Yukon heater blows cold checking options before buying Door blend actuator

[TWITCH101]

Like the title says, my Kon blows cold air when the engine is warm. now the thing about this is that the rear blows hot. So my best guess is that its my Blend Door Actuator but I'm asking questions first before I spend 50 bucks on a new one and it doesnt fix the problem....now I've read where flushing the heater core with a cleaner and water will fix it but I'm not sure if thats the problem since the heat in the rear works great. any input is great....


and if this helps I think the air blows lukewarm as the truck warms up but seems to cool off once the engine is hot. I don't know if this is just me thinking its warm because I'm inside the Yukon and away from the outside cold or if I'm really noticing a difference???

 

[TWITCH101]

anyone???at least give me a way to check things out...lol

 

[Rivieraracing]

Does the coolant temp ever fluctuate? Does it run cooler than normal when warmed up? I've had a thermostat get stuck open in my yukon before, lost all heat when the temp dropped!
Also, do you get any heat in the front when you are cruising as opposed to idling? If so, I'd say a heater core flushing might be needed!! If not, I'd be leaning towards the blend door since it's a common problem for alot of trucks on here!
Just throwing out some ideas for you, hopefully you will get a few others to chime in and help you out! Good luck!

 

[chauncey0337]

I would try flushing the heater core first because this process is virtually free.

 

[TWITCH101]

^^^thanks guys.....I think I'll give the heater core flush a try first and see what happens since that will only cost me fluid...lol....but to answer your question my temp doesnt seem to fluctuate while driving that I'm aware of....by when the temp dropped you mean the temp outside or the engine temp?

 

[Rivieraracing]

I meant engine temp!!

 

[TWITCH101]

^^ok...yea my engine temp doesnt really drop much if any....where is the thermostat? I might just check it anyway.

 

[Rivieraracing]

As for your problem, I did some research last night. Since the rear air blows hot when the front doesn't, I'd say your problem has nothing to do with a bad thermostat. The rear air has it's own heater core and since it is getting hot coolant to work, I'm guessing either a plugged front heater core or a blend door problem!! I'd start with a flush on the front heater core and see if that solves it like mentioned, at least that's a pretty cheap/free try at a fix!

 

[TWITCH101]

thanks man...had no idea there were two separate heater cores....That will definitely be my first attempt...I'll post up later and see if that fixed the problem.

 

[Rivieraracing]

Yeah, didn't know about the 2 either until just the other day!! Was gonna flush out the rear heater core but couldn't figure out how to unhook the quick clips holding the hoses on to the t connectors with out breaking them!! Gonna try again tomorrow and see if I have more luck!! Good luck with it all, and be sure to report back with your findings!!