2001 GS with heater problems

2001 GS with 3.8 – approx. 110K

The heater has quit and I want to make sure I’ve covered all bases prior to replacing the heater core.

- Hoses going into firewall are both hot (in and out).
- Cooling system has been flushed and new coolant added.
- A/C works
- Does not work either in single or dual control mode.

Any suggestions would be appreciated.

Thanks,
Duane

Best thing to do is pull the inlet and outlet hoses at the heater core firewall side and check for flow or try forward and/or back flushing only the heater core. You will be surprised what comes out. But make sure the pressure is not too high if using the city water supply. Unless you have coolant under the driver's or passenger side carpet indicating a leak it is not uncommon for the core coolant passages to get blocked after a main cooling system flush so maybe you can save the trouble of replacing the heater core which is a PITA. It is constant flow in to and out of the heater core with no check valve.

I am getting ready to replace one this weekend in the '99 LS but it is leaking and the heat was fine. I got one off of EBay for $65.00. The original OE one the factory installed but new. Delphi part number HC0379.

Also, you could check at least the passenger temp actuator to make sure it is working while adjusting temp on the climate control unit. Just drop down or remove the glovebox and use a good flashlight for inspection.

Thanks,
I'll check that - the heater wasn't working when I had the system flushed.
I'll pull the hoses and check the flow myself.

Thanks again,
Duane

Well, I checked flow through core and it seemed to flow without restriction and the immediately after the coolant came out the water was crystal clear.
I've got the glove box out to check the actuator, but I'm not sure what to look for - I've looked in there and changed the temp from high to low back to high and don't see anything mechanical happening. Can anyone give me a hint to help me see it working?

Thanks,
Duane

Then it may not be a heater core or flow issue in to or out of the heater core.

When you manually adjust the passenger side temp on the climate control unit you should see the center of the temperature actuator move and may even hear it. If not then the reference signal needs to be checked or the ACC may need to be re-programmed by the dealer.

I've checked what I believe to be the actuator by manually adjusting the temperature from 60-90 and by also setting it to "dual" and adjusting the passenger side from cold to warm. The center area (looks like a metal ring) does not move (rotate) at all. I was going to attach a photo of a part that I believe to be what you were asking me to watch, but I guess I don't have the ability to post attachments.

I'm not sure what you mean when you mention checking the "reference signal" nor am I familiar with the ACC that might need to be reprogrammed. Can you help me a little more regarding that? Thanks - Also, could this part be bad?

All help is appreciated.

Thanks again,
Duane

Did some more playing around - just for kicks and giggles I pulled the actuator off from the passenger's side and manually moved the vent control. Now I got 90 degree air on the passenger's side and 60 degree air on the driver's side. I took the actuator apart and the gears are fine so it would appear that the actuators are not getting a signal to move.

Duane

Hi Duane,

I agree. It sounds like the actuator control signals from the climate control unit are missing. I'll check the Regal Service Manual and see if there is anything else to check and how to measure the signals.

Looking in the manual (got one but don't always know what I'm looking at:screwy:) - pg. 1-245 : Re-Calibrating Actuators - it states to:

1. Turn OFF the ignition
2. Remove the battery positive voltage circuit fuse of the HVAC Module.
Wait 60 seconds and then reinstall the fuse.

The Schematics for the Temperature Actuators is on page 1-125 and it appears that the fuse that supplies them is B3/B4 however this is a "Hot to RUN" circuit. I tried that fuse, but no results.

It seems that the term "battery positive" would mean that I should be looking for a "Hot at All Times" fuse. Am I on the right track?

Thanks
Duane

Do you have the GM FSM 3 volume set? Pretty tedious sorting through it.

Another reset procedure for the CJ2 ACC is:

1) With ignition to ON, make sure ACC climate control is turned off manually. Turn ignition to OFF.
2) Disconnect battery negative cable for several minutes.
3) Reconnect battery negative cable.
4) Ignition to START and ACC climate control to on, adjust temperature after sufficient warmup and test.

This is supposed to reset the actuators with the ACC. If this doesn't work then you have an issue with the programmer in the climate control unit.

Yep, I've got the 3 volume set - with the virtually useless index. :iceslolan

Tried the other reset procedure for the CJ2 ACC and no change.
Interestingly - when I reconnected the negative battery cable and turned the
Ignition to START the ACC climate control unit immediately went to AUTO, even though I had stopped it with the unit on OFF.

So, if my issue is with the programmer in the climate control unit is that going to require a new HVAC control module?

Thanks,
Duane

Since you have the FSM about all you can do is follow the procedures at around page 1-201 and up (HVAC System) or Volume 1 Chapter 1 since our pages don't match. And if the steps take you to the bottom or final steps then the climate control unit would be the logical choice from what I see.

Thought I'd update this in case someone else finds it via a search.

My problem was indeed the vent door actuators - both of them.
I had problems wrapping my head around both of these actuators going bad but that was indeed the case. I even ordered the actuators "one at a time" to make sure one bad one wouldn't cause the other not to work. If you've priced these you'll understand why - dealer OEM cost - $250 each. Found a web store that sells them for $130 each - AC/Delco OEM.

In the process I also acquired a dash controller for the ACC that at least was cosmetically better than the original.

That said - I now have the old ACC controller and two non-functioning actuators. I've seen some web traffic on these actuators and it appears that occasionally there is a problem with broken gears - I took one of mine apart and the gears are intact --- so, if anyone want these parts you can have them by paying for the shipping from Mississippi.

Thanks for all the help I get here.

Duane