Heater Relay??

I read a couple of posts where people seem to have the same issue as me but on different years. I have a 2002 Astro AWD and my heater blower fan only works on the 2 highest settings. I did like another person was told, I followed the purple wire from the blower motor and ended up on what looks like a relay board. Part number on it says 12135105. I was hoping that changing the relay would solve my problem, but the whole thing looks like one assembly. The board itself seems to have a couple of spots where the varnish is peeling off, but it does not seem to have any burnt spots or broken leads.
Anyone have any ideas for an inexpensive fix. I know the last time I change that board on my previous 1997, it was a couple of hundred bucks.
Thanks!

There is a blower resistor array in the ductwork near the fan. Check the electrical connector at the resistor array. The newer resistors are also suspect. They are no longer a wirewound type, but are merely foil traces on a circuit card. A little contamination on the circuit card is all that's necessary to insulate it from the passing cooling air and shorten its life.

Since the blower operated on more than just the highest speed, it is not likely a problem with the blower high speed relay, and is likely either the resistor or switch.

I'm going through a similar problem with my 94. It seams it's usually either the relay, the switch or the resistor module. You can read through my posts and see that I was able to track it down with help from Old Master. I used a multi-meter to check for voltage and determined there was no voltage getting past resistor module. I would suggest the same thing.

First I checked out the switch in the dash by removing it, taking off the wiring harness and checking it for continuity with the multimeter. If you get continuity in all switch positions then it is probably not the problem. Next put the multimeter in DC voltage metering mode, put the key in the run position (don't have to start the engine) and set the mode switch to heater. Check for voltage after the resistor module (I did it at that relay module wiring harness with the relay module removed) and determine weather or not the resistor module is passing current. You'll have to check it on all blower settings. I'm not sure what the wire colors are on your 02' but on mine the dark blue wire had no voltage present on any of the settings and it mostly likely is causing the problem. You should find voltage on all the wires at various blower switch settings. Old Master maybe can help you out there. If you don't, it's "upstream" from there. I ordered a new one for $25 bucks. Watch my posts and I'll report if it did the trick. I'm pretty confident it will.


Somebody double check me and make sure I'm not giving bad advice please.

I think the 2002 is a bit different. I followed the purple wire as per your thread and it looks like the resistor and the relay are all in one??? I could be wrong, since I checked all this in -10 celsius plus windchill. Man, I hate winter!

Yes, the blower and relay are all in one on your 2002--this started in 1996 model vans- through the end of production- that relay/resistor board is only about $40-$60 at places like NAPA. I have replaced several- there is about a 98% probabilty that changing this board will fix your problem....

Got the new resistor relay at Part Source for $41.93. What a mess to install it, they are nice enough to give you a template to cut the hole it goes into, because someone thought it would be funny to change the shape of the new and improved resistor relay. So after cutting and saying a couple of unmentionable words, I got the new one in place and it solved the problem.
Thanks to all!

Nice!

Sorry I was little help. What can you do? I'm a long haired blues musician, not a mechanic unfortunatly.