1999 tahoe-NO HEAT

[rems99]

whats up guys and gals? Im new to this forum so please be patient if im doing something incorrectly. I have a 1999 Tahoe Lt four door 4x4 with 5.7 litre v8. My heat has stopped working completely. Both hoses going in and coming out of heater core are hot when at normal operating temperature. Thermostat was replaced about one year ago. Coolant level is normal. Air flow changes from defrost to vents to floor like normal, just no heat. Any suggestions on what to check would be greatly appreciated!

 

[IronMan4Real]

Disconnect vacuum box prior to going in heater core. Get bypass valve at local hardware store. Flush out with CLR. Let sit for 10. Rinse with water and fill with pre mix dex cool. At same time replace t stat for argument sake. 30 min work tops.

 

[rems99]

Thanks ironman4real. Will do that. Is there a possibility of blend door actuator being bad?

 

[IronMan4Real]

I removed mine. I did the t stat first because time and mileage. Did not fix issue but it's done. No need to worry about it.
The CLR did trick for me. I have a 99 and had no heat. Same issues

 

[rems99]

thanks for your response. I will do what you recommended.

 

[IronMan4Real]

No problem! No guarantee but I had same issue. And it blasts head and being -12 Celsius here. Kinda need it

 

[lesterl]

He has hot hoses going in and out of core, suspect blend door actuator behind glove box.....

 

[IronMan4Real]

I had the exact same issue. Well the exhaust hose coming out was hot but not as hot going in. CLR is about $8 here and some antifreeze. Cant hurt to try. T stat about $9
So 30 min and $20.
Mine may have been plugged forever as it was a florida vehicle and now in Canada It needed heat for first time.
Very good chance you are right Lester1. I just suggested it because I had exact same issue and what I did repaired it.

 

[lesterl]

I have had the plugged core before, found out the hard way to flush with a garden hose not an air compressor.... Antifreeze dont taste half bad.....

 

[IronMan4Real]

10 Min with CLR works amazing.

 

[IronMan4Real]

Wonder if that fixed his problem?