I have a 2004 Suburban Z71 with automatic climate controls and rear heat/AC. I go to turn on the A/C and it doesn’t blow cold in the front, but it does in the back. I had it recharged twice and it worked for the first month each time, but then it blows cold only in the back again. Is the problem a blend door actuator stuck open? Or is it something else?

 

If adding R134A makes the front A/C work, sounds like you have a refrigerant leak to me, but I am not that familiar with rear A/C systems, just the front.

 

Above is correct, as adding R134a makes it cool fine for a while. Leak can be anywhere, even in the lines going to rear evaporator box or hidden there. I suggest getting a real AC shop to add some UV dye and then check for leaks with a UV lamp and goggles. Also, it is possible that your 2004 has UV dye in it already. But front and rear evaporators are hidden and typically require electronic sniffer testing as well. Don't overlook that bad service valve caps can be a leak point, as caps are extremely important parts of the system !!!

Whatever you do: do NOT add any sealer or refrigerant containing sealer - EVER !!!

 

04Z71Sub: Welcome to the forum.

Not sure how it can be a refrigerant problem since both evaporators operate off of the same system. I don't know if there's any valving involved between switching front to back in the refrigerant system. When you have the system on cool, are you getting any air out of the front vents at all? And if it's warm, then I would suspect the blend door.

 

Front system has orifice tube and rear has expansion valve.

Not an uncommon issue. A shop can measure the weight of R134a in the system, which is tons better than guessing by system pressures.

 

Yes it is, but can run the bills up fast. I am going to have to study these rear A/C systems, even though I've never worked on one. The expansion valve in the rear
makes sense to me now. Used to be most A/C systems used them but the orifice tube is cheaper, so I suppose that is why many vehicle manufacturers use them.

 

Maybe something here will help https://www.thetruckstop.us/forum/th...lve-txv.23287/