AboutTodd Puccio Expertise General auto repair,electical issues,driveability issues,anti-lock brakes,SIR systems,HVAC,engine performance,Gm spacific. I have worked at my current dealseship since the 1990 model year anything much older than that I have limited exposure to. I do not have very much transmission experience so those question you may want to ask of another expert. When you send me a question let me know the exact make/model/engine and year for the car or suv you have it makes it easier to answer the questions that way.
Experience Experience in the area:I have been employed by the same Gm dealer for 18 years and and a ASE master technician. I work at a Pontiac and GMC truck store. Served a a lead technician when dealership was on a team system.
I just recently moved to a Buick,Hummer,Saab Store when my franschise was purchased by this dealership.
Organazations: ASE master techncian
Education/Credentials:High school diploma,2 year vocational school degree
2 year college degree. Associates degree in applied scineces (auto technology)Awards and Honors: GMC master techncian
Question QUESTION: I've got a 1995 firebird formula, that I just replaced the compressor line and took it to a shop to have it evacuated, pressure tested and charged. The shop told me they were never able to get the compressor to engage, and it was engaging before. I've tested the power plug and it pushes over 13 volts to the compressor when the car is running, but the compressor still doesn't turn. The pressure sensor indicates that there is 50psi in the a/c system when the tempurature is about 66 degrees F. After several minutes of running the car, the computer cuts power to the compressor and doesn't turn it back on until the car is shut off and restarted. Also, both cooling fans kick on and won't shut off until the car is. I'm wondering if the compressor isn't kicking on due to too much refrigerant in the system, if that's really the case, or if the compressor has been damaged? Any suggestions would be appreciated since I don't have the money to have a shop do all the repair work.
ANSWER: Hi Brian:
If there were too much refrigerent in the system the static pressure would be higher then what you stated. I would hook up a halogen light bulb across compressor connector start the car up and turn on the a/c the halogen bulb should light up BRIGHT if not you have high resistance in the compressor power or ground circuit. just because you have 13V at the copmpressor doesn't mean the ground circuit is good of that the wires can handle the amperage the cluth need to engauge. If the light bulb does light up bright the issue is with the clutch on the compressor either the coil is bad for the clutch or the gap between the clutch and the hub is to wide. Good luck :)
---------- FOLLOW-UP ----------
QUESTION: Thanks for the input. What should the resistance be? I do have and ohm meter and can measure that. I just put my test light on the plug, and it does light up bright. I also grounded it to the battery and it appeard just as bright. So, if I'm right in my thinking, that would suggest the resistance is low. I'm conserned that maybe I'm not getting a solid connection on the compressor, so I was thinking about running some jumper pins from the power plug into the compressor socket before I pull the mounting bolts to move the compressor foward and rotate slightly to make the socket much easier to access.
Answer From what you told me It sounds like you have a good power feed to the compressor and a good ground as well. so that would indicate an issue with the compressor like I stated before either the coil in the clutch is bad or the air bad on the hub is to wide. I would say the resistance of the coil should be around 25 ohms But I can't say for sure. If you have an ohm meter there should be some reistance across the oil and not an open ckt where the meter would read "OL"
