Yukon heater blows cold checking options before buying Door blend actuator

[TWITCH101]

I'll for sure be back later to let you guys know what happens...gonna try and get around to it today if other projects dont get in the way.

---------- Post added at 08:28 AM ---------- Previous post was at 08:21 AM ----------

So I'm guessing you can get to the heater core connection from under the hood right?

 

[Rivieraracing]

I'll for sure be back later to let you guys know what happens...gonna try and get around to it today if other projects dont get in the way.

---------- Post added at 08:28 AM ---------- Previous post was at 08:21 AM ----------

So I'm guessing you can get to the heater core connection from under the hood right?

Yeah, if you wanna do the front core separate from the rear, you will need to undo the quick clamps at the T connectors at the firewall where the hoses go in for the front core. Or you could just follow both hoses from the firewall to where they tap into at the front of the motor(I know one goes to the waterpump, can't remember exactly where the other goes to) and flush it that way. It will flush your front core just fine, and since you are needing to do that anyways that would work, it just doesn't flush the rear one very well that way!!

 

[TWITCH101]

just now getting around to working on this thing....which T fitting is the one for the front core??? there are two side by side...is it the one closest or farthest from the intake manifold?

 

[chauncey0337]

If you're talking about the two hoses on passenger side firewall, they both go into the front heater core. One goes in, one goes out.

 

[TWITCH101]

Ok I understand now...so the two lines that come from those two go to the rear heater core?

---------- Post added at 02:59 PM ---------- Previous post was at 01:42 PM ----------

Just finished the first flush...got a little bit of junk out of the line but didn't seem to be a while lot of mess, just some rusty looking water......bouht some radiator flush and poured it directly into the core and then hooked everything back up and ran the motor with the heater on high until it was hot...the front heater blew scorching hot air and never slacked off.....letting the motor cool and doing another flush then. And going to try out the heater tonight when it gets freezing and see if that makes a difference since its 60 degrees outside right now. I'll report what I find when I get back from the drive tonight.

 

[chauncey0337]

Ok I understand now...so the two lines that come from those two go to the rear heater core?

---------- Post added at 02:59 PM ---------- Previous post was at 01:42 PM ----------

Just finished the first flush...got a little bit of junk out of the line but didn't seem to be a while lot of mess, just some rusty looking water......bouht some radiator flush and poured it directly into the core and then hooked everything back up and ran the motor with the heater on high until it was hot...the front heater blew scorching hot air and never slacked off.....letting the motor cool and doing another flush then. And going to try out the heater tonight when it gets freezing and see if that makes a difference since its 60 degrees outside right now. I'll report what I find when I get back from the drive tonight.

Yes, it looks like they Y off to the rear core. Good luck. Let us know if the flushing works.

 

[TWITCH101]

ok guys.....did my flush a few days ago and everything seems to be going good so far....heater blows hot....only notable thing is that the heater will blow hot as the truck is warming up then gets lukewarm once the engine temp gets up to about 170-180 degrees...then once the truck reaches its 195-200 degree operating temp the heater starts blowing hot again. My guess is that the thermostat opens up and allows the rest of the coolant to flow into the engine/heater core and it cools down until all the fluid is hot. not sure but thats my theory.

I'll report back later if I have any issues down the road.

 

[M3PO]

My guess is that the thermostat opens up and allows the rest of the coolant to flow into the engine/heater core and it cools down until all the fluid is hot. not sure but thats my theory.

Yes or you have a flaky thermostat. Keep an eye on your temps. I haven't driven my truck since yesterday, I'll try to remember to see if mine does what you are talking about.
Also, not trying to be funny- do you have climate control? or do you have the manual temp selector?

 

[Rivieraracing]

ok guys.....did my flush a few days ago and everything seems to be going good so far....heater blows hot....only notable thing is that the heater will blow hot as the truck is warming up then gets lukewarm once the engine temp gets up to about 170-180 degrees...then once the truck reaches its 195-200 degree operating temp the heater starts blowing hot again. My guess is that the thermostat opens up and allows the rest of the coolant to flow into the engine/heater core and it cools down until all the fluid is hot. not sure but thats my theory.

I'll report back later if I have any issues down the road.

Is all this warming up talk when you are actively driving your truck or is this all at idle?

 

[TWITCH101]

Yes or you have a flaky thermostat. Keep an eye on your temps. I haven't driven my truck since yesterday, I'll try to remember to see if mine does what you are talking about.
Also, not trying to be funny- do you have climate control? or do you have the manual temp selector?

Yes I have climate control but I keep it set at the hottest setting instead of a set temp like 76 degrees for example..

---------- Post added at 03:02 PM ---------- Previous post was at 02:59 PM ----------

Is all this warming up talk when you are actively driving your truck or is this all at idle?

yes this is while actively driving....I can physically feel a difference when it blows lukewarm and I look down at the temp gauge immediately and it is consistently around 170-180 when it happens......doesn't last long at all though.....maybe 45 seconds....just until the temp gets hot.....just thought I would throw that info out there....but it hasn't been too cold until today it got down to 33 so I'll test it tonight when it drops down really low.