Opposite from the other posts I have found on here,
Our 2007 GC SXT has front blower on all speeds except high.

So my assumption is that it is not the Resistor.

What else could it be?

Some packages have a plain type resistor, others have a little module type resistor. Usually if you have Auto climate control. They tend to go bonkers in any speed position.

Check the resistor connector and see if it is overheated or starting to melt

Okay I looked at the Connector(s) no signs of over heating.
So I removed the Resistor, see attached photo.

From my searching on-line this resistor doesn't look like the OEM ones I have seen so it has been replaced already. I am the second owner of the van.

Also, I noticed a small chunk of the green coating near the blue resistor to be missing.

So I plugged it all back together and it still does not run on high, only the three other settings.

Note, it does not have Automatic Climate Control.

So, what do you think should I buy another resistor and give it a try?

it is most likely your resistor.
it is also possible the Switch is broke.
How many speed selection do you have? 0 - 4, or 0-5?

It has the 0-4 speed selection.

So would you sudgest to change the resitor first?

The only way to have all speeds but high is to have a connection issue, an open wire to the switch or a bad switch. If the resistor were bad, you would have no speeds. There is a wiring diagram for this system in the DIY section

Unless these wiring diagrams are lying to us, if you measure between pins #1 and #2 on the resistor block (6 pin connection) and get any resistance other than infinite the resistor block is good. This just proves Tizzy1s statement. You're measuring resistance through a resistor in the block for the high speed position. If it's open then you should see infinite resistance and none of the speeds would work. The voltage for each speed position runs through the high speed position resistor.

To check the high speed switch position disconnect connector C2 on the A/C heater panel and check resistance from pins #2 to pin #4. Should see no resistance with the switch at high.

Then it is most likely the switch.
well, If you have Multi-meter and knows how to use it, definitely do the tests suggested above. Other wise, we are just guessing.
The control switch is like $100?
or just leave it alone and not fix it.

Okay I got the wiring diagram and a do have a multimeter.

So I will test the thing out this weekend when I have some time.

Assuming that you need to remove the Trim around the AC/Heater Control to get at the back of the switch.

Saw a Video on Youtube of guy doing that, going to watch it.

Question, can you replace just the switch all I have found is complete module and the cost was $200 to $300.

If that is the case I will just leave it alone.

Hoping maybe it is the wire connection.