Stuck thermostat; heating blowing cold air?

[whitestingray81]

I used the heater for the first time today in my '07 Avalanche (5.3L Flex fuel). It only blew cold air. After letting it sit idling on my driveway for 20 or so minutes, with the heat all the way up to 90 degrees and the fan up all the way, I can feel warm air, but not SCOLDING hot air, like I expect.

I felt the lower radiator hose, and it is cool to the touch. Could the thermostat be partially stuck open? My engine temp is a steady 210 degrees, so it doesn't show the engine running too cool, or overheating for that matter.

Oh, also, when I turn the heat on and press the "AUTO" button, it turns the A/C on and only blows on my feet!? Possible controller problem? Thanks in advance for the help. Oh, I should mention that I have the 2-zone (driver/passenger) electronic HVAC, whatever the model is called....

 

[jdpber]

The blend door motor actuator is stuck or busted. This is a common problem. I had to replace mine a year ago. It is under the dash at the trans tunnel. I believe it was a $40 part and 15 min fix. Simple hand tools.

 

[whitestingray81]

Wouldn't the blend door mean either the passenger or the driver had hot air, but the other didn't? I'm not getting any hot air at all, unless I crank it and let it sit; then it gets just warm. But I hope your fix is right; just need confirmation.

 

[ccapehartusarmyINF.(ret)]

the problem i had on my ford ranger was a valve under the hood that allowed coolant into the heater core when you turned up the heat i think it was like 40 bucks to replace i realize its a completely different vehicle but it mite point you in the right direction

 

[whitestingray81]

Okay, did some more testing tonight.

When driving, or idling with my foot on the throttle (to around 2000rpm), I get HOT air, but when engine is at idle in park or at a stoplight, it cools down immediately. T-stat? Clogged heater core? The blend door? Thanks!

---------- Post added at 09:26 PM ---------- Previous post was at 08:12 PM ----------

Fixed!

I went out to the garage to see if I could locate the heater core hoses as I was planning to flush them out tomorrow. Well, one of the hoses was crimped shut by the plastic engine cover. I freed it and IMMEDIATELY got scolding hot air. So there we go!

 

[jdpber]

Wouldn't the blend door mean either the passenger or the driver had hot air, but the other didn't? I'm not getting any hot air at all, unless I crank it and let it sit; then it gets just warm. But I hope your fix is right; just need confirmation.

Their are 2. One splits left to right in the cab and one is at firewall and adjust the air into the cab.