QuestionQUESTION: The blower motor on my 1999 Chrysler LHS will not come off High. It will not shut off at all. I get codes 1489 and 1490, low and high speed realy circuit fault. I can't see where that relay is located in my manual. Any ideas?
ANSWER: Hi Tim,
When you say the blower won't come off high or shut off at all, I assume that you are describing the blower in the cabin for the AC/heater. I assume it will shut off if you turn off the igntion key, correct? There is a conventional and and automatic temp control type of unit. One has a fan control by conventional resistor block, the other uses a solid state multi-voltage unit. Both of these devices are located in the air duct under the dash which is close to the blower motor. There is a wire harness from the blower motor to the unit in the duct so follow that to find it. Usually, the problem with a stuck on unit in the ATC situation is a failed ATC blower module, the one in the duct. In the case of the conventional unit the resistor block fails such that it will not operate at the lower speeds but only on high and you can turn it off. So if neither of those possibilities apply it could be the control panel itself that is faulty. But let me know which type of system you have before concluding it is not the module in the duct that is bad.
On the fault codes, do you notice that the fans behind the radiator aren't working? The power fuses for the fans are in the box under the hood, fuses B and E, but the codes say there is something wrong with the relay control circuits that feed current from those fuses to the motors. That control circuit is powered by fuse 21 in the fuse box behind the left end-cap of the dash, so check for that. The cirucits are simple activation of either relay via the PCM at pins 55 and 69 which when grounded will cause the high/low and the high only relay to close, respectively. So it has to be fuse 21 or the wires between that fuse and the felays located in the box under the hood. Those relays are the next to the most outboard in the back row, and the only relay in the front row of the box. When the ignition is in the run position, the inboard most pins of those relay should show 12v if fuse 21 is working. Otherwise the fuse is bad or the wire from the fuse (light green/black to the relays) is 'open'.
Roland
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QUESTION: It is an ATC. The fan speed control knob on the dash has a mini fan behind it, I assume to pull air from the cabin into a sensor. So, can you we assume it is the ATC blower module? You say that is in the duct? How accessable is that?
Thanks again, Tim
AnswerIt sounds like the ATC blower module is shorted closed. If you remove the pad on the lower edge of the dash on the right side you will have better access to the housing that holds the blower and the ducts. Just follow the wire from the blower motor housing to a socket at the duct, remove the plug, then 2 screws and the module will drop out of the duct.
Roland
