2000 Sierra... I'm ffffreezing

Heater is taking a very long time and only blows lukewarm. Coolant temp is around 200f ambient is in the twenties. Is my problem with the control head or something else? In addition speed no. 1 of the fan does not work the best I can do is 3,4 and 5.
Thanks

Could be that the heater crtl valve is not opening all of the way or your heater core is pluging up. See if both heater hoses are about the same temp, carefull they can be very hot. If the outlet hose is a lot colder than the inlet hose then the ctrl valve is not opening all the way or the core is pluging. If it is the core pluging then you will either have to replace it or have it back flushed. Most heater ctrl valves are vacumme operated and you should be able to move the lever by hand, if it is stiff to move then the valve could be gumed up. Also (when cold) pull the radiator cap to see if you are getting good flow.

Could be that the heater crtl valve is not opening all of the way or your heater core is pluging up. See if both heater hoses are about the same temp, carefull they can be very hot. If the outlet hose is a lot colder than the inlet hose then the ctrl valve is not opening all the way or the core is pluging. If it is the core pluging then you will either have to replace it or have it back flushed. Most heater ctrl valves are vacumme operated and you should be able to move the lever by hand, if it is stiff to move then the valve could be gumed up. Also (when cold) pull the radiator cap to see if you are getting good flow.

No heater control valves any more. Not sure when the last year was but it has been a while (my 90 K1500 does not have one).

The amount of heat is controlled by air flow thru the heater core.

Checking the hoses is a good first step. If they are both hot, then it could be an actuator or the blocked air flow thru the heater core.

//2000CAYukon