New to the forum so if this is not in the correct area please let me know. To get started Im working on a 97 bonneville with climate control. Early this spring the ac compressor was slipping and lots of metal shavings, so replaced ac compressor and assc. hardware. Worked great up until about a month ago. The check engine light came on and the ac also stopped working about this time. Well this last weekend I finally had a chance to trouble shoot the cel and replaced the engine temp sensor. Thanks to this site it directed me right were to go. My cel is now out, the temp gauge now shows about 200 degree temp, before just stayed at 170. My problem is now the ac will come on when ever it wants, and by this I mean I push ac button the fan kicks up but the clutch will not always engage. Also you can be driven and have it turned to 60 degrees in manual mode and the heat kicks in, like the full 90 degrees has been pushed. The blower motor comes on after 10 seconds to 20 min of driven. At no given point while driven it will start to blow ice cold air and then the compressor will kick out, sometimes blower stops. I can change the air position to floor, vents or defrost with out issues. I have checked pressure on ac side and it is right were it needs to be. I am auto literate, but this is being a pita..Thanks to anyone that be able to help...

I forgot to mention that I did check voltage to the blower motor and it read 1.4v and as I turned it up it went to 1.9 volts and varied by about 2 tenths of a volt. Let it sit for about 2 min and the voltage spiked to 11.98 volts and as I turned the speed down it dropped by about 2 volts per speed. So its not getting the signal to start, same as ac compressor. Checked grounds and they all seem good with no green and good connection at termination side..

you saying you checked this?
https://www.gmforum.com/electrical-1...4/#post1563231

Thanks for the reply. After reading your post I went outside and pulled the carpet back on the drivers side. All I can find is a cable with black loom around it running in between door and the seat. From there it travels along the edge to under the dash. It does pass under a black cover under the dash but that looks like its just a cable tray..

Not sure how to edit on this site. After reading your reply again I knew what you were talking about. Went back out and cut the tape and checked ground buss. Looks just like the day they put it in..

i dont have good diagrams of the system, but i do have that in my car. i know the compressor control is from the pcm, pcm gets inputs from pressure sensor & hvac control. a good scan tool can tell if the controller is requesting a/c or whatever if it where me i would talk to a local shop that has the ability. i havent had to replace my controller but im guessing its probably too expensive to shotgun

[QUOTE=deder_2;1565835] I forgot to mention that I did check voltage to the blower motor and it read 1.4v and as I turned it up it went to 1.9 volts and varied by about 2 tenths of a volt. Let it sit for about 2 min and the voltage spiked to 11.98 volts and as I turned the speed down it dropped by about 2 volts per speed QUOTE]

Is this a car with automatic control for the fan? Or do you have manual fan speeds that use the resistor for the lower 3 speeds and a HI speed circuit that is separate?

What do you get when you run a fused battery line to the heater blower connection directly (and supply it with a ground connection).

I would suspect your BCM if it'* the automatic control.

Again the blower stopping and wandering speeds sounds like the BCM (blower control module) which varies the blower speed to adapt with the requests of the programmer.

The changing temperatures sounds suspiciously like the actuators that move the blend doors. I do not know for sure that you have two actuators with the automatic system... does your car have separate control for the passenger temperature?

The electric actuators can slip on the hub internally. The result is the outside arm that moves the metal link to the blend door doesn't correctly move that door. The computer has lost its index marks for the positions of the door in its memory because of the slipping. So when the programmer turns on, it moves the door to full hot (or cold) and sees if it gets a resulting temperature change in the temp sensor. Then it goes the other way to find what actuator position gives the full movement in the other direction. If there'* slipping..., then the computer is lost.

Try taking off the hush panel and the glovebox door to see more of the movement. You can watch with the engine off while you have the key ON and change the settings of temperature if you have the automatic system.

[quote=imidazol97;1565855]Yes it is the auto control, but it doesnt matter what mode its in, auto or manual. The display never blinks or shows a code-I can change the temp,direction of air flow and fan speed-I have no voltage-I just sit and watch for a bit, voltage jump to correct volts and fan starts up..Where is the bcm?

Update: Took over to my cousins house( brought two ribeye'* with) and asked if I could use him and his equipment. So we hooked up the computer and took a look at what was happening. The computer was getting the signal for ac and the motor jumped by 200 rpms for the load. Ac never kicked in. Also took a look and the blower was not getting voltage. So we assmued two different problems. Started with the ac. High side sensor was only reading 1.3 volts and low side was zero. Went to disconnect low side switch and thats when I heard a click from up by the dash on the outside and the clutch engaged and the fan started working. Now cant make fail. Is there a common ground between the blower module, ac compressor and the digital control? I have no diagram so shooting from the hip here..Any help would be great..