Heat Blows Cold

[Mac-MerC]

While the car is in motion it blows hot air... but when i come to a stand still cold air comes out the vents. the air blows out the correct vent that i have it set on. the floor board on the passenger side is not damp.... so i dont believe its the "heater core".. (thats what had happened in my chevy back when before the heat went)
does anyone have any suggestions on what it might be. they will be greatly appreciated.

[Ozark Marauder]

Run the self test.



The temperature inside the car should be between 40 & 90 degrees.
With the car running.
Press the OFF and Floor buttons at the same time, then press the AUTOMATIC button within 2 seconds.
The display will show a pulse tracer going around the center of the display.
The test can run as long as 30 seconds.
Record all the DTC(s) displayed. Diagnostic Trouble Code = DTC


Post what you find.

[Curless]

If it works fine going down the road I would check your coolant level, if its low, at idle it wont push enough coolant through the heater core. The other thing to check is the vacuum line that feeds the heating ducts of the dash. Its located right in the back of the engine and some times they crack or burn on the egr passage.

[Mac-MerC]

Did the test three times and the same images appeared on the screen
sorry the pic is so big, dont know how to resize it.
http://i829.photobucket.com/albums/zz212/Mac-Merc/IMAG0996_zpsa6fd1360.jpg

coolant level is fine. all hoses near the egr are fine. didnt see any cracked, loose, or any that look.. messed up.

[tbone]

I could never get the self test to work either.

[rocky]

this cured my EXACT problem

jack car up in front at least getting wheels a few inches off ground
remove plug from crossover tube by alternator, think its 1/4 inch drive
fill until completely full then replace plug and let down.
If its a coolant level that should take care of it, like I said it did mine a few months ago when I replaced the thermostat and it Looked like my coolant levels were ok but I still had air in that tube.

[fastblackmerc]

You could have air in the cooling system or maybe the EATC o-rings need to be replaced.

[Mac-MerC]

i'll try the lift suggestion tomorrow

[a_d_a_m]

I was thinking it was a blend door actuator but if you're not getting a 3-digit code (not 888) then...I'm stumped.

[InglewoodAwk]

When I park mine on uneven ground with one side of the car lower than the other, she blows cold. Haven''t looked at anything yet. Just something I've noticed over the past few weeks.

[Mac-MerC]

Oh i burped the system.... hasn't blown cool air since. It drank up a lot of coolant, so im assuming that was the issue.

[JimmyXR7]

You could have air in the cooling system or maybe the EATC o-rings need to be replaced.
If you have not yet replaced the EATC o-rings, they are likely starting to leak. When the engine is running faster there is more pressure differential and the EATC would work (if the o-rings are just starting to leak). Jim