Climate control trouble

[jabinya]

My interior heater blower fan switch only operates on the highest fan setting #4. The first three fan speeds don't operate the blower at all. Tried switching to a different blower with the same result. It worked on all settings in the past.

 

[luv2rallye]

Either your blower switch or blower resistors are bad.

 

[jabinya]

How would I determine which one is causing the problem? Blower resistor? Is that attached to the AC evaporator box under the dash?

 

[luv2rallye]

Most likely the blower resistor is bad which is behind the glove box. If you have A/C, it's on the blower unit assembly. If not, it's on the joint duct that connects to the blower unit. It has a 4 wire plug connector. Unplug and measure the resistance (on the blower resistor, not the plug) on the pins that the following wires of the plug connector were connected to: black/white to black/blue should be 0.31 ohms, black/white to black/red should be 0.87 ohms, black/white to black/green should be 1.83 ohms. Here's a pic of it removed (upper right): http://www.dsmtuners.com/forums/attachment.php?attachmentid=23143&d=1074560973.

For testing blower switch, unplug connector and check continuity on the switch (not the connector) from pin 5 (had black wire on it) to pin 3 (black/green) for Lo speed, then from pin 5 to pin 6 (black/red) for ML, then from pin 5 to pin 2 (black/blue) for MH, then from pin 5 to pin 7 (black/yellow) for Hi.

 

[jabinya]

That explains my problem, When I removed the AC evaporator, I thought that the resistor was a sensor for the AC and threw it out. Guess I was wrong!

Thanks for the helpful info!