Ironman433

Does this mean it's time to replace the HVAC unit or...??

99-HVAC - Heater, Ventilation, Air Conditioning

B0361 Left Actuator Feedback Short to GND H
B0365 Right Actuator Feedback Short to GND H
B0367 Right Actuator Feedback Open H
B0441 Left Actuator Out of Range H
B0446 Right Actuator Out of Range H C

If I clear the codes and let it recycle - it still blows hot out of one side and will show NO CODES. Turn it off and check the codes and the same 5 codes pull up...

pewter99

have you tried disconnecting the battery?

I am one of those who couldn't get my hands in there to replace the actuator so I opted for a head unit from an 01 and up as they have a built in logic that compensates for the actuator issue..I have one from an 04 Z06 in my 99

Ironman433

No... I haven't tried that but I've had to play games with it for years - clearing the codes periodically and then turn it off, turn the left temp controller all the way down a few turns and then Auto and it would work... DON'T TOUCH IT!! Awwwww, man...

Reset... Reset... Ahhhhhhhhhhhh...

QCVette

I had not heard of this head unit upgrade before. Can you tell us more?

Is it a direct swap? (same connectors and everything)
Does it work to keep the actuators positioned correctly?

I have a '99 that had some issues, but by clearing the codes and resetting it, I was able to get it working normally. But if there is a better fix I would like to consider it since I expect the issue to return.

Thanks.

Ironman433

I tried clearing the DIC Codes (several times) and read another thread about Re-Calibrating Actuators:

Use the following steps to perform the calibration update:

1. Turn OFF the ignition.
2. Remove the battery positive voltage circuit fuse of the HVAC Control Module (fuse #27). This fuse is located in the passenger's side floor board area.

Important
The module memory will not clear if the battery positive voltage circuit fuse is installed in less than 60 seconds.

3. Wait 60 seconds.
4. Install the fuse.

It blew out ice cold on the driver's side and cool on the passenger's side so I checked the DTC Codes and HVAC still had 3 of the 5. (I didn't take the time to look and see which ones before clearing them) Then it blew out nice and cold on both sides. I also left the A/C on as I was clearing the codes.

This isn't the first time that I've done the DTC Code clear to get it to work right and my Digital Control Center has no display at all so I'm wondering if I need to replace the dash controller and both actuators to fix this?

I looked on eBay and didn't see an HVAC Head listed so I'm not sure what the story is on that option...??

pewter99

direct swap...I forget how I learned about it but I bought one from someone here $125 a few years ago...plugged it in and no more problems...thats all I know

Ironman433

Which unit is the head unit...?? The HVAC Control Assembly on the dash under the radio or what?! It's just that digital display unit and two actuators as far as I'm aware! (That's not saying a whole lot actually - there could be 50 more parts for all I know...?? ) LOL

Ironman433

This unit here - correct?

Bill Curlee

When your car was NEW,,,,,,,,,,, your HVAC unit worked 100% perfect. So,,,, if you correct the ISSUE causing it to screw up, it will work perfect again.. 90% of the time ,, its the actuators that fouls up.

So, The first thing I would do is pull them out and inspect them.. Open them up and look for broken gears and or damaged components and circuit board solder points.

. Some people have epoxied the damaged gears when they crack

Ironman433

I found this article at Corvette Central that may be of help:

The four most common A/C problems C5 Corvettes experience (aside from low Freon levels) are air delivery problems, temperature control issues, malfunctioning A/C control panels, and compressor failure.

Air delivery problems are generally the result of a loss of vacuum. These problems range from the relatively benign to potentially catastrophic. On the minor end of the scale would be vacuum hoses that have been inadvertently disconnected. If you or another person recently worked near the rear of the engine, for example on the intake manifold, it is quite possible that a vacuum line was either intentionally or unintentionally removed. Oh, if we should all be so lucky that the issue can be resolved so simply! Unfortunately, on the other side of the spectrum there are the nightmare scenarios such as an extensive battery acid leak. These situations are not to be taken lightly because not only can they damage vacuum tubing and cause a vacuum leak and subsequent A/C issue, they can severely damage your main electrical harness, Powertrain Control Module (PCM) and Traction Control Module (TCM) that reside under the battery. Here is to hoping that your air delivery problem is only the result of a minor vacuum loss!

This is the back of the intake where the oil sending unit is located. Notice the vacuum fitting adjacent to the oil sending unit. If you or someone else has recently worked in this area and you now have a vacuum leak and A/C troubles, this is definitely an area to check out.

The main electrical harness, Powertrain Control Module (PCM), and Traction Control Module (TCM) are housed beneath the battery and battery tray, making battery leaks a costly affair. To sleep soundly at night, a battery mat ( Corvette Central part number 171002) is highly recommended. The mat absorbs battery acid and neutralizes it.

An inability to obtain the temperature you desire is usually the fault of the electronic temperature door actuator. A faulty electronic temperature actuator can easily cause vehicle occupants to believe they are experiencing a health problem because the temperature is likely to randomly alternate between cold and hot. Another failure is a complete lack of temperature control. Two blend actuators, (part number 455093), are required per car.

Before you replace the electronic temperature door actuator, check to make sure that the door is not sticking. Replacing the actuator is a moot point if the door is stuck. A set of pliers can be used to test the operation of the door; using a set of pliers on the rod is a more accurate way of ensuring that the shaft is not binding. To date, we have not encountered any binding or stuck door issues, but anything is possible.

This is another common problem many C5 owners face. It certainly is difficult to set the HVAC system to your desired temperature when the control panel is entirely blank. In this case, you will need to either replace the A/C control panel or have it repaired. Cold solder joints and failed backlight bulbs are the typical problem. Fourteen incandescent along with five LED bulbs are soldered into the circuit boards. Like all incandescent bulbs today, don’t expect them to last more than five years. Intermittent lighting of the center LED display is a dead giveaway that there are cold solder joints acting up.

Corvette Central can repair the digital readout of the heater air control for you; just look for part number 455220. If you would rather replace the unit, you can order part number 455113 for 1998-1999 Corvettes and part number 455055 for 2000-2004 Corvettes.

The last of the most common C5 A/C issues is compressor failure due to leakage. Compressors are the workhorses of the A/C system and are subjected to high temperatures and high PSI in their efforts to keep us cool. In the early stages of compressor failure, you will likely notice diminished cooling as the refrigerant level drops off. Remember this bit of advice: every time refrigerant leaks out, so does a portion of the system’s lubricating oil. Topping off the A/C system annually without adding lubricant assures a slow compressor death. At that point you may notice belt squealing as the compressor seizes.

Amazingly, compressors utilize just a few ounces of lubricant. In fact, adding too much oil can be detrimental and should be avoided. Of course, not having enough lubricant is also a problem. Lubricants can either be installed in incorrect amounts (too much / too little), leak from hoses or connections, or break down due to contamination. If you replace the compressor, be aware that any debris left over from a previous failure can shorten its life. It is highly recommended that you thoroughly flush the system before installing the new compressor. Corvette Central sells a new A/C compressor with clutch pulley, part number 455146. The A/C compressor hose, part number 455234, is also available if the current hose is in poor condition.

Anytime the refrigerant system is opened up, A/C accumulator replacement is mandatory to ensure minimal moisture in the system and that clean refrigerant is coursing through the system. The A/C accumulator acts as a filter; if the A/C system is opened, moisture can enter the system and cause havoc. To order a replacement, use part number 455034.

This compressor has an obvious leak, but keep in mind that compressor troubles may not always be this straightforward. There is green tinted lubricating oil on the A/C high side aluminum tube, indicating that refrigerant oil is being blown out of the compressor case seals. This is very common on high mileage C5s.

Replacing the A/C compressor is quite difficult due to space constraints. Once the mounting bolts are removed, it takes some wrangling to get the compressor out of the engine compartment. There are A/C do-it-yourself recharge kits with and without oil charge that can be used for a system top-off, but these kits are not recommended after compressor replacement. A certified A/C shop should evacuate the system and install the correct amount of A/C refrigerant. Control panel removal and electronic temperature actuator replacement will require most of the dash to come apart.

Bill Curlee

Excellent write up!!

Bill

CorvetteCentral.com

Here is a link to the complete blog post, with images: http://tech.corvettecentral.com/2013...ioning-issues/