removing the heater core 2001 - 2500HD

[mdfinney1]

I am attempting to fix my heat problems on my 2001 Chevrolet 2500HD, if have narrowed it down to I need a new heater core. I have completely dismantled the dash to where I can see the top of the heater core. (probably should have come for help before going this far, but I figured this is how to get the heater core out.) Now I am at a loss I can see that it appears that it should come out the top, but I will have to bend the pipes that go through the firewall. Any suggestions or ideas on where to find out some better directions.

[73ChevelleSS]

The dash needs to come out.Heater/AC box unbolted from firewall.Good luck,take your time.Once the box is on the floor you can seperate the case halves and remove core.

[mdfinney1]

how do you disconnect the passenger side heater hose, I was able to get the driver side loose. It was simply a pressure hose clamp and pull the hose. The other is like a connection that cannot be removed. I can twist it but not remove it. Probably real easy when you know how.

[dr.gizmo]

There are two tabs that you depress and then you twist and pull to remove it.

[MrCritical]

We've had local independent shops bring these trucks in for heater core replacement-they've done it once and said, "never again".

[mdfinney1]

Ok, I am at a loss!! and extremely frustrated!!

I finally took the truck in to have the heater core replaced and the heater is still not working. Most of the time it is blowing cool air even with the AC off, and with the AC on it blows cold all the time, but occasionally with the AC off the heater will blow warm. I have checked the actuator that controls the cool/heat and it appears to be working correctly. It will turn the full 180 degrees when the dial on the dash is moved from cold to heat. With the actuator removed I can move the cool/heat door manually but it will only move about 20 to 25 degrees, not the full 180 degrees like the actuator does. I feel that this is my area of problem, but I have talked to the person that replaced the heater core and he stated that it should only move that much. He also showed me on another vehicle, a 2002 chevrolet suburban with the dual cool/heat control, and the door only moved about the same distance. We did not check the actuator to see how much it would move.

Side Note, when I have the dash removed to in the attempt to replace the heater core I observed all the other actuators working properly. Also I cut the old heater core apart and did not see any signs of it being clogged up or not working properly.

Is there anything else in the AC/Heater system that would control cool/heat?

[sonjaab]

If your heater core was bad you would see a coolant leak/smell and your windsheild would be fogging over. Quite the complicated repair requiring total dash disassembly and removing the entire interior heater/ac "suitcase" to get to the core for removal.

If no leaK/smell/window fogging and just no hot air I would look to the heater control door assembly being inoperative (not moving).
There is a reset procedure I have seen used in other GM truck forums that sometimes resets the temp door control and gets it working.
Check out www.gm-trucks.com/forums or www.fullsizechevy.com/forums
Do a search there and it will come up.

I will post the link if i come across it tonite!

EDIT: See next post.

[sonjaab]

As promised heres the heater/ac blend door (actuator) reset procedure:

troubleshoot that actuator first before you replace it, by:
1. DISCONNECTING THE NEG BATTERY POST FOR 5 MINUTES.
2. RECONNECT THE NEG BATTERY POST.
3. TURN THE KEY TO ON FOR 3 MINUTES
4. START THE ENGINE AND CHECK THE AIR TEMPERATURE/DOOR
OPERATION.

This will only take a few minutes to accomplish. It will reset the entire system clearing any faults that might cause the actuator to drive wrong. It MIGHT also save you some cash in parts that you don't need. The proceedure is same as in the orginal post item #2 but your doing it before the actuator replacement and your reseting more than the HVAC system by removing a fuse.

If that don't cure your problem heres the repair/replacement/troubleshooting actuator procedure link:
http://www.fullsizechevy.com/forums/...king-99-a.html

[dr.gizmo]

When you manually moved the blend door did the air temp change from hot to cold?

[mdfinney1]

No, even manually moving the blend door, does not cause a temperature change.

[dr.gizmo]

I would be looking at the cooling system then. You may have air trapped in the heater core. Vacuum filling is the preferred way to fill a cooling system as air can easily get trapped in todays cooling systems. I would go to a shop that has the right kind of equipment and have the cooling system refilled with vacuum filling equipment.

[sonjaab]

DOC................Those trucks wouldn't happen to have a water control
valve (In the heater hose line) like my old Caddy or Z-28 would they?

[sonjaab]

MD............Are both your heater hoses HOT at operating temp.
going in and out of the firewall ?
Is your cooling system full?
Possibly your cooling system needs to be "burped" to remove a trapped air pocket.

[mdfinney1]

checked it yesterday, and yes both heater hose are hot to the point that you cannot hold onto them for only a few seconds.

I talked with a mechanic at the local chevrolet dealership, and he stated that possibly the blend door is broken, or his thought was if the hoses were not hot that it could possibly be a plugged hose or bad water pump.

Still at a loss.

Marcus

[mdfinney1]

Well,
I went to Harbor Freight yesterday and purchased a heater that will plug into the 12V power supply in my truck, to work until I am able to save enough money to take the truck into the local Chevrolet house and have them look it over to fix it. See Link : http://www.harborfreight.com/cpi/cta...emnumber=96144
I figure that this will work, because I like South of Houston and I mainly use the heater to clear the dew and moisture from the windshield so I can see out in the mornings going to work.