Resistance power of 20 amps indicate whether it is good or faulty.
To test a thermostat using a multimeter, set the multimeter to the resistance or ohms setting. Disconnect the thermostat from the power source and remove it from the appliance. Place the multimeter probes on the thermostat terminals. A functioning thermostat should show a specific resistance reading. If the reading is significantly different or shows as infinite resistance, the thermostat may be faulty.
Thermostats are not electrical devices so I am assuming you are referring to a temperature sender. To test it unplug it with the motor off and cold and use an ohm meter between the two connections on the sender, it should show infinite ( closed circuit ) resistance. Plug the sender wire plug back on and start the motor. Let the engine run until it is warmed up. Shut off the motor, disconnect the sender again and retest with the the ohm meter, the resistance should drop and show an open circuit. Note that if this sender is a thermo time switch the test I described will be incorrect. If you really are trying to test a thermostat the way you do it is take it out of the car ( with engine cold )and look at it. If it is not closed it is faulty. Put the thermostat in a pan of water and heat it up while monitoring a thermometer to the temperature stamped on it. If it does not open at the designated temperature it is faulty. I would suggest you buy a repair manual for your vehicle to help you identify wich parts you need to test. Most of them have troubleshooting tips and tables to help you figure out what is wrong with your car.
There could be many reasons. Not enough coolant or bad flow, faulty thermostat, low oil. If the coolant freezes then it will overheat. If your car continues to overheat then you should have the coolant flushed and thermostat replaced.
check with meter to see resistance value (ohms)should read 3.4
To test a thermostat remove it while the motor is cold and make sure it is not stuck open. If it is stuck open when cold it is faulty. If it it is closed put it in water on a stove with a thermometer and heat the water. It should open at the temperature it is rated for wich is usually stamped on the thermostat. If it does not open when heated it is faulty. Thermostats are cheap and do need to be replaced occassionally; if I decide to remove a thermostat i generally replace it with a new one for piece of mind.
If your doing a lot of city driving you should get it fixed... the thermostat tells the cars computer when to turn on the fan which provides more the 50% of your engine's cooling in city driving!
I would verify the coolant temp with an infrared temp gun. Point the gun at the thermostat housing when engine is running and fully warmed up. It should be in the 195 degree F zone. If so then I would suspect a faulty temp gauge sending unit. If the temp doesn't reach 195 degrees F with the gun, I would suspect a faulty thermostat. Be sure the coolant level is correct also.
Coolant system leak, faulty thermostat, lack of (or long overdue change of) engine oil... low fluid or bad thermostat, low oil, bad radiator,clogged water pump. You should also make sure that the radiator and a/c fans are working propperly
First check that the refrigerator's thermostat is set to the correct temperature. If it is then your refrigerator is faulty and needs repairing or replacing.Please do not eat any food that has not been held cool enough.
Thermostat is a mechanical device that reacts to heat. As heat is applied the thermostat contracts and allows water to flow through the system. A thermistor is a thermal resistance sensor that also reacts to heat. There are two kinds, one is a negative coefficient and is a positive coefficient. As heat increases it changes the resistance value of the thermistor. That resistance value is transmitted to the computer and/or temperature gauge. Through computation the computer can can tell what temperature the engine is at to make decisions on how it should be run.
You should use a thermostat gasket along with the thermostat housing ring. The gasket should be replaced every time the thermostat housing is opened.
There could be several problems including a faulty thermostat, low coolant, a bad water pump, or an operable radiator, or leaky hoses. Narrow these down and you should be able to find the problem.