Question about 2000 Daewoo Nubira

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Cooling fans on radiator will not run. Voltage in plug at block thermostat is 5.4.this therm provides an earth switch. Bypassed the thermo to earth and fan relay engages momentarily only. Relay is ok. changed it and problem still exists. Should the voltage at thermo plug be 5.4? What is likely to interupt the relay control circuit?

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The fan control thermo switch should be either "off" or "on".
Voltage should measure either +12 or 0V, depending on coolant temperature.
Replacing it should fix your problem.

Posted on Jun 20, 2009

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Our problem was to establish if we had a line resistance from the fan relay to the thermo switch or an intermittent earth connection. Neither was the answer.
We managed to locate a circuit diagram off the web and discovered that the fan relay is controlled by the ECM. The ECM gets data from the thermo switch and that is a 5 volt circuit.
We found a guy about 2 miles from where we are in New Zealand who has an electronics workshop who has had this happen before and repairs ECM's for a living. He will get it monday to do that.
THe original problem was that the two hoses that come from the block to the heater blew simultaeniously. Couple of plastic connectors broke. Fixed those and tested all fine and two days later popped the pressure cap. At this point found the radiator fans had been intermittent and finally failed completely. Cant find any other damage so will thow in a new thermo stat an a repaired ECM anfd go from there.
regards
Dave

Posted on Jun 20, 2009

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Where on the VG30 engine is the cooling system thermo switch situated?


fitted to nissan pathfinders... what year ?

if you cant find the thermostatic fan sensor for sale
or on or near the base of the radiator

I would say engine cooling fan runs from the ECU

the dash temp sender will be close to the thermostat housing

hint
you can fit after market cooling fan ...
with just an on/ off switch

Nov 25, 2016 | Cars & Trucks

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Cooling system fault finding..


Your cooling system works by pumping coolant(water and antifreeze) through the engine where it absorbs heat, through the radiator (where it loses that heat) and back into the engine.
Main components of the cooling system.
  1. Coolant. It can be plain water. Adding Glycol based antifreeze is definately recommended as it not only raises the boiling point of the water and lowers the freezing point but also contains very important corrosion inhibitors. Adding too much antifreeze lowers the coolant's effectiveness so don't go more than a 50/50 mix unless stated otherwise by the manufacturer.
  2. Radiator. This acts as a heat exchanger between the coolant and outside air. It is actually a whole bunch of small pipes that have thin pieces of metal conncted to them to increase the effective surface area.
  3. Waterpump. Well that's what it is. A pump to circulate the coolant around the engine.
  4. Thermostat. This unit regulates the flow of coolant around the system. You need to get the engine to operating temperature as quick as possible, then you need to keep it there as this aids in lowering fuel consumption and emissions and this is the job of the thermostat. It is installed in the system in such a way that it can block the flow of coolant between the radiator and the engine.
  5. Cooling fan. Cooling fans help airflow through the radiator at low speed or when the vehicle is stationary This may be electrical - powered by a thermostatic switch and a relay, directly driven by a belt off the crankshaft or have a viscous coupling. The viscous coupling is also directly driven but contains a fluid which couples the fan to the pulley only when needed.

Reasons for overheating :
  1. Insufficient coolant
  2. Insufficient circulation of the coolant
  3. Insufficient airflow
  4. Excess heat generation
Do's and dont's
When topping up it is better to use antifreeze only, as you will not be diluting the mixture. When refilling use the correct mix of water and antifreeze or fill with pre-mixed coolant.
Replace coolant according to service schedule.
Never open a hot cooling system.

Troubleshooting.
1./
The first and most obvious thing to check is coolant level.
No reservoir : coolant is added directly to the radiator. Fill to the top. You may find a little fluid missing everytime you open the radiator. This is due to water expanding when heated which escapes through the overflow pipe at the radiator cap.
Non pressurised reservoir. This coolant tank is not pressurised and can be opened at any time. Usually has a cap that just clips on. Fill to the max mark when the engine is hot or at least to the min mark when the engine is cold. If this reservoir is filled it does not nescesarily mean the system is full since it depends on expansion and contraction of air and coolant within the system to get coolant back into the radiator. The radiator should be filled as well.
Pressurised reservoir : Most modern-day vehicles are fitted with this type of system. It is pressurised and should only be opened when the engine has cooled down. Do not overfill, always keep coolant levels between the minimum and maximum marks.
If coolant levels keep dropping with no visible signs of leaking have the engine tested for a blown head gasket.

2./
The internal passageways that allow for coolant flow through the engine are metal and constantly exposed to coolant which causes rust which is transported throughout the system. The radiators' internal pipes have very small diameters and easily become blocked by this rust. This decreases the effective area of the radiator and the amount of water that can pass through it. Regular replacement of the coolant will prevent this build-up.
Waterpump impellers may break and decrease the efficiency of the pump although this is rare.
A slipping fan belt will also cause decreased coolant flow but is usually quite noticeable as a high pitched shrieking noise especially on startup and when revving the engine.
The thermostat is in effect a valve which opens and closes with temperature. They go faulty mostly because of rust and scale buildup and can get stuck in a closed or half-open position, thereby blocking waterflow to the radiator.

3./
The radiator fins are spaced closely together so can easily catch debris such as bugs and grass which will impede airflow through the radiator. The fan assists with airflow so if not working will see the engine overheat when stationary or in stop-start traffic. If the engine cools down while driving above 35mph this is the obvious starting point.

4./
Incorrect fuel/air mixture and incorrect ignition timing may cause the engine to generate heat in exess of the coolings systems' capabilities.


How to test and repair :
  • Check the fluid level. Also check for leaks. They will usually show up as brown or green streaks of dried coolant.
  • Check your fan belt/serpentine belt - is it still intact? Check the operation of the fan. On a direct coupling you should not be able to move the fan. A viscous coupling should not spin freely by more than a quarter turn. See below for the electrical fan.
  • Flush the system. Remove the upper and lower radiator hoses and if possible, remove the radiator. Stick a hosepipe into the outlet side of the radiator and let the water run until it comes out clear on the other side. Then repeat the process with the hosepipe in the inlet side. Continue with this until the water runs absolutely clear.Now remove the thermostat from the engine and do the same to the engine. Clear the radiator fins of bugs and debris.
  • Check the thermostat. It should be in the closed position. Drop it in a cup of boiling water and you will notice it opening. Since it is already out you may as well replace it since it is relatively inexpensive
Electric fan
On an electric radiator fan, let the vehicle heat up to just before overheating. If by this time the fan has not come on switch off the engine.Locate the cooling fan fuse and check that it is intact. Using a multimeter, measure between each of its' contacts and earth. See diagram. Measure between 1 and earth(bare metal point on vehicle body or on battery negative), and then between 2 and earth. Both readings should be 12V or more with the ignition on. If 1 reading is found only, the fuse is faulty. If no reading is found the wiring between the ignition and fuse is faulty.

cae4905.jpg
Now check the operation of the fan itself. Disconnect the fan. Connect a lead wirefrom the battery negative to one of the fan connector pins and from thebattery positive to the other pin. See diagram: 1 - Fan motor
2 and 3 - Connect directly to battery

e22f230.jpg

This is a DC motor so polarity doesnot matter. If the fan operates reconnect it to the harness. If not, replace the fan.
Locate thefan relay. You will need a multimeter to test. Remove the relay. Switch on the ignition. Measure voltage at allthe connections in the relay socket to earth. Two of them have to be at 12V or more. If not, the problem is between thefuse and the relay. Re-insert the relay.
Disconnect the thermoswitch. Usually located on the radiator. See photo : 1 - Thermostatic switch. 2- Leaked and dried coolant on a neglected radiator.
c67d5ab.jpg

Shortcircuit the 2 wires from the harness that were a moment ago connected to the thermo switch.(With a single wire thermo switch the wire needs to be connected to earth or battery negative). Switch on the ignition. The fan should start running again. If not switch off the ignition and remove the relay again. You already know the connecting point with 12V. Measure the other 3 wires for resistance to earth. One of themshould read more than 5 ohm. Connect a lead between the "12V" connector and the "5ohm" connector. Switch ignition on. If the fan runs the relay is faulty. If not the wiring between the relay and fan is faulty.
Simplified wiring diagram:
A- Battery
B - Ignition Switch
C - Fuses
D - Relay
E - Thermostatic switch
F - Radiator fan


a69a9d5.jpg


Leak detection
The most obvious tell-tale would be a puddle of coolant under the vehicle after a trip. Don't confuse this with condensation dripping from the aircon.
Inspect pipes for cracks and leaking at joints.
Inspect the radiator for dried coolant. (See photo above)
Inspect the engine block for coolant streaks. Leaks can start on the block itself through the welch plugs which are also constantly exposed to coolant.
Another leak point is the water pump shaft seal which cannot be repaired. Replace the whole pump.
Remember that the cabin heater is plumbed into the cooling system and can also leak. Wet carpeting in the footwell is indicative of this although such wet carpeting may also be the result of condensation from the A/C.

How to wire a relay

on Sep 17, 2010 | Nissan Sentra Cars & Trucks

1 Answer

Cooling fan problems


hi there . there are lots of causes. head gasket. blocked radiator.
air lock. stuck thermostat. check that your fan is actually switching
on and off. if not check the thermo switch on the engine.

Feb 01, 2014 | 1998 Toyota Corolla

1 Answer

I just bought a 1995 jetta and it's running at 260 degrees. Is this too high, and if it is then what would be causing this?


CHECK TO SEE IF BOTH COOLING FANS RUNNING ARE RUNNING WHEN ENGINE RUNNING START OVERHEATING IF COOLING FANS NOT WORKING CHECK COOLING FANS LARGE FUSES IN THE ENGINE COMPARTMENT OR YOU COULD FAULTY COOLING FANS THERMO SWITCH BOTTOM LEFT SIDE OR RADIATOR.IF COOLING FANS IS WORKING WHILE ENGINE RUNNING.RADIATOR CORES AND HEATER CORE COULD BE CLOGGED.COOLANT SYSTEM NEED FLUSHING. THE THERMOSTAT PARTIALLY CLOSED CAUSE ENGINE OVER HEAT.CHECK WATERPUMP WEEP HOLE IF LEAKING WATER PUMP NEED REPLACING.

Jul 21, 2011 | Volkswagen Jetta Cars & Trucks

1 Answer

Overheating water comeing out of bottol


REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP.CHECK MECHANICAL COOLING FAN.SHOULD HAVE RESISTANCE WHEN TURN WITH HAND.IF FREEWHEELS FAN CLUTCH NEED TO BE REPLACED.CHECK TO MAKE SURE AUXILIARY ELECTRIC COOLING FAN RUNNING HOT WIRE COOLING FAN IF FAN RUNS.YOU HAVE FAULTY THERMO SWITCH LOCATED AT THE BOTTOM OF RADIATOR ON THE LEFT HAND SIDE ON 4 CYLINDER ENGINE FOR V6 ENGINE THERMO SWITCH LOCATED ON THE LOWER RADIATOR HOSE ON THE RIGHT HAND SIDE OF THE ENGINE COMPARTMENT. CHECK FOR BLOWN COOLANT FAN FUSE OR FAULTY RELAY.IF THE AUXILIARY ELECTRIC FAN DONT RUN WHEN HOT WIRED THE ELECTRIC FAN FAULTY.

Jan 03, 2011 | 2000 Audi A6

1 Answer

ENGINE OVERHEATING


Do the fans come on when the engine overheats? If so nothing wrong with the circuit and the thermostat(not thermo switch!) or radiator is to blame.
Test the fan. There are 2(if you have A/C fitted) Disconnect the electrical plug from the fan. Run 2 wires from the battery straight to the fan and see if the fan comes on. (Be careful when connecting not to short circuit the wires. Theres a lot of power in the battery!) Polarity does not matter. This is a direct current motor so reverse polarity will only make the fan turn in the wrong direction. If the fan turns reconnect its electrical connection and move to the next step.
To test the fan circuit locate the thermo switch. It is on the bottom right of the radiator and has 2 wires connected. disconnect the electrical plug and short circuit the 2 wires by inserting a piece of wire into the connector with the ignition on. The fan should come on. If it does the thermo switch is at fault and needs replacing.
With the electrical sorted there is not much else. Like I mentioned it is either the radiator(blocked) or the thermostat(sticking)
Radiator can be taken to a service centre and have them clean it out for you. The thermostat cannot be repaired and needs to be replaced. It can be removed and the engine will still operate, but just take longer to warm up. I'm not sure on the '99 model, but it is usually located on the right hand side of the engine at the bottom on the water pump housing.

Jul 07, 2010 | 1999 Volkswagen Jetta

1 Answer

Temp gauge goes high. Radiator leak just the


It could well be a faulty thermostat- test or replace same.
Could also be a blocked radiator core, - check coolant or airflow is not restricted,
Ensure any radiator leaks are repaired,
Ensure coolant level is correct, without airlocks - bleed as necessary on re-fill,
Check operation of cooling fan - ensure fan runs at appropriate engine temperature - if not check sensor switch and associated relay operation.
Thermostat is located at the end of top radiator hose where it connects to engine housing.

Aug 10, 2009 | 1995 Jeep Grand Cherokee

3 Answers

96 Acura RL overheating.


have you changed the thermostat? located at upper hose opposite radiator end in the gooseneck (usually 2 screws) make sure you buy a gasket or gasket making compound if changing. most overheats occur due to stuck thermostat (doesn't open to cool) you could pull tstat out for temp fix but it wouldn't heat well in colder weather

Aug 05, 2009 | 1996 Acura RL

1 Answer

98 Celica overheating problem


c7d7b55.jpg Cooling Thermostat.
Look along the radiator hose where it enters the engine. This controls the water temperature.


toyotacelicathermalfanswitch.jpgToyota Celica Thermal Fan Switch The Toyota Celica thermal radiator fan switch is usually located in the radiator or the engine block and has 2 or 3 wires coming from the unit. The 3 wire switch has a dual sensor for dual speed radiator fans. The Toyota Celica thermo fan switches come in the factory temperature settings and also come in cooler thermostatic settings so the fan will come on at a lower coolant temp.

The Toyota Celica cooling system is made of aluminum components and requires a Phosphate free coolant. DO NOT PUT an over the counter antifreeze in your Toyota Celica, as it will ruin the radiator and water pump.

Feb 19, 2009 | 1998 Toyota Celica

1 Answer

Intermitant temperature


Check to make sure your thermostat works right by monitoring the warming up of your engine. With a completely cold engine, start and run the engine for a few minutes, then put your hand on the top radiator hose to monitor if and when it gets warm as the thermostat opens more and more and note the gauge reading( if it works) the top radiator hose should be unbearably hot within 5-8 minutes. If the therm. opens right it should close right aswell, staying open a little while eventhough the radiator may have cooled may be what you are experiencing causing the rapid cooling and is nothing to worry about. The Hose should not get warm very soon after starting the engine. Regarding you gauge, lets take one step at a time, verify proper op. or the therm.

Jan 20, 2009 | 1986 Toyota 4Runner

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