99 ex sedan d16y8. Im not sure if it is just from being really cold outside or not so figured I would ask for more insight. My heat isn't very hot anymore, it blows out lukewarm. My temperature when driving operates at normal temperature but once the car sits, it drops down to the Cold side and then reheats when driving. thermostat is open, coolant is topped off, no leaks, rad is in goodshape. Any ideas? Thanks

 

thermostat is possibly stuck open.

 

Any way to tell besides replacing?

 

And when i say car sits i mean if im at a stop light or waiting in a parking lot with the car still on. Lol

 

fluctuating temps are a clear indicator. at this point might as well replace it anyway, it is a wax part that is 13 years old.

 

i used to have this same problem but in reverse when i was driving it would go cold and sit halfway warm when it would sit. it was blowing by the seal in the thermostat.... id replace the thermostat as they are cheap and an easy fix and see if it works.

 

Awesome guys thanks!

 

After you install a new OEM thermostat, bleed the cooling system.

Bleeding the cooling system may take 20-30 minutes.

1) Park the car on an inclined driveway with the front end higher than the rear.

2) Push/turn the dash heater lever/**** to MAX heat. Fan need not be on.

3) Follow the directions in the diagram below