok.
the next page shows nice block diagram of the fan system
yup, NOT Simple.

ill post those words for you.
"The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the engine control module (ECM) to operate both fans together at low or high speeds. The cooling fans receive positive voltage from the cooling fan relays which receive battery positive voltage from the underhood fuse block.
During low speed operation, the ECM supplies the ground path for the low speed cooling fan relay which is fan 1 relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the fan 1 fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the series/parallel relay which is fan 2 relay, and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. The ECM grounds the high speed fan relay, which is fan 3 relay, and the series/parallel relay, which is fan 2 relay through the high speed cooling fan relay control circuit. This energizes the series/parallel relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and provides battery positive voltage from the fan 2 fuse 1 on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.
When the request for fan activation is withdrawn, the fan may not turn OFF until the ignition switch is moved to the OFF position or the vehicle speed exceeds approximately 16 km/h (10 mph). This is to prevent a fan from cycling ON and OFF excessively at idle.
end quote.

i bet you didnt scan it , like 99.9 % of all posters here dont.
DTC Descriptors
DTC P0480: Cooling Fan Relay 1 Control Circuit
DTC P0481: Cooling Fan Relay 2 Control Circuit
DTC P0691: Cooling Fan Relay 1 Control Circuit Low Voltage
DTC P0692: Cooling Fan Relay 1 Control Circuit High Voltage
DTC P0693: Cooling Fan Relay 2 Control Circuit Low Voltage
DTC P0694: Cooling Fan Relay 2 Control Circuit High Voltage
Diagnostic Fault Information

is the ECT showing overheat, yes no?
if yes, it must operate a fan or 2.
the book even covers all tests for fans dead, in a large truth table.
both the FSM and alldata.com have that, its no secret ,its published in 4 major places.

lets back up
if the engine coolant is low (no that side tank the engine and rad)
the ECT will lie. if that happens the fans may not come one
that is because the ECT is useless measuring air, for water.
that water must touch ECT for ECT to work.
this is FIRST
then scan the ECT does it show overheating, IT must if it IS overheating. fix that next if it lies to you,(IR gun in hand)

The system has staged fans.
i cant find the trip points in my crappyy online pages.
but is like 225f then 250f trips. is my guess...
about. if the engine over heats, check fuses first then scan it.
it will simply tell you why its bad.
eg, fan1 output dead.
or if you hot wire a fan and its dead, then it is.
(only on cars with non modulated fans,,hot wire them,else not.)

now the link to the 4 buck real book.
the non dash XL7 (my guess) you this pick yourself... cant see car.
https://suzukipitstopplus.com/Products/10182-2007-xl7-service-manual.aspx

this is how it really works
the ECU has software that decide trip points for fans.
hard coded, this is. based on how hot it is and if A/C is on not.
its way smarter than 1988 and better.
the DTC errors can see an open line, shorted to ground or stuck 12v.(runs all time error)
(tells you relay is good or not)

25839272-0kjd5huq4lpr130nt243wle5-3-0.jpg no scanner no joy , sorry, tis a fact.....

25839272-0kjd5huq4lpr130nt243wle5-3-2.jpg
0helpful
2answers

2004 Chevy Monte Carlo 3.4 the a/c stopped blowing,then it started overheating to the red within a couple miles,replaced the thermostat,the relay switch some days it overheats sometimes it runs fine

Are the cooling fans coming on ? What relay switch did you replace ?
The BCM will request low speed cooling fan operation from the PCM under the following conditions:
?€¢
Engine coolant temperature exceeds approximately 103?°C (217?°F).


?€¢
When A/C is requested and the ambient temperature is more than 10?°C (50?°F).


?€¢
A/C refrigerant pressure exceeds 1310 kPa (190 psi).


?€¢
After the vehicle is shut off if the engine coolant temperature at key-off is more than 117?°C (243?°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.


The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the PCM to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the engine wiring harness junction block. The ground path is provided at G101.
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the FAN CONT #1 relay coil, closes the relay contacts, and supplies battery positive voltage from the FAN CONT #1 fuse through the cooling fan motor supply voltage circuit to the right cooling fan. The ground path for the right cooling fan is through the FAN CONT #2 relay and the left cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the FAN CONT #1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the FAN CONT #2 relay and the FAN CONT #3 relay through the high speed cooling fan relay control circuit. This energizes the FAN CONT #2 relay coil, closes the relay contacts, and provides a ground path for the right cooling fan. At the same time the FAN CONT #3 relay coil is energized closing the relay contacts and provides battery positive voltage from the FAN CONT #2 fuse on the cooling fan motor supply voltage circuit to the left cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
Is your vehicles check engine light lit ?
Is the

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1answer

Where is the radiator fan switch located on a 2002 oldsmobile intrigue

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood accessory wiring junction block. The ground path is provided at G113. The relays are located in the underhood fuse / relay box .
So ,what's the problem Paul , car overheating ? Fans not working ?
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 fuse through the cooling fan motor supply voltage circuit to the right cooling fan. The ground path for the right cooling fan is through the cooling fan 2 relay and the left cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan 3 relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 2 relay coil, closes the relay contacts, and provides a ground path for the right cooling fan. At the same time the cooling fan 3 relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the left cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
The PCM commands Low Speed Fans on under the following conditions:
?€¢
Engine coolant temperature exceeds approximately 106?°C (223?°F).


?€¢
When the A/C is requested and the ambient temperature is more than 50?°C (122?°F).


?€¢
A/C refrigerant pressure exceeds 1310 kPa (190 psi).


?€¢
After the vehicle is shut off if the engine coolant temperature at key-off is greater than 140?°C (284?°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.

The PCM commands High Speed Fans on under the following conditions:
?€¢
Engine coolant temperature reaches 110?°C (230?°F).


?€¢
A/C refrigerant pressure exceeds 1655 kPa (240 psi).


?€¢
When certain DTCs set.



So

0helpful
1answer

Overheating

CAR OVERHEATING FIRST CHECK FOR LOW COOLANT IN THE RADIATOR COOLANT OVERFLOW JUG.IF COOLANT LEVEL IN OVERFLOW JUG LOW REFILL ADD COOLANT BACK TO THE FULL COLD MARK.PUT RADAITOR CAP ON COOLANT OVERFLOW JUG START ENGINE LET IT IDLE UNTIL IT OPERATING TEMPERATURE.MAKE SURE TOP RADIATOR HOSE GETTING HOT WHILE ENGINE WARM UP.IF TOP RADIATOR HOSE DONT GET HOT WHILE ENGINE IDLING YOUR THERMOSTAT COULD BE STUCK CLOSE CAUSING CAR TO OVERHEAT.IF TOP HOSE IS GETTING HOT.CHECK FOR COOLANT LEAKS CHECK TOP RADIATOR HOSE AND BOTTOM RADIATOR HOSE FOR LEAKS.CHECK FOR LEAKS AT THE RADIATOR CORES AND PLASTIC SIDE CONTAINERS.IF ALL IS GOOD ENGINE OVERHEATING WHILE IN A LONG TRAFFIC LINE, COOLANT FANS NOT COMING ON.COULD HAVE FAULTY ENGINE COOLANT TEMPERATURE SENSOR OR BLOWN COOLING FAN FUSE OR RELAY.COULD HAVE PCM FAULT.MAKE COOLING FAN ELECTRICAL CONNECTORS AND WIRING NOT DAMAGE OR BROKEN.
0helpful
1answer

The truck is overheating every time the a/c is on but the thing is when the a/c is turning off and on every 10 seconds, and engine looses much power with a/c on... thanks

{: ) If the engine running performance is well and good without the a/c, observe the a/c compressor performance and cooling. A cycling compressor can be caused by high pressure on the discharge side. The higher the pressure, the more heat will be generated specially at the a/c condenser. Engine overheating and poor a/c cooling has one common factor: the engine cooling fans. Normally when you turn on a/c, additional load and heat will stress the engine. For the cooling fans, there is a low and hi speed. If these cooling fans do not operate at precise timing and speed, the heat generated by the condenser and radiator will combine and rise up to a critical level. So better check carefully the condition and operation of your cooling fans. Check also the fan relays and fuses.
I just hope it's not a module issue, it will need more diagnostics, and very costly ,too.
0helpful
1answer

Crownvictorias2006 overheating all the time

Do you think that it's overheating because the temperature light is on? If so, then it's possible that you have a bad temperature sensor and not an overheating engine.
Look for other signs of engine overheating :
1. Sluggish engine operation.
2. Detonation upon acceleration (pinging).
3. Rough, uneven engine idle.
4. Coolant boiling in overflow tank.
If your vehicle is experiencing these symptoms, then overheating is indicated. One of the most common cases of overheating is a bad thermostat. Another common problem is a faulty cooling fan or fan circuit. The cooling fan can be checked by running the engine at operating temperature and turning on the AC control. if the fan does not come on, then a problem with the fan circuit is indicated. The thermostat can be checked by placing a cooking thermometer on the motor near the upper radiator hose where it attaches to the motor. the temperature should not go above 225deg. If it does, then replace the thermostat. If the temperature stays at or below this rating, then replace the temperature sensor. I hope that this information helps you with your problem and thank you for using Fixya.com.

WARNING : Be very careful when working around cooling systems when the engine is at operating temperature. DO NOT open the radiator cap (if equipped) or even the overflow tank cap when the system is hot. Always wear safety glasses. Remember that electric cooling fans can operate at any time, even after the engine is off. Keep hands away from fan when working in the engine compartment.
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1answer

02 sunfire overheating

make sure you have radiator full of coolant
run the car to operating temperature
check the operation of the cooling fan
feel the upper radiator hose and the lower radiator hose. they both should be hot.
if one is cold then you may have a bad thermostat or restricted flow
if cooling fan does not come on when engine is hot then you have bad cooling fan switch, relay or motor.
good luck
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1answer

Overheating

Your overheating problems can have several possible causes.
1) Airlock in heating system - solution - bleed air from cooling system.
2) Radiator blocked - solution - drain and flush radiator
3) Failed waterpump - solution - fit new waterpump
4) Engine thermostat stuck in closed position - solution - fit new thermostat
5) Electric cooling fan (if fitted) failing to operate - solution - check fan, fan operating switch, all wiring and connectors
6) Not enough coolant in system - solution - check and top up to required level. Also check all hoses for sign of leakage.
7) Faulty temperature gauge giving incorrect reading.
2helpful
1answer

Overheating

Here are the cooling system diagnostic steps...First does the cooling fan kick on (with engine hot)? If not, check the fuse, if good then check the thermoswitch in the radiator (it's about an inch and a half in diameter located on the lower part of the radiator with two wires ) by disconnecting the wires and touching them together (again, with engine hot...at least 190 degrees) if the fan comes on, you have a bad switch. If not connect a 10 gauge jumper wire from the battery to the fan itself (there are three terminals,,, one high, one low and ground). With power direct from the battery (and a ground wire, if necessary) fan should run... if not replace the fan assembly... if it does run then you have a bad cooling fan relay. If the cooling fan system is working normally and you still are overheating, the next thing to check is for coolant flow. let the engine cool and remove the reservoir cap and start it and let it run to operating temp. The upper hose should warm up and you should see a thin stream of coolant entering the reservoir... if not let it cool again, raise the vehicle, place a drain pan beneath the engine and remove the T-stat from the housing and button it back up. run again to operating temp... if you now have flow, and it doesn't overheat it was the 'stat. If it still overheats look at the water pump... is it noisy while running? is it weeping coolant? if so replace the pump. if not it's time to suspect a radiator blockage... try backflushing, if it seems to take alot of pressure and very little come out the other outlet the radiator is at least partially clogged and should be rebuilt or replaced... Hope this helps...;-)
0helpful
1answer

Overheating problem, the cooling fan does not operate

Everyone keeps ignoring clutch fan on water pump. If it does not lock up when engine is hot, only the electric fan will be operating. With the undersized radiator used on Jeeps, it will cause overheating!!!
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