Air Condition causing serious performance issues
#1
Cruising
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Air Condition causing serious performance issues
My 72 vette has a crate 350 engine with all new A/C components. The previous owner put all the hardware in it and told me when I bought it that the a/c worked but seemed to have a leak and needed to be looked-over.
So I had it serviced this week, which included vaccuum, r134 fill-up, and a new belt had to be put on since there was no belt on it before.
The first drive out I noticed while idling at a stop sign with the a/c on (tried "Max" and "Norm" settings) that the battery gauge was going nuts (needle was jumping around over and under 0).
I had to hold a bit of pressure on the gas pedal to keep the engine running - it seemed likely to quit on me while idling, even after being warmed up.
When actually out on the road, if I was just cruising the battery meter was stable, but I noticed a regular hesitation in the car, which, if I didn't know any better, I'd say felt like minor engine braking at regular intervals. If I switched off the a/c, the car ran smooth -
So -- I know running your a/c will put constraints on the engine but should it be doing all this?
My thoughts are maybe the belt the tech put on isn't right somehow, or maybe I have a problem with my electrical system...?
Any ideas on where to start troubleshooting this would be appreciated!
So I had it serviced this week, which included vaccuum, r134 fill-up, and a new belt had to be put on since there was no belt on it before.
The first drive out I noticed while idling at a stop sign with the a/c on (tried "Max" and "Norm" settings) that the battery gauge was going nuts (needle was jumping around over and under 0).
I had to hold a bit of pressure on the gas pedal to keep the engine running - it seemed likely to quit on me while idling, even after being warmed up.
When actually out on the road, if I was just cruising the battery meter was stable, but I noticed a regular hesitation in the car, which, if I didn't know any better, I'd say felt like minor engine braking at regular intervals. If I switched off the a/c, the car ran smooth -
So -- I know running your a/c will put constraints on the engine but should it be doing all this?
My thoughts are maybe the belt the tech put on isn't right somehow, or maybe I have a problem with my electrical system...?
Any ideas on where to start troubleshooting this would be appreciated!
#3
The first drive out I noticed while idling at a stop sign with the a/c on (tried "Max" and "Norm" settings) that the battery gauge was going nuts (needle was jumping around over and under 0).
When actually out on the road, if I was just cruising the battery meter was stable.
#5
Melting Slicks
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St. Jude Donor '08
If you have the original A6 compressor, then I think it's absolutely normal to put a ton of load on the engine (I heard that it would take up to 30 HP!!). Did you flush clean all the A/C components and put a fresh R134a compatible refrigerant oil in there? .. if you put a R134a and mixed it with a non R134a compatible oil then chances are getting everything siezed up after a while (tell me how I know!).
#7
Burning Brakes
Sounds like you need an idle compensating solenoid. If you have the original carb it should be built into the carb. If not you can buy on from one of the vendors but they are expensive. It kicks up the idle when the A/C is on due to the extra load.
Make sure your car is tuned correctly and you have no vacuum leaks when in A/C mode. If the idle is seriously low your alternator can't put out enough and that's why the gauge is all fluctuating all over the place.
http://www.parts123.com/parts123/yb.dll?parta~partsort
Make sure your car is tuned correctly and you have no vacuum leaks when in A/C mode. If the idle is seriously low your alternator can't put out enough and that's why the gauge is all fluctuating all over the place.
http://www.parts123.com/parts123/yb.dll?parta~partsort
#8
Intermediate
Member Since: Sep 2007
Location: central coast CA
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I just finished rebuilding the a/c system recently in my '72 using all new parts. (sanden rear exit compressor,evaporator,drier,expansion valve,POA valve,parallel flow condenser, hoses, fittings and a new a/c wiring harness.) If you're using a stock POA valve the compressor should not be cycling on and off. I also found a idle solenoid at auto zone(part#E403) for $26.99. I still had the old bracket laying around so I wired the solenoid to come on whenever the a/c is turned on. In my case I don't think I really needed the solenoid because using the sanden compressor the idle only drops 100 rpms when I switch on the a/c. The first place to start would be to see which kind of POA valve the previous owner installed. Is it the stock one or one of the updated cycling POA valves? As I understand it, the A6 compressor does not take well to being cycled on and off. When I turn on my a/c, the compressor runs until I turn the a/c off. I don't know if this answered any of your questions but hope it helps.