Question about 2001 Honda Civic

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Running on "H" intermitantly.

The radiator fan not running unless I put it on a/c and it will go back n forth from "H" to 1/2 way down and the heat runs hot and cold.

Posted by pamm on


5 Related Answers


  • 72 Answers

SOURCE: bottom radiator hose cold. upper radiator bulging.

The fan won't come on because the thermoswitch is in the bottom of the radiator, without coolant flow the switch never gets hot. Just because a part is new doesn't mean it is good, is the thermostat an aftermarket part ? I would take out the thermostat (leave the gasket) and see if the bottom hose gets warm. If the bottom hose does not get warm, you may have a blockage or bad water pump

Posted on Apr 18, 2009


David Melrose

  • 496 Answers

SOURCE: 2004 Odyssey, heat and A/C do not work unless van in motion

Since warm air eventually comes out when the vehicle is in motion, you may have an air mix door that is stuck in fresh or is somehow blocking warm air from the heater core.

To see if the air mix control motor is bad, you need to retrieve your Diagnostic trouble codes (DTC's) from the heater control panel. To run the diagnostic function, do the following:
1. Turn the ignition switch ON (II).
2. Turn the fan switch OFF.
3. Press the recirc control button to select Recirc (recirc light on.)
4. Press and hold the recirc button to select Fresh (recirc light off) and continue to hold the button down until the recirc light comes on for two seconds and then goes off.
5. If the system is okay, the recirc light stays off.
6. If there is a problem, the recirc light blinks the DTC to indicate the trouble. One blink=a problem in the air mix control motor circuit. Two blinks=problem in the mode control motor circuit
Three blinks=problem in evaporator temp sensor circuit.
7. Turn the ignition switch off to cancel the self diagnosis function. Run the diagnostic again after repairs are complete.

Note: the air mix control motor has a rod which connects to a plastic link. The link controls the mix doors and also connects to the heater control water valve via a cable. The air mix motor may check okay, but if the link is broken then you will still have problems. the motor is on the bottom of the heater unit in the front passenger's foot well.

Posted on May 11, 2009



  • 1 Answer

SOURCE: 92 honda accord is running hot but radiator fan is not turning

Connect the fan directly to the battery to test

Posted on Dec 08, 2009


  • 431 Answers

SOURCE: the radiator fan does not work and the car run

It will most likely be a Thermos fan switch if you go to parts store git a new one they can point out to you where it is located ,most of the time they are in the head near the thermostat ,but some times they are in the radiator hope this helps . IT could also be the relay,you could ground the thermo fan switch it should cause the fan to run then you will know that the relay is OK ,hope this is some help ,feel free to ask if we can be of any further assistance Thank you.

Posted on Mar 30, 2010


Colin Stickland

  • 22485 Answers

SOURCE: i have a 1999 honda civic lx its was running hot

iam suspecting the temperature gauge here ,something is or could be wrong with its electrical conductivity ,or the cooling fan is coming on too late which could be caused by a similar problem with the fan temperature switch

Posted on Feb 15, 2011

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1 Answer

Overheating when I sit idle.

Over heating the engine is a serious concern. With the hood raised you should hear the motorized fan turn on just behind the radiator as the engine requires additional cooling.. If you look in from the rear of the radiator you should see the fan blades.

This electric powered motor operates on a thermostat and when the engine temperature rises this fan should come on. I'm assuming from your description that when driving and air is flowing through the radiator as the car travels the engine is nor overheating.

Check fan motor thermostat, check fan motor and check wiring.

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Methods to trouble shoot
(1) check thermostat device. if thermostat is stuck - not working half the water used in cooling system is missing once engine heats up which can lead to over heating. (may need mechanic to check this)
(2) check radiator has water in it . if it is low there may be a leak in cooling system somewhere check rubber hose and radiator are not leaking.
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