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No heat? 95 Civic

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Old Jan 5, 2009 | 09:14 PM
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Default No heat? 95 Civic

My heat is ice cold but the hoses going to and from the heater core are hot. Can it be anything other then a bad or blocked heater core? Also I can not smell antifreeze inside the car so I know the heater core is not cracked.
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Old Jan 5, 2009 | 09:26 PM
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Post Re: No heat? 95 Civic

Your heater core might be plugged... You can manually unclog it but it includes discharging your air conditioning and recharging it later (not something most people have the equipment to do).
Try this: swap the inlet and outlet hoses to the heater core. This will backflow it and might just remove any soft deposits plugging it. The two hoses might be of different diameters, so I had to force one of them to go on, and really clamp down on the other one to prevent leaks. Drive the car for 5 mins and the results will be instant. park the car immediately, let it cool, and drain the cooling system. Swap the hoses back put in new fluids and there yah go. Hope this helps
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Old Jan 5, 2009 | 09:33 PM
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Default Re: No heat? 95 Civic

Originally Posted by Anti_AM_
Your heater core might be plugged... You can manually unclog it but it includes discharging your air conditioning and recharging it later (not something most people have the equipment to do).
Try this: swap the inlet and outlet hoses to the heater core. This will backflow it and might just remove any soft deposits plugging it. The two hoses might be of different diameters, so I had to force one of them to go on, and really clamp down on the other one to prevent leaks. Drive the car for 5 mins and the results will be instant. park the car immediately, let it cool, and drain the cooling system. Swap the hoses back put in new fluids and there yah go. Hope this helps
The car is not a dd so it does not have a/c. Would this pose a problem by pushing the blockage into the motor?
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Old Jan 5, 2009 | 09:35 PM
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Default Re: No heat? 95 Civic

also the thermostat is a year old
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Old Jan 6, 2009 | 04:53 PM
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Default Re: No heat? 95 Civic

Sounds like a vent/blendoor problem, if both heater hoses are hot it would indicate coolant is flowing through the heater core.

Easy enough to check, remove heater hoses, jerry rig a garden hose up to the heater core return line, turn on the tap, it will flush anything out that may be there, [without flushing it into the motor or rad], if water flow is good, then heater core is good.

What is the air flow like, [at all speeds] when heat is on and you switch from vents to floor to defrost?

Can you hear the fresh air/recirculate door opening and closing?

Is there any noticeable diff. when you switch from hot to cool to hot?94
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Old Jan 6, 2009 | 05:07 PM
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Default Re: No heat? 95 Civic

Originally Posted by fcm
Sounds like a vent/blendoor problem, if both heater hoses are hot it would indicate coolant is flowing through the heater core.

Easy enough to check, remove heater hoses, jerry rig a garden hose up to the heater core return line, turn on the tap, it will flush anything out that may be there, [without flushing it into the motor or rad], if water flow is good, then heater core is good.

What is the air flow like, [at all speeds] when heat is on and you switch from vents to floor to defrost?

Can you hear the fresh air/recirculate door opening and closing?

Is there any noticeable diff. when you switch from hot to cool to hot?94

^^^what he said^^^
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Old Jan 7, 2009 | 08:16 AM
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Default Re: No heat? 95 Civic

i take it you have looked at the coolant level?
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Old Jan 9, 2009 | 12:10 AM
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Default Re: No heat? 95 Civic

Originally Posted by fcm
Sounds like a vent/blendoor problem, if both heater hoses are hot it would indicate coolant is flowing through the heater core.

Easy enough to check, remove heater hoses, jerry rig a garden hose up to the heater core return line, turn on the tap, it will flush anything out that may be there, [without flushing it into the motor or rad], if water flow is good, then heater core is good.

What is the air flow like, [at all speeds] when heat is on and you switch from vents to floor to defrost?

Can you hear the fresh air/recirculate door opening and closing?

Is there any noticeable diff. when you switch from hot to cool to hot?94

I did the thing with the hose and there was no blockage in the core. The air flow is strong in all of positiong and all of the speeds. Yes, I can hear the door moving. No, there is no difference when I change it from hot to cold and I made sure to check first to see that my control valve was working properly.

I am out of ideas it just doesnt make sence. If anyone has anymore ideas please feel free to add them.
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Old Jan 9, 2009 | 05:12 AM
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Default Re: No heat? 95 Civic

its got to be in your blend door....I have seen the cables fall off and I have seen the door arms break....if this is the case, you might be able to rig the door into the heat position so it stays open until you have time to remove the dash and replace the broken parts
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Old Jan 9, 2009 | 06:10 PM
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Default Re: No heat? 95 Civic

Whats the blend door?
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Old Jan 9, 2009 | 07:42 PM
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Default Re: No heat? 95 Civic

when you slide the lever from cold to hot, it has 2 cables attached to the control head...one goes to the water valve you see in the engine bay, the other goes to the blend door arm. it controls the temp of the vent air by controlling how much air is pushed through the heater core/evaporater or pushed around the core/evaporater. if you follow the cables it should take you right to it. it will be on the passenger side floor board. sometimes the cable can pop off of its nipple leaving you with no control of the heat. once you locate it, slide the lever back and forth a few times and watch the action, make sure you see and hear movement of the door.

BTW I think honda actually calls it the air mix door
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Old Jan 11, 2009 | 10:55 AM
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Default Re: No heat? 95 Civic

What about the cable on the water valve itself? Is it actually connected and opening the valve when you move the slider to hot?
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Old Jan 11, 2009 | 02:51 PM
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Default Re: No heat? 95 Civic

well he said both hoses were hot, indicating that coolant is passing all the way through the core and back out....if the valve was shut that would not be the case
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