Hi,
I have a 1999 C5 convertible with the dual zone climate control where the A/C stopped working. I brought the car to my friend's shop that has the AC refrigerant recycling system and he ran it on his system twice and told me I he recovered 100% of the refrigerant and that none had leaked out. The driver's side temp door actuator was replaced twice, once in 2007 by the dealer and two years ago by me because it locked up, but is working now as it does adjust temperature up and down and can produce hot heat. There is no cooling on either driver or passenger side. I suspect the blend door might be stuck shut. I can hear the AC compressor click in and the AC button light is on, so I believe the compressor is running. I would greatly appreciate advice on how to proceed, perhaps the troubleshooting procedure to identify if the blend door actuator needs replacement, or to test if a relay went bad, or if some kind of a reboot is necessary. The battery was replaced just prior to this failure. Did losing power to the computers cause this problem? Perhaps the electrical parts are OK and all I need is a reset? My car has only 40,000 miles and looks like new as it spends most of the time in the garage under the car cover. The dealers get $185 for diagnostic time and I think that is criminal! I could replace the blend door myself if need be. I would greatly appreciate your advice.
Thanks,
Neil

 

You might want to post this in the tech section.

 

I will move this to Tech !!

 

First see what HVAC DTC’s you may have and clear them...You can try to recalibrate the actuators...turn ignition off...remove fuse 27 (HVAVCON) for 60 seconds and no less !!...install the fuse...you can try this !!

 

Thanks.

 

I ran on board diagnostics and got 2 codes BO338 HC (inside air temp sensor) and BO 361 (driver's side temp blend door actuator. I was able to erase the sensor code but the actuator code will not go away. I located fuse #27 at the passenger floor fusebox and removed for 5 minutes while I had a beer. No change. I did hear he driver's actuator running when I tried to reset that code, like it was running through its range. That inside temperature sensor is out of production and no one has one new anywhere. I looked all over and found a guy in Tennessee that is pulling them out of old C5s and they might be just about ready to give up the ghost. The temperature control on the driver's side does increase the temperature to very hot and down to the outside air temp, but no cold air out of both sides while the compressor is running. If the driver's side actuator is bad, wouldn't the passenger side still get the AC air? When the driver's side failed years ago the passenger side was cold and driver's side hot. Both get heat but neither get cooling . I wish I had the standard controls, they would be working right now. This complicated system is a failure waiting to happen. Thanks for your help.
Neil

 

Update: when running the on the board diagnostic system I was able to erase the BO338 code that refers to the inside temp sensor but the BO361 driver's side temp door actuator will not erase and when I press the reset button I can hear that actuator running for a few seconds and the code remains. Since this code does not erase, does that mean that I found my problem? The passenger side is not getting any AC cooling either and that controller has no effect what so ever on temperature. The inside temperature sensor is no longer available anywhere. I only found used ones being listed and these may be as old as mine and be ready to fail and I bet the price for a used one will not be reasonable. I'm getting ready to order the Doreman actuator once we come to a conclusion. $100 and a little time isn't too bad. I'll be able to do it if needed.

 

I replaced my driver side temp door actuator (this is the third time replacing it) and all my HVAC codes are gone but still no AC. The new actuator does adjust to create heat and they back down to outdoor temperature but no AC. The system is fully charged with refrigerant, with no codes where do I go from here?

 

Have you verified that the refrigerant side of your system is working? If you do not have an a/c gage set, here is a simple test. Run the engine at idle, high blower, a/c on, and feel the suction line going to the compressor. It should be cold.

 

When the AC stopped functioning I went to my friend's shop where he has the automated 134 system that removes and measures the refrigerant from the system with the engine and compressor not running. He told me I had not lost any refrigerant and there were no leaks. My compressor turns on and is recirculating the refrigerant. At that point I used the on board dianostics and pulled 2 codes BO338 for the interior temperature sensor and BO361 for the driver's side blend door actuator. The BO338 reset itself and BO361 code remained so I replaced that blend door and there is no change. I opened up the old actuator that I removed and the gears are perfect and it performed the same as the new one I just installed. The BO361 code is gone now and on board diagnostics has no HVAC codes, yet there is no cold air. I'll hook up the old fashioned set of pressure gauges run the AC full blast and check the suction side hose to see if it feels cold. They took something that was very basic and made it complicated where there are many more links that can fail to make the system inopperable. The cliche "Keep it simple STUPID" seems to fit the bill here. I have the shop manual downloaded and it looks like I may need their diagnostic tool, or a ohm/voltmeter to take measurements to figure out what broke down in the feedback loop. I appreciate your help. Sometimes I wish I just had my 1969 427 couple where this type of problem couldn't happen.
Thanks,
Neil

 

If the compressor is engaging and the actuator doors are working, then the only sure test is to read the AC gauges and see what you are getting as far as pressures and temperatures. I replaced my complete AC system last year, and it is a daunting task to say the least. It's possible that the compressor is locked up or mechanically not pumping.

 

The reason I suggest you verify you have a cold suction line is because there are a couple of refrigerant side failure modes where the compressor continues to turn and may even sound normal. The compressor is a variable displacement unit. It continuously varies it displacement by automatically adjusting the stroke of the pistons. It does this by sensing the low side suction pressure and trying to keep it essentially constant regardless of ambient temperature and RPM.

Failure mode 1: The compressor will not come off of minimum displacement. If you have this failure, you will have very little cooling because the compressor is hardly pumping. If the outside ambient is warm or hot, your suction line will be just a bit cooler than ambient. If you have a gauge set, you will see a small difference between high and low side pressures. Inside the vehicle you won’t feel much if any cooling. It will seem like a low r134a charge condition but it won’t be low charge. It’s just very low compressor pumping. If your car has this failure mode, you can do all you want with your blend door and it will make no difference.

Failure mode 2: This is NOT your problem based on your description. In this failure mode, the compressor loses it ability to sense suction pressure and just keeps pumping at full displacement regardless of ambient and RPM. When this failure mode occurs, suction pressure is very low, the evaporator temperature drops below 32 degrees F, and you will freeze your evaporator.

One other fairly simple diagnostic you can do to determine if it is the blend door is to pinch the heater inlet hose to prevent hot coolant from circulating through your heater core. If you do this and then you have cool air out your vents, you have verified it is an air side problem.

 

It turns out that there was a loss of refrigerant after all. the system takes 1.5 pounds and the AC equipment only retreived half a pound. There is a leak somewhere in the system. It held a vacuum and I had it charged with red dye so we will be able to see where it is leaking from. I suspect the person that serviced it last did not really know what he was doing and thought he pulled out the full 1.5 pounds. He just saw it would hold a vacuum but that doesn't mean it will hold pressure. He just recharged it with the machine that does not require running the compressor and he never checked the pressures with the compressor running. The driver's blend door that I installed performs like it should and I opened up the one I took out and the gear is fine and I think it is OK. I'll save it as a spare as it is likely one of these blend doors is likely to fail again. I will be watchinig the system closely as I run it. I got 42F coming out of the center AC ducts. I will be looking for the leak with the red dye. Hopefully it will not be the evaporator. The compressor is putting out good pressure. I'm relieved that it was a loss of refrigerant and hoping it is an O-ring that is accessable. Thanks for helping out.

 

Check the schrader valves I have seen alot of systems leak there

 

It's possible but I doubt it. Unfortunately, most times it is the evaporator that starts leaking. It's allot of work to remove the evaporator.

Due to the parts which are required for removal, I would suggest doing all the extra things if you have to get at the coil, to avoid doing it twice.

I did mine last year and replaced everything. Blend actuators, heater core, evap coil, oil sending unit, compressor, condenser, and allot more stuff... Everything that was in a tough spot got replaced. Even the engine mounts were replaced because one was behind the ac compressor.

 

Before you start spending a lot of time and money on replacing parts, here are a few thoughts.

First, why did you have your friend recharge your system and how often have you had it recharged? Every a/c system with elastomeric hose and seals leaks. The refrigerant permeates through the elastomers. Back in the old R12 days when no one cared much about permeation, we had an engineering standard of no more than 1 lb in 40 years for each fitting. The hoses had their own permeation spec per foot of hose too. Even though everything was improved with the environmental ozone concerns, modern systems still lose some refrigerant over time. So did your system slowly lose cooling performance over an extended time? When was it running well and how much later did you notice it wasnt working so well?

The system charge is 28 ounces, 1.75 pounds. So if your friend only put in 1.5 pounds he undercharged it. Then the question is, did your friend actually get 1.5 pounds into the system? Pulling a vacuum and holding it for an extended period of time is an acceptable way to verify your system is sealed. You are right that it does not guarantee it will hold adequately under pressure but it typically does.