Possible plugged heater core or bad EATC?

[LJRuddy]

Picked up a 96 SHO with 236k. Car sat for over a year due to a coolant leak. Got that fixed and the car is now driveable.

My issue now is the heater. The engine warms up normally, cooling fan kicks on when the upper hose reads ~185 on my temp gun. However, I cannot get any heat from the heater. The engine has gone through 4 heat cycles since I replaced the coolant and the fluid level has not changed at all. Do I have a plugged system somewhere (heater core) or could the EATC not be switching to hot when I adjust the heat? Is there a test I can run on the gen 3 EATC like you can on the gen 2? I'm fairly confident that there is no air in the cooling system as the engine temps are all normal according to my temp gun.

If I do have a plugged core, what product would you recommend to flush the coolant system out? I usually just flush with water but I feel like the possible plug is a bit more severe since I've heated the car up several times and nothing has broken free.

EDIT: Found the self test on v8sho.com. EATC displayed 024 and 022 fault codes. Is my BDA bad?

 

[kevinspann]

http://www.shoforum.com/showthread.php?t=111420

I guess the heater core could be plugged....I don't recall how access to the hoses are, but I'd put the temp gun on them and see if the inlet hose is the same temperature as the outlet.

If it needs a heater core or a BDA, you'll figure out why gen 3 > gen 2.

 

[TimboSHO]

Very common to have a plugged heater core. The best stuff to flush it? Toilet bowl cleaner. Disconnect both hoses and fill it up. Don't let it sit more than 10 minutes and flush it out with lots of water/air.

What happened to the Honduh?

 

[LJRuddy]

Very common to have a plugged heater core. The best stuff to flush it? Toilet bowl cleaner. Disconnect both hoses and fill it up. Don't let it sit more than 10 minutes and flush it out with lots of water/air.

What happened to the Honduh?

About 2 weeks after I swapped the engine, I was coming home from work and saw a deer standing in the middle of the road while I was on a sweeping left turn. Roads were wet and I tapped the brakes just enough to cause the rear end to kick out from behind. Went sideways and backwards into a creek bed. Totaled it. :-/

 

[Mr Anonymous]

I don't know the EATC codes off the top of my head but a bad BDA or football is certainly possible. Easiest thing to do first is check the heater core.

With the engine warmed up, reach in and grab the two lines going to/from the heater core and see if they are both hot, or if one is hot and the other isn't. The easiest place is probably right behind the EGR valve. The two lines are right next to each other (one should be bolted to the surge tank).

If they are both hot then the heater core is fine. Let us know what you find.

 

[LJRuddy]

With the engine running and heater set to full hot, the upper radiator hose reads 170F. The top heater core hose reads 150F and the lower reads 145F.

The 022 and 024 codes are:

022 - A/C Electronic Blend Door Actuator Short.
024 - A/C Electronic Blend Door Actuator Fault.

Weird that both hoses are similar temps but I'm getting room temp air. Showing about 67F from the defroster. Ambient temps are 34F.

FWIW, I still don't have any pressure in the cooling system. Drove it about 10 miles to the gas station and back so the engine got up to operating temps.

 

[SHOdded]

Are you sure someone didn't bypass the heater core?

 

[Mr Anonymous]

A 5-degree difference is a good sign that your heater core is fine. A bad BDA can definitely cause your issue if the door is stuck on cold. IIRC the BDA can be replaced by just removing the football and/or center console. In fact, I think if you remove the football, you may be able to disconnect the BDA and manually adjust the door to give you heat until you can properly repair the problem.

 

[LJRuddy]

Got the football out... Is the BDA the black box in the middle of the first pic? Its the module that has the white square electrical connector on it, right?

The adjustment lever is seen in this pic?

Which wires on that plug should have power going to it and how many volts? I'd like to see if the module is bad or if I'm not even getting power to it.

 

[Mr Anonymous]

Yes, that's it. I'd just unplug it for now and manually adjust the door to your comfort level. I'll see what the diagrams show tonight.

 

[LJRuddy]

I unplugged it and took the lever off of the plastic dial as I was unable to move the lever up or down. No matter which way I rotate the **** on the evap housing, I still get the same temp air blowing through. There doesn't seem to be much friction when rotating the actuator. Could something else be broken? The spring that attaches to it is more than enough to 'snap' the dial back to it's resting place when I let go of it.

 

[Mr Anonymous]

The door itself might be broken. It's been so long since I had a gen 3 heater box apart that I can't remember what's where, etc. I'll see what I can find on the service DVD tonight.

 

[LJRuddy]

I hope that isn't the case. Really do not want to take a dash out of this car.

 

[kevinspann]

I hope that isn't the case. Really do not want to take a dash out of this car.

Gen 3 dash > gen 2 dash, thanks to bulk head connectors. There are no wiring harnesses passing through the firewall. The hardest part is getting the center console out of a gen 3. Beyond that (hvac box) I can't help much.

 

[Mr Anonymous]

The diagrams of the heater box on the service DVD aren't really helpful. It's been 3 or 4 years since I last pulled a V8 dash, so I can't even help give you a step-by-step, but if you just take your time and have a second set of hands to help pull the dash out of the car you should be OK.