2005 Envoy HVAC problem

My max setting on my HVAC (level 5) does not work on my '05 Envoy. Speeds 1-4 work fine but on 5 it just turns off. Does anyone know what would cause this? Is it just a fuse? Any help with this would be appreciated.

First check the fuse and then the fan relay.

Most likely cause of this problem is a burned out resistor in your blower resistor. The blower resistor is underneath the right closeout panel in the passenger compartment, (below the glovebox) and is plugged directly into the blower motor with a two wire connector. You say that the fan speeds 1-4 operate normally, which tells me that the fuse (40 amp fuse#35 'BLOWER' at the underhood fuseblock, and 30 amp 'HVAC' fuse#44 in the fuseblock under your left second row seat) are NOT blown. If they were, no speeds would work. If you have a 12-volt test light, you can unplug the 7-wire connector from the resistor itself and test it. Connect the test clip to a good ground and test each fan speed while touching the corresponding wire on the resistor connector: Red wire, pin G should have constant power. orange wire, pin f shoud be speed #5, purple wire, pin c should be speed #4, light blue wire, pin d should be speed #3, tan wire, pin a should be speed #2, and yellow wire, pin b should be speed #1. The black wire is ground. Each wire should light up the test light when touched when the corresponding speed is selected on the fan switch.<If all of the speeds light up the corresponding wire at the connector, that means the resistor is getting all the right signals and has an internal fault and should be replaced.> If you find the connector won't unplug or is melted, GM has an updated connector as a fix and the resistor and connector should be replaced.

ENVOYXUV
I have had so many issues with my 2005 Envoy- I love the truck but am tired of paying the dealership for so many problems. When my ac/heater blower stopped working in the winter I was quoted 200.00 just to put it on the machine at the dealership so I parked it from winter 2007 until july of 2008. I did a google 7/8 and found your post. I printed it- went to the dealership and ordered the part-a/c blower heater module $123.00- and yes it works now after my husband replaced it..... Are you a mechanic- if so you are hired- thank you so much for the advice- 123.00 compared to a possible 500-600 charge..... awesome advice.

Teresa :)

forgot to mention- the dealership initially gave us a resistor for the 2005 Envoy- which looked nothing like the part in the glove box- my husband took it back and the dealership referred to the part as an ac heat blower module- however, we couldn't have figured it out without your advice... thanks again :)

This thread is dead at 1 year old, thanks for the kudos to the OP, but this will now be closed.