Erratic Climate Control?

Tiny
300MAN
  • MEMBER
  • 2007 CHRYSLER 300
  • 3.5L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 296,000 MILES
After the car runs for 15 to 20 minutes there is a single click that can be heard behind dash and immediately the temperature and mode climate controls become unresponsive. (Also, the two actuators on driver side. I know this because I have looked under the dash when the system is down, and neither actuator will be moving anything) However the fan speed will respond and the A/C will kick on if you push the A/C button. The car is a single zone system, not dual. I have already put a new climate control module/panel into the dash and replaced the mode actuator. I have not yet replaced what I think is the blend door actuator which is way up under the dash and very hard to get to. Strangely enough, if I turn the car off and then restart it all the controls will immediately begin working again, usually for a few minutes until I hear another single click behind dash and then the above mentioned controls and both actuators quit responding again.
Monday, January 22nd, 2024 AT 2:34 PM

8 Replies

Tiny
BORIS K
  • MECHANIC
  • 836 POSTS
Hello,

As the HVAC system shuts down part of its controls the control module is "seeing" an issue and therefore would be setting fault codes, DTC.

Before wasting more time and money replacing components, I would suggest first carrying out a CAN scan using a suitable diagnostic tool. Once done please post the fault codes on or site for further evaluation.

How to scan:
https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Cheers, Boris
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Tuesday, January 23rd, 2024 AT 12:53 AM
Tiny
300MAN
  • MEMBER
  • 8 POSTS
Thank you, Boris. I forgot to mention that when this first started occurring, I took it down to a mechanic friend who has one of the necessary scanners to detect climate control codes. There were no codes showing. Not sure if he tried the scanner while the climate controls had switched to inoperable or not. If he plugged it in while climate controls were still operable would the codes still have been saved and show up or should I have him rescan it when the controls are not working?
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Tuesday, January 23rd, 2024 AT 7:58 AM
Tiny
BORIS K
  • MECHANIC
  • 836 POSTS
Hello,

Fault codes usually remain stored as long as a battery disconnect/flat battery did not happen.

I would suggest to try another scan of the HVAC system when it is acting up.

For reference the blend door actuator is located just above the mode door actuator.
For trial you could fit the old mode door actuator in place of the blend door actuator.

A video:
https://youtu.be/TqGvr9vq2cg?si=NyER4-3gvheHSEj3

Cheers, Boris
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Wednesday, January 24th, 2024 AT 3:33 AM
Tiny
300MAN
  • MEMBER
  • 8 POSTS
Thanks Boris. Like you suggested I had been giving some thought to using the old mode door actuator which I had already replaced ( and which turned out not to be the problem) up at the blend door location instead of buying a new blend door actuator. I’ll see about my friend rescanning it first if he says he did the scan during a period when the climate controls had temporarily come back on due to the car being restarted, rather than during an inoperative period. The blend door actuator will be a very difficult replacement due to its location but I’ll have to give it a try unless another scan actually shows code(s) that indicate a different issue. Am hoping it is not the blend door itself sticking.
Question- are there any relays in either the engine or trunk fuse boxes that interact with the climate control system or perhaps any climate control modules/relays up under the dash that I have missed? I’ve looked closely but have found none.
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Wednesday, January 24th, 2024 AT 5:20 AM
Tiny
BORIS K
  • MECHANIC
  • 836 POSTS
Hello,

The blend and mode door actuators are directly controlled by the HVAC control module.
The HVAC control module is powered by fuse F41(10A) and fuse F14(10A) in the trunk fuse block.
Fuse F42(30A) supplies the blower motor with 12V ignition via dark blue wire to pin 2.

The only relays you have are for the AC compressor clutch and cooling fan activation.

Pin out at HVAC module connector C1(16 pin)
Pin 1, dark green/pink wire 12V ignition from fuse F41
Pin 2, red/yellow wire Constant 12V from fuse F14
Pin 3, black/light green wire Ground

Connector C2(12 pin)
Pin 1, orange/dark blue wire to mode door actuator pin 6
Pin 2, dark blue/orange wire to mode door actuator pin 1
Pin 5, white/dark blue wire to blend door actuator pin 6
Pin 6, dark blue/white wire to blend door actuator pin 1

Cheers, Boris
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Thursday, January 25th, 2024 AT 4:03 AM
Tiny
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Thanks Boris. I’ll keep you posted.
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Thursday, January 25th, 2024 AT 5:12 AM
Tiny
300MAN
  • MEMBER
  • 8 POSTS
Boris, I went ahead and replaced the blend door actuator and took the Chrysler 300 for a 45-minute drive. All the climate controls worked throughout the trip instead of the temperature and mode controls shutting down after about 15/20 minutes as had been the case. At this point it appears that the problem is corrected. Thanks again for your advice and assistance.
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Friday, January 26th, 2024 AT 5:28 AM
Tiny
BORIS K
  • MECHANIC
  • 836 POSTS
Hello,

Thank you for the positive feedback.

Cheers, Boris
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Friday, January 26th, 2024 AT 6:16 AM

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