he blower motor cuts off at the max (5) setting?

Try checking the 40 amp fuse at the under hood fuse panel, here is the fuse location and a guide to help check it.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Here is the blower motor wiring diagrams so you can see how the system works. Check out the diagrams (Below). Please let us know what happens.

[quote:bcdf29cd0d="rasmataz"]Try swapping the blower motor relay don't work get the HVAC control module tested.[/quote:bcdf29cd0d]

By HVAC control module do you mean the actual unit that you can select speeds? The manual says that the blower motor relay is on the blower motor housing; can't find it. Help!

[quote:4ff7aed8e7="ecuello"]Heater problem
2005 Chevy Trailblazer 6 cyl Four Wheel Drive Automatic 64000 miles

I recently replaced the blower motor resistor and the resistor connecter due to the blower not working at all. Now the blower motor cuts off at the max (5) setting. I back probed the blower motor connection and I have voltage and it switches all the way up to 4. As soon as I set it to 5, the voltage drops and the blower motor cuts out. I also replaced the heater/ac control module thinking that was the only possible solution but it still cuts out. Both Contol modules (old one & new one)cut out on the max setting. I have also tried 3 different resistors and still have the same problem. Any direction given will be greatly appreciated.[/quote:4ff7aed8e7]

By HVAC control module do you mean the actual unit that you can select speeds? The manual says that the blower motor relay is on the blower motor housing; can't find it. Help!

Blower Motor Resistor Assembly Below right side of dash, near blower motor-sorry no pic's

[quote:a91c94c365="ecuello"][quote:a91c94c365="ecuello"]Heater problem
2005 Chevy Trailblazer 6 cyl Four Wheel Drive Automatic 64000 miles

I recently replaced the blower motor resistor and the resistor connecter due to the blower not working at all. Now the blower motor cuts off at the max (5) setting. I back probed the blower motor connection and I have voltage and it switches all the way up to 4. As soon as I set it to 5, the voltage drops and the blower motor cuts out. I also replaced the heater/ac control module thinking that was the only possible solution but it still cuts out. Both Contol modules (old one & new one)cut out on the max setting. I have also tried 3 different resistors and still have the same problem. Any direction given will be greatly appreciated.[/quote:a91c94c365]

By HVAC control module do you mean the actual unit that you can select speeds? The manual says that the blower motor relay is on the blower motor housing; can't find it. Help!

Already replaced blower motor resistor three different times thinking that they were defective.

Already replaced blower motor resistor three different times thinking that they were defective. Can anybody tell me where to locate the blower motor relay?

Try this: so much of auto references misdirections Check in the underhood fuse block -see below Itme NO.1 for location of relay

replaced relay; checked all fuses, blower motor still cuts out when max speed is selected.

Is there a procedure for recalibrating the HVAC control module?

What other trouble shooting can I do?

Did you check the wiring from the diagrams above? You must have a broken wire.