I have a 2014 Challenger R/T 6 speed. The A/C compressor clutch never disengages causing the lines to freeze even when the heat is at full blast. I have a scan tool and can see that the PCM is sending a on/off signal. The only way to get it to turn off is to unplug it. I'm sure its grounded somewhere after testing the wires. Looking at the schematics there is no relay for the compressor. I think it may be in the relay box as that's where the signal from the PCM runs to. But with it being a circuit board inside of the box it seems unlikely that's where the short is. Has anybody had this issue? Or maybe somebody has a better schematic for the compressor that will help.
So when you say, "...causing the lines to freeze even when the heat is at full blast.” do you mean the evaporator is freezing over? It would be nearly impossible for the lines carrying the refrigerant to/from the evaporator to freeze.
On the other hand, having the evaporator freeze over can happen when a “superheat” condition has been reached within the system, and an A/C compressor that continues to run without cycling off could induce ‘superheat’ I do believe.
If that is what you meant in your original post, then that is definitely a problem in and of itself. However, I do not believe you would be able to prevent or reverse that condition by setting the temperature knob to Max-Hot while the A/C is engaged. So I don’t think it is significant that your heater does not have an effect on this freezing condition, as that is actually how the system is designed (the air goes through the evaporator and is cooled down before it is routed through the heater core to get heated up).
But let’s not get too far ahead of ourselves just yet… There are a couple more details I think are missing and should be filled in if possible:
1) Can you hear the clutch on the A/C compressor engage when the engine is running and you turn the A/C on?
2) If so, then you are saying after that, once engaged, you never hear the clutch disengage until the engine is turned off, correct?
3) You said you had a scan tool capable of real-time data display. Can you use that to check the high-side PSI numbers for the A/C system when it is behaving like this?
4) If so, what is the pressure on the high side? Is that output value a steady PSI number, or is it continually climbing as the compressor continues to run?
5) What is the service history of the A/C system in the car? Unknown, never serviced, serviced but by a certified tech, etc.?
6) Are you able to get your hand back behind the engine so that you can use your fingers on one hand to take the relative temperature of the 2 refrigerant lines coming out of/going into the firewall (on their way to/from the evaporator)?
7) If so, what are the lines’ relative temps (relative to each other) after the car is running and the system has been on for a while, continually cooling (or trying to)?
That last little manual test of the temperature of the 2 a/c lines in relation to each other (both about the same, one colder than the other, one hotter than the other is actually a very informative test with respect to how the system’s health is overall. If both are about the same temp, it is healthy; if one is colder than the other, the system is NOT healthy, but what ails it is a whole separate discussion, so let’s focus on one thing at a time…
If you are able to provide some clarity/more details on the issues I laid out above, I think we will be better able to troubleshoot from there (or realize it is beyond our capabilities to diagnose). Either one is preferred to the current status, I'm sure :wink3:
Plus, those members who are certified techs and such that could help out here might be more inclined to chime in once we’ve got a more clear picture painted of the situation :SM002:
nuke