Air ride adjust not holding ?

[Kummer]

Hello all, been awhile. I will be brief.... Had service air suspension code forever, had it read as CO626 LR position circuit Perf. Any ideas on how to repair ?

Also starting last year truck would lower in very cold weather ( I live in Canada). Once truck is started returns to normal and works fine.

Starting a few months ago, air ride adjust will raise truck but will not maintain it. Truck lowers itself to normal then tries again until I switch it off.

Any suggestions would be greatly appreciated.. Thanks in advance.....

Truck has 170K on it, I know I should convert to coils but love the air suspension, and why buy a Hummer if you cant afford to fix it LOL