2002 Chevrolet Malibu Transmission Codes and Blower Speed Problem

Picture of blower resistor assembly

I had my 2002 Chevrolet Malibu serviced at non-Gm transmission shop which scanned the computer for codes. They found P0741 & P0730 which are TCC clutch related. I had them test drive the car to make sure it was not an intermittent problem which could be repaired other than the recommended re-flash of the PCM their service department suggested. They said the transmission wasn’t going into overdrive, so they flashed the computer. We noticed that the RPM’s went down and the overdrive gear seemed to be OK.

My wife is the main driver of our Malibu and she says that the heater vents are blowing cooler and the fan is running slower since they flashed this computer. Could them flashing the PCM effect what is going on now with the fan speeds and heater vent problem? We took a trip and I drove it and she is right. It now is cooler and the fan does not run as fast. The check engine light is going on and off.

I have read some forums and it seems that these 3100 motors have the thermostat stick or leak external and sometimes internally. What is my next direction to fix this?  Other than taking it back to the transmission shop. They do not work on engines. I will call them but they are limited to fix the other things. Any suggestions are welcome, thanks you.

I am thinking that maybe a pressure check of the coolant system and radiator cap is the next step . But i sure would like some of you current Gm guys to direct me. Its been 15 years since i was in the field in a Gm shop. We had more room to work under the hood then Ha Ha! For the life of me i sure wonder why the fan and heat would change? any ideas? Thanks again going to bed Ill check tomorrow Guys BYE.

Answer- Re-flashing the PCM would have nothing to do with the fan not blowing as fast, or the temperature. Yes, check to make sure the coolant level is full. Get the codes scanned, you may find a P0128. Caused by a bad thermostat or low coolant. If one or a few of the fan speeds don’t work, most likely a blower resistor.Picture of blower resistor assembly

If replacing the blower resistor, make sure you check the harness connector. Had seen a few times where the connectors had a problem, and the new resistor quit a few weeks later. You would see burned marks inside the terminals. If not to dad, you can repair this by tightening up the terminals and adding a little dielectric grease. If real black and burned, must replace the connector. It comes with wires installed, so just splice them into the dash wires.

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