Heat only works in high? Thump noise?

[hockeyadc]

So I think this may be some sort of vacuum or solenoid issue, however I'm not 100% sure. In my 2002 XLS, the heat does not work unless I turn the blower to high. When I do this I hear a loud "thump" behind the dash and the heat works fine. I've replaced the blend door actuator and the issue is still happening...

Any ideas?

Edit: Could it be the actual blend door itself? I really hope not, because I believe I have to remove the entire dash in this case...

 

[mbrando1994]

The blend door actuator is located on the driver side, the blend door is located on the passenger side. (on most models). The blend door only adjusts the temperature of the air rather than the speed of flow. I do need a little more information to diagnose this though.

When the setting is on 4, or the highest setting, is the thumping constant? Or just once as the motor kicks on? Can you adjust the heat from hot to cold while on the highest setting?

Do the other settings work as they should with the cold air? Proper speed, etc.? It does sound like an issue with the blend door, but it could be a few other things as well. I would bet on the door itself being faulty. Now the service manual does detail that dashboard removal is mostly necessary to replace the actuator, although I did replace mine with no cutting and only removing the panels below the steering wheel and center console. My service manual unfortunately does not say anything at all about either parts. I recommend some youtube videos to help, dashboard removal may not be necessary but if it is, have a partner and get it done, together it's not a hard task and well worth the hassle to save $400 and upward

 

[hockeyadc]

It is a one time thump as soon as I put it on high while the temperature is on heat, not constant. I had the constant clicking before, and replaced the blend door actuator about a year ago. The thumping sound just started happening, so I replaced the blend door actuator again but it doesn't look like that solved the problem. When I try and change the temperature from hot to cold after the thump noise, it doesn't change....

 

[Sweersa]

Not sure about the thump, but generally when the blower only works on high, it's a resistor issue and it needs to be replaced.

 

[hockeyadc]

Well the blower works on all settings its just that it's not hot until I put it on high first and get that thump noise.

 

[tuik]

Hi, did you ever get an answer or a fix for this. I have an 03 Explorer that is doing the exact same thing?