2000 Tahoe, No heat

[xwoodx]

Picked up a 2000 tahoe a month ago and it seems the heat is not working. It worked the night I bought it, not the next night. Since then it either doesn't work at all (usually) blows warm at best (sometimes) or works fine (rarely). The hottest it will blow out the dash is as hot as the rear heat will blow, but I thought the rear heat had a separate heater core....? It seems the issue is universal between the front and back because when it doesn't work at all on the dash, the rear heat is the same, no heat.

I found the cabin filter was extremely plugged so I replaced that. Also, is I grab the heater core lines under the hood one is very hot and the other is just hot... So it seems the core may be working fine.

 

[choloBigHead]

I have the same issue. I just bought a used Tahoe and am have a hard time with the heat. I do occasionally have heat, but most of the time I don't. I hope to get some useful info from other members

 

[Bomber495]

I'm having the same problem on my 03. Have had it since new and all the sudden no heat. Coolant level was low so I flushed dexcool out, changed thermostat, changed water pump gaskets and seals, and changed both belts and fuel filter while I was working on it. I have not gotten the water pump back on yet or have any coolant in the system but I'm switching to American green coolant away from the deathcool. I will let you know how my heat works after everything is back together tomorrow since I had to stop due to rain today.

 

[xwoodx]

I switched the waterpump and thermostat out a few weeks ago due to a very loud waterpump bearing and it did not fix the issue. It had the problem before and after the waterpump. Coolant level is normal.

 

[rockenthebowtie]

Check the HVAC temp door actuator that is located un the dash you will need to remove the long black under dash cover to gain access it once removed it will be located to the right center its a black triangular plastic box with a 4 to 5 wire connector... it has two 7/32 hex screws holding it in place.. once off rotate the temperature door with your fingers you should be able to tell the difference between the temperature change in the vents.. if it blows hot and stays hot once rotated to the heater position you may have a bad temperature door actuator thats the one you removed.. as for the rear make sure you have no air pockets but it may also have a defective actuator... you my want to flush some water thru the heater hoses first right there at the fire wall where the heater hoses come out or at the water pump itself you know the ones coming off the side of the water pump remove the smaller of the two hoses and attach the garden hose to the heater hose and run some water thru it see if that helps