Low on coolant.
Bad thermostat.
Plugged heater core.
Temp blend door inop.
thermostat stuck open or air in cooling system
What temp. thermostat did you put in? Try a higher temp. one. or check to see if heater core is clogged
it sounds like your choke is not operating properly.
If the heater in your 1999 Suburban with a 6.5L engine isn't getting warm or hot, it could be due to a few reasons. First, check the coolant level; low coolant can prevent proper heating. Additionally, a malfunctioning thermostat may not allow coolant to flow into the heater core, and a clogged heater core can restrict hot air from circulating. Lastly, ensure the blower motor is functioning correctly to distribute warm air.
With engine warmed up and running, open the hood, locate both heater hoses, feel each heater hose with your hand. If both hoses are equally hot, I would suspect you have a temp blend door problem. Replace the temp blend door actuator. If one hose is hot and the other is only warm or cool, I would suspect you have a plugged heater core, Try flushing it.
you have a bad heater core
that has a lot to do with.if your heater core is pluged up you wont get any heat out of it.
Piston heater element open.
it won't start because it is not warmed up if you know what i mean!! lol!13 rules 4-ever
some place very warm so that they wont become extinct animals
Yes they are! spesh the ones with the fur linning!!
Low coolant level? Cooling system airbound? Bad thermostat? Water pump not circulating coolant? Heater control cable not working?