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C5 Trouble Codes b)338 and 348

7K views 15 replies 3 participants last post by  The Dude 
#1 · (Edited)
C5 Trouble Codes B0338 and B0348

C5 Trouble Codes B0338 and B0348

I have a 2000 C5. I just recently fixed the climate control unit so I can now read its display. I also replaced all the microlamps in this unit. After completing these tasks, I learned how to check codes and found I had a B0338 (internal temp sensor open) so I replace the internal temp sensor. After completing the temp sensor install I rechecked the codes and temporarily the B0338 code had an H suffix (this was good), but got a B0348 code indicating the solar load sensor was open. This did not appear until after the Internal Temp sensor was replaced. I did try pulling fuse #18 and #27 simultaneously and letting the climate control unit reboot, but now have both a B0338 and B0348 code showing as current. Any ideas or suggestions on how to clear these codes?
 
#3 ·
Hey Junkman, glad you saw my post. I could really use your insight.

Let me update you on my problem. I have the dreaded cold on the passenger side/hot on the driver side syndrome. The only codes I show are B0333 C, B0348 C, and B0363 H. In the last month, I replaced the sunload sensor and external temp sensor in an attempt to clear their respective codes ( 348, 333). I knew these replacements would not solve the hot/cold problem. Last week I replaced the left actuator door (GM#89018365), but it did not solve the hot/cold problem either. As a matter of fact, after installing the new actuator, I could not detect any movement of the motor even after pulling fuse #18 and #27 for the requisite 60 seconds. To test the motor I also cycled the HVAC Control Module between 60 and 90 degrees. No movement detected in the actuator motor Along with the two codes above, I always have a third code B0363 H. I know this is a history code, but whenever I clear the codes, it always reappears as B0363 H.

Since the new actuator motor is not responding, could it be that my HVAC Control Module is malfunctioning and not sending the actuator motor a signal to turn-on? Replacing the HVAC Control Module is not difficult (see my first post) and there are some rebuilt units that cost about $150. Oh, I did check my R-134 and my system is full with no leaks. One other weird symptom, I can clear the B0333 code by pulling fuses 18 and 27. The external reading on the HVAC Control Module reads correctly for about the first 5 minutes of my drive and then defaults to 69 degrees--everytime. The B0 348 code has not cleared even after replacing the sunload sensor. Again, does all this point to a bad HVAC Control module?

I would appreciate your thoughts on this.
 
#4 ·
Have you looked at any of the other threads where I have directed people on how to resolve this problem? You have completely went about trouble-shooting this issue the wrong way and with bad information, not to mention unnecessary parts replacing. I'm curious if you have seen my other threads.
 
#7 ·
Dreadedho/cold syndrome

Thanks to all for your replies. I have seen JM's post on checking the freon level, but did not catch that the system needs to be evacuated and weighted to get an accurate reading. This will be my next step. I will keep you posted on the results.
 
#8 ·
Evacuation and recovery. That has ALWAYS been my step 1 of the process after checking the easy, no cost involved stuff. If you don't, you're working with assumed information and that can be an expensive lesson learned after you get done replacing stuff that you didn't need to.
 
#9 ·
Hot-Cold Syndrome C5

I went today to the shop that did my freon check last month. The owner checked his records and it showed that he had done an evacuation and measurement. He noted in his records that the system was two tenths (.2) of an ounce low. He refilled the system and added the two tenths of an ounce. He checked the system again today and it was at full capacity--no leaks over the last month.

It appears that the freon level is not a contributor to my problem of hot on the driver side and cold on the passenger side.

Again let me restate the symptoms. I'm experiencing:


1. In December I removed the temp control unit and per JM's post re-soldered the eight R241 resistors and changed out all the microlamps. Prior to doing this, I did not check the trouble codes--a mistake on my part.
2. After refurbishing the temp control unit I noticed hot air is blowing out the driver side and cold out the passenger side. I have on several occasions removed both fuse #27 and #18 for extended periods--greater than 60 seconds in the hope that the left actuator door will calibrate itself and resolve my problem.
3. Per JM's suggestion in his post I had the freon level checked and as posted today that appears to not be a problem
4. The sunload sensor has been replaced, but I have the following code related to it B0348 H C. Sunload Temp Sensor Open. Not sure if this existed prior to my work on the temp control unit.
5. I did have a B0338 C code, but after changing the internal temp sensor, I no longer have this code.
6. Since the code B0333 C appeared (After the work on the temp control unit), I replaced the ext temp sensor. Now, it appears to work for about 5 minutes then defaults to 69 degrees and throws the code B0333 H C.
7. The left actuator door was replaced, but it appears the door is not getting a signal to open or close as I have not heard any movement. Even when I pull fuse #27 and #18 for 60 or more seconds and replace them, I do not hear any recalibration movement taking place.

OK this is the list of symptoms and history. What should I do next?
 
#10 ·
I replaced the ext temp sensor. Now, it appears to work for about 5 minutes then defaults to 69 degrees and throws the code B0333 H C.
When you replaced it, did you use dielectric grease? I use it on every connection I take off and reconnect.

Mine used to jump temps around like crazy. Unplugged it and plugged it in a few times, put the grease on it and plugged it back in, and now it works flawlessly.

As for the flapper motor, did it ever work after you replaced it or did it just stop all the suddon?

Also, you mat want to go back and check your unit to make sure you didn't cross any cicuits durring your repair accidently.
 
#12 ·
Hot - Cold Syndrome

I appreciate both posts.

To the one question from C5 Dude, I did not use the dielectric grease. Two questions: Do you put the grease on the sensor connector and then push that connector into the body connector? In other words is the grease suppose to cover the inside of the connector where the electrical contact is made? AND where can you purchase dielectric grease?

To the one from JM: When I replaced the left actuator motor, I did rotate the door shaft manually and it seemed to travel easily from one stop to another. I did not do it with the AC on--that would have been smart, but I was running out of day light and needed to button things up.

To the other question, about whether the system was working correctly before I did the work on the HVAC Control Module, I'm pretty sure it was. Since it is winter, I would not have found it odd to have hot air blowing out the driver side, but this summer I know the AC was working fine. I did not suspect there was any problem with the hot/cold syndrome and really did not check prior to starting work on the HVAC Control Module. My only objective was to get the display on the HVAC Control module to light-up.

I'm going to have to carve out some time to get back under the dash and see if I can manipulate that actuator door with the AC on. If I get cold air out the driver side, I guess that would eliminate the R-134 problem. Thanks for leading me through this process. I also appreciate good diagnostic work and my wallet especially appreciates it.
 
#13 ·
One thing that I forgot to mention. Your AC will not work properly if the outside temperature sensor is not working correctly. The HVAC will not allow the AC to come on if it thinks that the outside temperature is below a certain value (I can't remember exactly what that value is). If you try and run the AC when the outside temperature is cold enough, the LED on the AC button will flash a few times and then stop. The AC itself will never come on. This is a designed feature of the HVAC system. The reason being, you can drive a car with no AC all year long. However, you CANNOT drive a car in the winter time without heat because you can't defrost the windows. That's why all HVAC systems today default to heat if something goes wrong with them.

So before trying what I said to try, make sure that the outside temperature reading is correct. I am also attaching another bit of information that may come in handy.
 

Attachments

#14 ·
Hot/Cold Syndrome

Thanks JM. The bulletin was very useful. I have one more thing I would like to bounce-off you. When I did the initial resoldering of the 241 Resistors in the HVAC Control Module, I wanted to check and see if I had done the soldering correctly. In my haste, I plugged the connector into the back of the module and misaligned the pins and connecter by putting the connector over just one row of pins instead of over both rows. Not knowing this, I turned the ignition on and got in just a few seconds several crazy error messages like high current condition, exceed performance limts, and others like this. I immedaitely shut the ignition off and discovered the misalignment. Is it possible, I did some damage to the large IC in the module that controls functions like the opening and closing of the actuator doors an drthe input from the solarload sensor and outside temp sensor? I had forgotten about this mishap and it just popped back into my head.
 
#16 ·
Thanks JM. The bulletin was very useful. I have one more thing I would like to bounce-off you. When I did the initial resoldering of the 241 Resistors in the HVAC Control Module, I wanted to check and see if I had done the soldering correctly. In my haste, I plugged the connector into the back of the module and misaligned the pins and connecter by putting the connector over just one row of pins instead of over both rows. Not knowing this, I turned the ignition on and got in just a few seconds several crazy error messages like high current condition, exceed performance limts, and others like this. I immedaitely shut the ignition off and discovered the misalignment. Is it possible, I did some damage to the large IC in the module that controls functions like the opening and closing of the actuator doors an drthe input from the solarload sensor and outside temp sensor? I had forgotten about this mishap and it just popped back into my head.
You will definately need to get a loaner module to swap out to check everything. That thing very well could be toast. You might want to check craigs list for parts cars and local yards.

Also, you can get dielectric grease from any of the parts stores.
 
#15 ·
Of course that's possible. You could have also dropped a blob of solder onto the board somewhere. These things are always possible. Problem is, you have no way of testing the HVAC without using another one. When you consider the different voltage values that run the HVAC, there's no telling what damage doing what you did could have done.

By the way, when doing the recalibration, make sure that you only remove the ONE fuse as the direction call for. You are removing two, which is incorrect.
 
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