So my 2000 Blazer project is almost done and ready to be sold. There are just two little quirks that I noticed once I got everything put back together after replacing the heater core. I'm not sure if it had these problems before I tore it all apart or if it was because I didn't put everything back together quite right.

The first problem is with the climate control. Everything works mostly right, but if you have it so that it's blowing on your face and then switch it to defrost, it wants to keep blowing on your face. However, if you switch it to cold and back to hot again, it will move to the defrost like you want it. I'm guessing it's a vacuum leak somewhere, but I don't know which connections I should check and was wondering if someone could point me in the right direction.

The second problem is with the speakers. The front speakers work fine, but I noticed that the rear speakers are not working. What connection(s) should I check? I also noticed that some of the lights on the head unit don't come on, like some of the ones that backlight the numbers for the radio presets. I'm not sure if that's related or not.

These are both pretty minor quirks in an otherwise good truck; if diagnosing and/or repairing either of these two issues is going to be too difficult or too expensive, I'll probably just leave them.

Thanks in advance for the help!