Hi,

New member here... trying to get some information to help troubleshoot my wife's 1998 Honda Accord EX heater issue. Up until about a week ago, everything with the heater worked fine... then all of a sudden barely any heat. The car stays at a normal temperature, so I tried flushing out the heater core. Although that seemed to help for a day or so, the heat got cold again. Next step was to replace the thermostat, which again helped for a while then the car got cold again. Following the thermostat, I decided to check the heater control valve, which seems to be working perfectly fine. I've also taken the air mix motor off and that is working well also. All of the "behind the dash" stuff seems to work... switches from defrost to vent to floor without any issue.

So here's what I know... The car seems to get up to normal operating temperature just fine, and stays at a constant normal temperature. When driving around, the heat works somewhat, but starts getting colder at idle. There doesn't appear to be anything mechanically wrong, but every time I've done work requiring draining the system and adding coolant back to the radiator and puke tank, it functions better and then we lose heat after a couple of days.

I've been told this could be a water pump issue, that it's getting too weak to pump enough coolant through the heater core... but I would have though by now the car would have at least ran somewhat warm by now... but it stays at normal operating temperature even when running for hours. Has anyone ran into this issue or have any suggestions? Is the water pump on its way out? Another mechanical issue I'm not thinking of?

Sorry if this is obvious... I didn't spend hours searching the forum... I've already spent hours taking it apart and putting it back together.

Thanks!

 

On my 1995 Accord I found out the blend door was the issue with getting proper heat. I looked up parts on Majestic and your 1998 has the same components. If the heater hoses coming out of the firewall are good and hot when your car is warmed up it is most likely you need to adjust the blend door cable. On my Accord I eliminated the heater control valve after finding out the heat and AC worked perfectly without it.

 

Heater hoses are hot... what part number is that? Where can I locate? thanks!

 

The 1998 Accord doesn't have an air mix control cable like a 1995. It has the air mix control motor with rods attached to the air mix control linkage.

In addition, only 1994 and early 1995 Accord had an adjustable air mix control cable; mid-year 1995, 1996, and 1997 (5th generation) Accords came with a non-adjustable air mix control cable.
https://www.hondaaccordforum.com/for...97-accords-jpg

 

The heater valve cable on a 1998 can be adjusted; however, your problem sounds like it is due to something else since you stated that "when driving around, the heat works somewhat, but starts getting colder at idle".

 

The heater control valve is fully opening, and the air mix motor is working and I verified that the rod and plastic piece are both opening when you turn the thermostat to hot.

 

I looked up the parts on Majestic Honda and they were the same part number for both years.

 

Look again. A 1998 has an air mix control motor, a 1995 does not.

Both cars have a heater control valve cable. However, a 1998 does not have an air mix control cable. The OP even stated more than once he has an air mix control motor.

 

I didn't realize the OP car is an EX.

 

Other 6th generation Accord trim levels (e.g. DX, LX) also had an air mix control motor, etc., not just EX.