My A/C blows hot air. I could jiggle the hot/cold knob and the cold air would kick in but know that doesn't even work. I have had all components and freon checked. All check okay. Sometimes while driving the cold air blows intermittently. Any suggestions to check next?

vacuum controls stuck work the knob a bit and try to free it..

You have broken vent flap servos or just need calibration with Volvo diagnostic tool.

THE HEATER CONTROL CABLE, VALVE, OR SOLENOID IS STUCK OPEN......LETTING COOLANT INTO HEATER CORE AT ALL TIMES
FIND BAD COMPONENT-REPAIR

you need to go under the glove box and replace the blower resister

Just fixed this problem on my '06 Sentra. The AC lines were freezing cold so I figured the system was cooling with no problems but the cold air wasn't getting to the cabin for some reason. I put a snake camera in through the vent behind and to the left of the glove box(you have to remove all of the panels) and saw that the cable that gets pulled/released when you turn the hot/cold knob had broken off from the retaining clip. This caused the whole line to move when the knob turned meaning that the cable wasn't actually being pulled in when turning the knob to cold. I pulled the center dash and CD player out and the cable was right there so I secured it in place with a zip tie. Everything works like new now.

there should be a temperature door, but I don't know if there is a cable or if its electric. turn the temp knob, if it feels like it moves anything? I dont have a diagram here at home, but will monday/

You're on the right track. Look under the hood for a broken, cracked or dislodged vacuum hose. It's almost always the problem.

You can tinker with it, if you know how to get behind
the knob and look for the loose wires and re-solder it
in place.

new r134a air con gas does not lubricate seals unless working all the time therefore the gas leaks from around the joints probably needs a regas

You have a broken wire connection between the temperature control knob and the circuit board behind the center dash console. Vibration causes the failure and once the control knob gets loose the solder connection fails.

For someone that knows how to remove the dash unit and can re-solder a couple of new wires this fix should take no more than 1 hour. Make sure that you apply loctite to the heat control knob spindle nut when you re-assemble it.

The dealer quoted me 750 dollars to fix this issue and I found out that it's a common failure for this year. I fixed mine virtually for free but it took some tools and about an hour of my time.