How much free on in 2002 tahoe with rear air?

Not sure there is one. You have height sensors at each rear wheel and a compressor which often fails once a leak occurs cause it runs too much.

There are two heater cores

if this is a factory system, should have this info on the under hood decal

Hi
It holds 3.0 pounds when completely evacuated. Be sure to use R134a refrigerant with oil added, it is needed in the system for lubrication.

Please vote if this helped! Thanks, Mike

No just one compressor for front and rear system. what problem are you having?

I have heard some complaints on this but if you are the owner of any vehicle with air ride you know it can be costly to fix. You can fix your whole air ride system and save some money if you go to Strutmasters.com and get one of their non air conversion kits. No more leaky lines or bags this takes care of it all!

either the refridgerent charge is low OR the expansion valve for the rear a/c is bad. I would evacuate the system and recharge it with the right amount FIRST before trying to diagnose another problem. should be a decal under the hood for correct amount of 134a

sounds low on refridgerant

the system could still be low on freon even though front works

check fuses & power to blower fan motor,plug connections.then apply 12 volts to blower fan motor if it dont turn its bad