'95 A/C Compressor Loading

[compyelc4]

I've noticed before that I can feel the A/C compressor kick in while at interstate speeds. It feels like it very slightly bogs the engine for a micro-second when the A/C clutch cycles. Also today, heading into a strong headwind at 70mph on an 80 degree F day the A/C cycling was particularly noticeable and dropped my mpg at a stead-state speed by 3-4 mpg. Is this considered normal for a late model great-running LT1 with 40,000 miles and a 3.07 rear end? Seems weird to me. The only other car I have ever experience this with was my old '63 Chevy Bellair with a 165hp I-6 and a huge-mutha aftermarket A/C compressor.

BTW my A/C has not been charged since new from factory and it is about the coldest R-34a A/C I've ever felt. Much colder than my '07 and later cars! It has leaked no oil, and apparently it still has a great charge. Any ideas?

 

[rlg]

First thing I would do is to check for any codes

 

[Robertwav1]

I say you shouldn't be able to tell the AC comp engaging with the LT-1 engine. This is about the only car I ever had where you can't tell the difference with the AC on or off. Too much gas in the system could cause your problem or a restriction in the system. If it's cycling a lot could be going off on high head. I'd check that first. I would think if you had a bearing going bad you would hear it. A real hot day would be a better test. R-134a is known for coagulating and if it was a changeover from 12 and was not done correctly (oil has to be changed at least three times) restriction in the system from incompatibility with oils always happens in time. Even 134a virgin systems don't hold up like the older 12's.

 

[compyelc4]

Thanks for the reply Robert. Regarding R-12 versus 134A do you know what was in my system originally because it has never been changed. Is a '95 an R-12 system then?

 

[compyelc4]

Further Robert.......... I have an '07 Nissan Altima and a '99 Pontiac GrandAm GT. The Altima is impossible to detect. I can only very slightly detect the cycle in the GT.

 

[Robertwav1]

Well...the 94 was 12, knowing from working on a few. The 95 was probably the change over to 134a, although there could be a few made with 12, maybe the earlier ones, I'm not sure. I haven't seen any 95's with 12. Although the 134a does a good job cooling I just see more issues with this and cap tubes have a tendency to clog up causing restriction. What ya need to do (on a hot day) gauges will tell you what the head pressure is and could be the problem you are experiencing noticing the engaging of the compressor. Do yourself a favor and have someone do that if that's not your field. The diags should not take long at all. At least you will know what it is that has to be done. It should definitely not put a drag on that much HP.