Brad Kirby

When I bought the car in February, I noticed it would blow hot from the driver side and cold from the passenger side. The head unit appeared to function normally except the back lights didn't work so I couldn't see the buttons in the dark. I found a thread here about the issue and pulled the codes, I think I had the B0441 and B0446 codes (if memory serves) so I pull the fuse #27 and waited a few minutes to put it back in. Once I put it back in, all of the lights on the head unit started flashing. Several more fuse resets and a couple of battery resets and the problem persist. Every time I turn the car on the a/c compressor comes on (it didn't do that before the reset) and I can still turn it off with the button. I checked and charged the a/c (I have manifold gauges and charged it according to ambient air temp) and did a couple more fuse resets and still have the flashing lights. I pulled codes again and get six
B0332
B0337
B0361
B0365
B0441
B0446

I'm starting to lean towards the head unit being the issue but I thought I would ask for suggestions here before I dropped even more money on this car. Also, I called the dealer about getting the head unit rebuilt and he can't even tell me how much it will cost. I gave the last eight of my VIN and it seems they haven't rebuilt this one before, go figure. Here I thought they were the same from 98-04. I was hoping to find one used so I didn't have a hole in my dash for an indeterminate amount of time, but no luck there either.

I have to pull the dash to replace the heater core (why does GM insist on using Dexcool?) so I planned to replace both blend actuators at the same time. I think they are both the same part number, but I can't find info on that either. When I look up listings for the actuators, it just says, "main".

Brad Kirby

So, no one has had this mix of codes before?

SilverC54me

Ok, you have 4 distinct issues. The inside and outside air temp sensors and both temperature actuators. After the codes will be a H or C or HC which designates the status of that error. H is history, C is current and HC is History and Current.

B0332 Outside Air Temp Sensor Short to GND

B0337 Inside Air Temp Sensor Short to GND

B0361 Left Actuator Feedback Short to GND
B0441 Left HVAC Actuator Out of Range

B0365 Right Actuator Feedback Short to GND
B0446 Right HVAC Actuator Out of Range

I would first check the wiring harness that is plugged into the HVAC controller. Look for damaged wires. If there are none, clear the codes and then disconnect the connector from the HVAC controller and wait about 5 min and reconnect. Check the operation of the system. Recheck codes to see if any reoccur.

If you do not find any wire damage, it is more likely to be the HVAC controller. All dual zone controllers from 1997 to 2004 will fit your car.

Gary

BTTBSS

Sounds like you have other issues but Kincers Service, LLC in Owensboro, KY rebuild my AC head for $ 125.00. If you need to have yours done. They are fast and have done two cars for me.

Brad Kirby

I don't know why I forgot to post it, all codes are HC.

I don't know if it is related, but my autodim mirror doesn't work and neither do the map lights. Perhaps they share a ground with the HVAC. The dim amber lights under it are on, though. Anyway, my new blend door actuators will be here later today so I will be removing the dash to do the heater core and replace the actuators. I'll clean up any grounds I see under there while I'm at it.

sjhanc

I had the same codes in history when I bought my C5 last year. I followed the recommended methods to reset the HVAC but none worked until I read the owner's manual and found a reference to set the driver's temp control to 73 degrees and the passenger's to the middle position. After doing so and doing the fuse/battery disconnect the AC began to work with cool air from both sides. The only actual bad part was the passenger's blend actuator which cycled continuously. I pulled the dash pad and installed a new actuator, the AC has functioned correctly ever since. I had previously installed a new fan speed module but I don't think it was needed.

Even though the AC worked normally it was slow to cool the car, recently while working under the front end I discovered that the two radiator/AC cores were clogged with large grain dirt and grass debris. I removed the fan housing to clean the cores by backflushing with water pressure. I got a huge amount of crap from the cores and now the AC cools the car quickly in the 100 degree temps common in Florida. A big side benefit was that the engine's operating temp dropped from 235 F in city driving to 190-205 F. The highway operating temp never exceeds 180 F now at 80-90 mph Interstate cruise.

I had replaced the engine thermostat with a 165 F part but it had no effect on the operating temps. I also flushed the radiator with no effect. I was in the process of deciding what aftermarket radiator to buy to lower the engine operating temps. Now that it is running cool with the stock radiator I won't bother. If the radiator ever leaks I'll put another stock radiator in and keep it clean.

In my opinion, the slanted radiator core traps large debris that would just drop out of a vertically mounted radiator. Yearly back flushing of the Vette's cores is probably a good idea. In my car, there was a considerable amount of organic debris trapped between the cores, I was unable to get all of it out. The AC core needs to be removed to get it all out.

Brad Kirby

Some of the Ebay listing for rebuilds say the head unit is not rebuildable if it blows different temperatures from both sides or doesn't blow from the correct vent. The listing I found for a used head unit says it fits 1998 and 1999, I thought they were the same for all years. I think it was listed that way on Corvette Mods as well.

I replaced the heater core and put a new AC Delco actuator on the passenger side. I moved the old passenger side actuator to the driver side. I got it back together and it has the same problem. The passenger actuator doesn't move at all (it didn't before) and the driver actuator moves, but doesn't appear to change anything. I still get hot from the driver side and cold from the passenger side. The a/c is charged and there is no air in the cooling system. I saw no damaged pins in the rear of the head unit and no obvious wire damage. When I had the dash out, I looked in the book for the wire that is ground at the head unit, tested good. I also did a continuity test for the signal wire from the head unit to the passenger actuator, tested good. The display lights on the head unit still all flash and trying a few more resets (even though the battery wasn't hooked up for two days) did nothing.

After I did all of that work, the steering rack started leaking. I am really hating this car right now. So, I don't want to spend $600 on a head unit to find it won't fix the issue. I'm open to suggestions. I've got time to try a few things since I'm waiting on a rebuild from Turn One.

sjhanc

Brad Kirby,
Have you checked the ac vacuum feed located behind the ECM in the right fender?

Brad Kirby

I had to disconnect the line to remove the dash, I didn't see any breaks i the lines and I don't hear any vacuum leaks in that area. I checked under the battery tray (early on when I first had this issue) and didn't see any breaks in the line.

The Rabbi

My neighbor just had his rebuilt in Fl for $170, incl. all new bulbs. PM me for the contact info.

GSTexas

Same issue for me last week on my C5. Pulled the fuse in the passenger foot well and disconnected the battery for about 1/2 hr. Whola my issues were solved cold air out of both and so far no codes have returned.

sjhanc

Maybe you could find some one local who has a spare HVAC unit and swap them to see if it fixes your problem. I know chances of this are remote but this would be a simple way to diagnose your car. You also could talk to one of the rebuilders to see if your unit could be checked for proper function.

I would disconnect the parts that have 'short to ground' codes, clear the codes and run it to see what changes (if any) show up. If there ARE different codes set that would indicate that the control unit IS functioning and you may have a wiring problem elsewhere. When I was chasing A/C problems (and other issues) in my car I found a loose ground nut in the ground located under the driver's bottom door frame trim. After cleaning the connectors and tightening the loose nut several codes disappeared and dead stuff began to work properly. That is when I found that some relays were missing (I think his mechanic pulled them when he was unable to diagnose the problems). Replacing the relays got rid of more faults.

1235Punta

2004 C5, manual HVAC controls, AC blows out very cold air, except drivers side blows out ambient temp, passenger side cold. Doesn't matter what you adjust the passengers controls to. Drivers vents no change in temp even tho the temp control seems to work just fine. Which fuse did you pull? Do you think I have the same problem you had?

Ed Ramberger

Do yourself a favor and get in touch with Travis Wolfe at Vetteronics. He knows these units, rebuilds them for a very fair price and has the ability to test them. Many "rebuilders" don't even realize the bulbs they are installing are a fraction of the resistance of OE and the result is hot displays, melted buttons and pulling more current through the boards in the units.

Send him an email - he is very busy but he will get back to you. Here is a link to his site. Explain to him what you have going on.

Also, there is another fuse for the HVAC circuits. My 04 has fuse 27 & 18. I believe 18 was for the sensors.

Turn the HVAC off, remove the key, pull the fuses, install the fuses, turn key to run (do not start) and HVAC will go through a calibration. You will hears the doors moving, then the unit will start blowing air - takes less than a minute.

https://www.ebay.com/itm/C5-CORVETTE...IAAOSwrMlZeBBO

001pewter

That usually indicates low freon, had the same problem. Replaced low side Schrader valve, after finding out it leaked, and refilled freon. No problems since.

Vetteman Jack

Moved to C5 Tech.

Corvette#2

[QUOTE=1235Punta;1596029618]2004 C5, manual HVAC controls, AC blows out very cold air, except drivers side blows out ambient temp, passenger side cold. /QUOTE]


I've had that problem intermittently. Except on mine the symptom is the drivers side is cold and the passenger side is hot. It's happened maybe 4-5 times in the last 3 years. It's done it both before and after I got a new compressor and replaced a slow leaking schrader valver on the low pressure side.

I believe it's a problem with the door blend actuators.

Luckily, mine always seemed to resolve itself within a few days. Now to baby it, I don't mess with the mode controls. I turn the AC off and on, as needed, and adjust the fan speed, but I don't switch modes or use the heater. Basically to leave the actuators as they are. I've read replacing the actuators is quite a job, requiring one to remove the whole dash.

huesmann

Pull codes. If you have a B036x you have a problem with a blend door actuator.

1235Punta

Will do, Many thanks.

1235Punta

[QUOTE=Corvette#2;1596032475]So, I can blame my problem on my lovely passenger that's always messing with the passenger side control? I'll dig into the manual to see what's involved. Thank you.