2005 suburban z71 rear heat issues

[Special-Ed]

I had to go up north for a couple weeks and it looks like my rear heat is inop

Electrically and motor wise it's fine. But there is zero hot coolant going into the rear heater/ac box

I replaced the water pump and t-stat last spring(it was leaking coolant)

Either there is massive vapor lock at the rear heater core or there is no water flow... The hot pipe to the back is only warm right at the front wheel well

Or the casting on my new water pump is not right and the flow is wrong

Just looking for ideas before I grab another new water pump and T-stat

My question is is there a way to bleed air from the rear heater lines or what?
5.3L z vin. Flex fuel motor

Thanks in advance

Ed

[Special-Ed]

Problem solved.

Replaced water pump t-stAt and flushed out the heater cores reverse and forward

Replaced all coolant good to -30f

Rear heat now works.

My hunch is a combination bad t-stat poorly cast water pump.
No junk in coolant when I reversed flushed

Hope this helps somebody

Water pump and t-stat took about an hour to R&R
Flushing about an hour. Had to make some special tools included in that hour