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2.3L 4cyl or 3.0L V6, 6th Generation

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1998 Honda Accord 4 cyl. heater blowing cold air

Checked antifreeze, radiator is full....Started, let heat up 15 minutes.........Temp gauge went up to normal & stopped....Top hose is hot, bottom hose is Not .....I also try to switch the air directional controls but Cold air keeps blowing out of top vents into my face...Any ideas?

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@acura "op hose is hot, bottom hose is Not" means the antifreeze is not flowing through. This can be caused by :

  • clogged heater valve
  • faulty air mix door
  • heater valve cable adjustment

Here is the part of the SM that deals with the HVAC of your vehicle model. Check your heating system accordingly 98 02 Accord HVAC

Update (12/18/2022)

Here is the test for the mode control motor

NOTE: Before testing the motor, check for HVAC DTCs (see page 21-101).

1. Disconnect the 7P connector from the mode control motor.

Incorrectly applying power and ground to the mode control motor will damage it Follow the instructions carefully.

2. Connect battery power to terminal No. 1 of the mode control motor, and ground terminal No. 2;the mode control motor should run, and stop at Defrost. If it doesn't, reverse the connections; the mode control motor should run, and stop at Vent When the mode control motor stops running, disconnect battery power immediately.


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I3. If the mode control motor did not run in step 2, remove it, then check the mode control linkage and door for smooth movement.

  • If the linkage and door move smoothly, replace the mode control motor (see page 21-62).
  • If the linkage or door sticks or binds, repair them as needed.
  • If the mode control motor runs smoothly, go to step 4.

4. Measure the resistance between terminals No. 5 and No. 7 of the mode control motor. It should be between 4.2 and 7.8 kO.

5. Reconnect the mode control motor 7P connector, then turn the ignition switch to ON (II).

6. Using the backprobe set, measure the voltage between terminals No. 3 and No. 7 of the 7P connector.

Vent: About 0.5 V

Defrost: About 4.5 V

7. If either the resistance or the voltage readings are not as specified, replace the mode control motor (see page 21-62).

f you find you have no power going to it, check the #56 in the fuse box inder the hood and check #3 and #13 in the fuse box under the dash.

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I'm thinking it might be the thermostat......


@acura if it would be the thermostat the top hose would not be getting hot water either.


I checked the Passenger side air mix motor and it was not moving, bought another , plugged it in and it's not moving......Continues to blow cold air out of the top vents, will not switch air flow either....


@acura you did check your heater vlave to see if it adjust? I'd try to flush the heater core. See if there is a bloackage in it


I'll check the heater valve tomorrow, if the heater valve is not working would that make air mix motor not work?......What has me puzzled right now is why the air mix motor on passenger side is not moving after i put another on there?


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sam sera éternellement reconnaissant.
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