No heat at slow speeds

[Stockfornow]

The heater blows cold when the car is idling/not on the highway. Temp gauge reads 210. As soon as I get up to highway speeds (65-70) I have hot heat coming through the vents. As I slow down, it gets colder.

Thoughts?

 

[Thumper8302]

first few things i would check would be ur coolant level, thermostat, water pump, and just for ***** and giggles see if ur front pass floor board is wet ( possible heater core )... i remember in my 90 burban i had a similar issue except i would get heat when the motor was revved over 1000 rpms.... had a small crack in my heater core... replaced that and all was good.... but i would check those things first... and also see if ur blend doors are opening and closing like they should.... best of luck man

 

[06HOE]

I am having the exact same problem. How did you resolve the issue?

 

[Rivieraracing]

If it's doing this only at an idle and it's not overheating, I'd say your coolant level is low or your heater core is partially plugged! Are both hoses going to and from your heater core in the firewall both hot to the touch when the truck is fully warmed up? You say that your coolant temp is at 210 at an idle, what does it do when you get up to highway speeds and the heat stops coming out of the vents? If it drops alot, your thermostat might be stuck open and not closing when it needs to (happened to me with a 3 month old thermostat, changed it out and problem gone).

 

[swtz71]

your thermostat may be stuck open.. that would allow the coolant to flow and when you are at a higher rpm your coolant is flowing faster not allowing it to cool as quick..
But that could be totally wrong as vehicles are so unpredictable..

 

[jhellwig]

Your coolant level is low. The reservoir is full of junk making you low coolant indicator not work. You probably have a intake gasket or a head gasket leaking that is causing all of this.

Typical problems. Easily fixed.

I dumped my hoe. It was doing the same thing and the wife didn't want me to bother fixing it.