Should be easy. Disconnect wires coming in to doors. This may involve taking side panels off. Than unscrew security link and after unscrew doors from hinges or doors with hinges from the frame your doors will freely come out
Either stuck blend door or a bad blend door actuator motor. It's located under the dash. Remove the actuator and move the door by hand to see if it's binding. If it's free, then the problem is with the actuator or linkage.
That is the fuel composition sensor ! Does your Suburban have duel fuel tanks or single tank ? What engine is in yours ? The fuel pressure regulator in located on the fuel injector rail on top of the engine . I would say the fuel pump was bad , just from personal expeirence . But if you don't know how to test the electrical circuit an check for fuel pressure with the correct tools , i suggest you take it to your chevy dealer . Is it a flex fuel vehicle ?
GM Fuel Pump Relay Testing
Remarkable that you need to do this, but perhaps you have high miles. Changing the chain is easy, but so is getting it wrong. Buy a cheap shop manual for full information and torque specs.
You have 4 relays that control the doors on your front vents. Open the glove box and depress the side to expos? the area behind it. There are 4 square damper controls there place the front A/C to vent and tap on them sometimes they get stuck mid cycle. If you believe they are bad, go to the junk yard and pull replacements. These tend to be expensive at the dealer. If this works you know where the problem lies and you can then buy new ones at the dealer. Good luck hope this helps.
