GMC Repair: GMC JIMMY heater problem, gmc jimmy, vacuum line

Question
1999 GMC JIMMY,6 cylinder with air.
Heater blower is working but no hot air.
3 months ago I replaced the water pump due to overheat problem and all OK.
I chanmged thermostat last month due to "warm air" coming out of heater instead of hot. This worked.
Now, not even warm air coming out. It is actually kinda cool.
Antifreez level was a tad low so I topped it off. A/C working. Temp gauge says indicates temp at around 190 or so. Radiator can be touched by hand after JIMMY has run for 1/2 hour.
Any ideas?
Thanks for your help.


Answer
Does the engine EVER overheat at any time especially under heavy acceleration such as climbing a steep hill ?.

Are BOTH heater hoses HOT to the touch when the engine is at normal operating temperature ?.

Are you getting coolant flow TO and FROM the heater core ?.

Is the air flow coming out of the correct interior vnts when you select A/C-Heat-defrost ?.

What mechanical work or ANY kind of work has been performed on the vehicle recently ?. As most problems that occur after a recent repair was made can be traced back to the area of where the repair was made as a vacuum line may have been knocked loose or a wire connection came loose, Look around in the area where work was performed..


Let me know.


autohelp