Time to figure out what the root cause is.
While you're at it, make sure the vacuum-operated coolant crossover valve, and its associated solenoid-actuated vacuum valve, are functional. I think they're present on the Tahoe; I know they're on the Suburban.
Their proper operation will aid the AC system's operation.
If you have them...
- you'll find the vacuum valve mounted on the firewall, on the passenger's side (with some vacuum hoses and electrical wiring attached), and
- you'll find the coolant crossover valve mounted in a nest of heater hoses affixed to the passenger's side wheelwell, connected by a vacuum hose to the vacuum valve mentioned above
There was quite a bit of discussion about this coolant crossover valve / vacuum valve pair, and how to test / fix them, in this recent thread starting at this post and thereafter:
Heater issue?
They had different factory temps. I'm just curious what temp your running.
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