Suddenly the AC on my SSB roadster started blowing hot after the engine warms up. The AC system is tested and working perfectly so I went to the ever fickle heater control valve assembly (again). After replacing the heater control valve assembly TWICE, I discovered that there is no power getting to that three prong connector that plugs into the heater control valve assembly (no wonder the valves are not working . . . DUH!). I checked all the climate control fuses and then went on to check every fuse in the car. ALL of the fuses in the entire car are good. I researched the 2005 Crossfire SRT6 service manual but dealing with electrical circuits is at the very low end of my ability scale (it may as well be presented in an alien language).

Can someone point me toward what to check as to why there would be no power getting to the heater control valve connector when the fuse in that circuit is good?

Also (coincidentally or maybe possibly related) My outside ambient temperature circuit started reading -36 F at about the same time. I swapped the sensor to another known working car and that sensor is working. I put another known working sensor into non-working car and it again still reads -36 F. I don't find any circuit referenced that powers the ambient outside temperature sensor? What do you think?

Thanks for sharing your experience and expertise . . .

Bob Davis (Red Dog)

 

I have a limited knowledge in this area, but I think the default position of those valves is open and that means hot air. These are controlled by the left and right rolling dial on the left and right sides of the AC control panel. (red/blue dials)
If you have a spare one you can swap it out, it is held in with 2 screws and 2 snaps on the mounting plate. There is a repair of the control on this forum which says that the circuit board comes loose and makes poor contact with a socket. I opened up the unit and could not see how it could come apart enough to affect the workings of the unit, but the OP of the thread said it was the way to repair his problem and so hopefully it will solve yours. CLICK
GreyGhost has played around in this area and knows more than I.

 

Thanks Dave, I'll pull the AC control module out and take a look at it . . .

 

The ambient temp. sensor is powered thur the instrument cluster. The outside sensor itself has a variable resistor in it ,that has probably gone bad.

 

Hi Steve, The sensor itself has been tested and is working fine. The problem has to be in the wiring between the instrument cluster and the sensor connector. Guess I'll need to pull the instrument cluster to check (and that won't be happening anytime soon). First priority needs to be getting the AC working again.

 

PM GG as he has studied this area for a problem he had.
I am assuming that the compressor is working properly.

 

Will do on contacting GG . . . Yes the AC system (including the compressor) is working perfectly. Just can't get through the hot air from the "open" heater control valves that are not getting power.

 

Bob, I have never messed with either system you are having issues with. But the first thing that comes to mind is what is common in these two systems, per wiring? Grounds, etc...?

James

 

Bob, check your PM's, hope you can solve it using the .pdf that Dave referenced!

.

 

UPDATE: With the help of forum members, we have determined the problem to be within the climate control head unit not sending power to the heater control valves. I have ordered a gently used climate control head from E-Bay and will swap it out when it arrives. If that solves the problem I will then take apart the bad unit to see what has failed (but presume the problem is with faulty connections between the circuit boards as shown in the forum link provided by onehundred80). Thanks for the responses and assistance. I'll let you know how this turns out. Then I'll try to fix the problem with the ambient outside air temperature.
Bob Davis (Red Dog)

 

Well the section starts on page 24-9 in the '05 manual. Next the main A/C Heater Control Module connector looks like a 29 pin , the three pin connectors are from sensors and should not have 12v on them.


The main schematic for the HVAC module is on page 24-60 with power from fuses 33, 35 and 37 (36 and 15 run other HVAC components. Ground is on pin 12.


That said if the fan is working properly I doubt that the problem is electrical If you look at the diagram on page 24-67 you see a "coolant circulation valve" (6) that controls the heat by varying the water flow through the heater core. This is unusual in modern cars since response is so slow. The systems I am used to parallel the AC and heater using air blend doors to control heat.


So in a case where the controls work but is always on full hot, I would look at the circulation valve first and not the module.


This is a little confusing since page 24-74 refers to "blend doors" and never mentions the coolant valve while the diagram on page 24-63 shows the heater and AC in series and no temperature blend doors.


Guess someone who has taken one apart needs to chime in because the service manual does not make sense.

 

There is no power at the valve.

 

UPDATE 12/23/17 - I replaced the climate control head and still do not have any power getting to the heater control valves (the hot / cold wheels are supposed to sent a power signal to the heater control valves - I've watched it work on my other two Crossfires). Replacing the climate control head DID fix the erratic blower motor speed though so that saves me trying to fix the erratic blower motor speed by putting in a new blower motor resistor . . .

Can someone please tell me what fused circuit feeds the hot / cold wheels on the climate control head and then sends power to the heater control valves? I've checked / double checked and triple checked every fuse that is supposed to have anything to do with the climate control (ie 15, 33, 34, 37) and all those circuits seem good. Any suggestions??

 

Bob, says here that fuse #15 feeds those valves, along with the REST pump :
I 'think' a solid ground from the control module pin = NO flow, and open relaxes the valve and allows flow.

 

Do you actually have power at pin #2(?) on the valve connector? If you do and you should as it comes straight from the fuse then it is a grounding problem somewhere.
That is what I see with my very limited knowledge of sparky stuff. A meter between a good earth and pin #2 (?) should give a reading of 12 volts.

 

The pinout on the valve connector :

( try just disconnecting the valve plug and see if she heats up )

 

OK guys . . . Thanks for the additional information. I went to one of my working cars and pulled fuse #15. That DID cut the power to the heater control valve connector so that circuit is where my problem lies. I'll investigate it further tomorrow.

Quote:

Originally Posted by onehundred80

Do you actually have power at pin #2(?) on the valve connector? If you do and you should as it comes straight from the fuse then it is a grounding problem somewhere.
That is what I see with my very limited knowledge of sparky stuff. A meter between a good earth and pin #2 (?) should give a reading of 12 volts.

I'll check that tomorrow Dave. I understand . . .
Also, I took my original climate control head and just did the mod / fix shown on the link that Dave provided . . . CLICK
I'll swap that head back in tomorrow and see if there is any change. Will keep you advised. THANKS for your assistance.
Bob Davis (Red Dog)

 

UPDATE 12/24/17: I did more diagnostic tests . . . Made some progress but still not working. When I put the OEM modded climate control head back it, the fan speed works perfectly now. So I believe that the erratic fan problem that most Crossfires eventually experience seems to be more related to loose contacts within the climate control head than to the resistor on the blower fan. THANKS to the original poster for the write up on this DIY fix here and THANKS to Dave (onehundred80) for making the PDF:

CLICK

I tested the connection to the heater control valves and I confirmed NO POWER is getting to the three prong connector (the #2 female pin on the connector is not receiving power signal from that circuit). I verified my tests on the other two working cars just to be sure my test was being done correctly. Accordingly it would not seem to be a ground issue but rather the test points to some problem with the power in the fuse #15 circuit. So on this image provided by George, it shows the #2 center pin as "fused B(+). What does that mean? Might there be an inline fuse besides the 5A #15 fuse?

Also, the REST pump also runs / gets power from that #15 fused circuit. Where can I find / check that pump to see if it's running / getting power from the circuit?

Any new thoughts??

Thanks again for sharing your expertise . . .
Bob Davis (Red Dog)

 

I would take that to mean #2 is constantly hot and ground is applied as called for. I would try jumping 12v power to #2 and see if everything functions.

 

The REST pump on mine ( an NA ) is down where the intercooler pump is on the SRT6, I don't know where they put it on the 6.
You test the REST pump by pressing the REST button with the ignition switch off.
There are NO inline fuses in these cars ( from the factory ).

Did you meter the fuse ? Did you check the fuse cavity for 12v ?