Low speed fan is not coming on with AC. Not the resistor.
 

I just purchased a 2006 MCS and noticed that the ac only comes out cold on the highway or apparently when the hi speed fan comes on. I thought it was the resistor issue. I bought the resistor and everything. Today i got a hunch and decided to run a line right to the battery from each wire (hi/low) and both speeds work. Ive checked all of the fuses and none of those are bad. Ive also switched the relays under the hood around and still no go. Does anyone have any idea what the issue might be or where i should look?

Edit. I checked power at the plug with a simple test light and got no power. I also felt if the relay clicked and it didn't. If it does happen to be the relay could anyone point me to where i can buy one?

Had the exact same problem as you. I snipped the high speed fan wire and the low would work. Eventually found the relay in engine compartment was not fully clicking. Opened it up and there was some dust stuck between the contact. Cleaned it out and all went back to normal.

Regarding buying a new relay no idea in the states where to pick one from, but a simple google search with the voltage will bring up a few suppliers.

Update time. I checked all of the relays and they all click when 12 volts are applied. Te relays are also getting 12v at the fuse box. Is it possible I'm stupid and the ac isn't kicking on because it's too cold out? It's in the high 50's at the moment.

Took it to the dealer. It ended up being low freon and a leaking hose. They fixed it and now the ac works perfect.