My problem is typical. My A/C is not cooling as much as it used to. First I thought the refridgerant is low so I bought a gauge and checked it. I measured on the low side, and surprisingly the reading was not low, but rather it was a little bit higher than the normal range even after I ran the system on max cooling for 5 minutes. When I increased the rpm the pressure went down a little bit to the high end of the normal range, but climbed back up at idle.

Does anybody have any idea what the problem could be? Maybe the compressor? How can I be sure of this, since I do not want to spend a bunch if I can avoid it. Where does one buy an A/C compressor besides the dealer? And for how much?

Thanks

 

whoa slow down! I had a similar situation. all i did was leak a little 134a outta the low side and all is well. an overcharged system is as bad as a undercharge one. does your compressor click on and off? low side should be around 30 psi on a 85-90 degree day

jeff

 

If you never charged the system before, it could be general compressor decline. Unfortunately, you need a set of 75 buck gauges or an a/c shop to confirm that. Other causes include: expansion valve faulty, air not being entirely shut off from the heater core (meaning your air is heated and cooled, resulting in a lukewarm output), but generally it's the result of incorrect charge level or a faulty compressor.

It's up to the individual whether to spend the money, but many times a/c work is a "do it right first time" type of application. Which generally means you have to take it to an a/c shop and pay the dollars. Personally, I hate not doing work on my own car and for that reason have not had it fixed this year. Mine only works well above 40 mph.

 

Like davey6693 said, AC work is best left to professionals. And systems generally get less efficient with age. Having said that, there are a few things you can do. First I would check the actual temperature coming out of the vents compared to ambient air temp. It's getting hotter out, so AC systems won't seem to get as cold. Most car AC's will cool a maximum of 40*F on max AC. If it is 110, the best you'll probably see is 70, and that's on a perfectly fine operating system. This varies on relative humidity, also. See page HA-33 of FSM for the chart.
Also, the compressor won't operate correctly if overcharged. Check the FSM (page HA-33) for specs on pressure with varying ambient temps. Ours ranges from 24 psi at 68*F to 30 psi at 104*F (all with 50-70% relative humidity).
Make sure your fans operate properly. BOTH should be on when AC is on. You'd know if something was wrong with one at idle. You'd get hot air (personal knowledge).
Clean off your condensor of all leaves, bugs, furry animals, etc... This will allow maximum airflow.
If it is still not operating properly, I'd let a professional check it.

Dave

 

Thank you for your input. I was thinking that the compressor is at fault since I own the car for 2 years now, the A/C has never been charged, it used to work OK, but now it does not anymore.
There is something else I noticed: The compressor does not cycle at all. It is on from the moment I turn it on on the dash and turns off only when I turn the A/C off. Shouldn't it cycle? Does this confim a fault with the compressor or does this indicate something else?

Thank you guys for your comments.

 

The Maxima compressor (Calsonic) does not cycle on and off during normal operation, unlike many other compressors. It has a swash plate design that changes piston stroke in response to the cooling demand. This means that although the compressor is running the whole time, the rate at which it is working is variable. In actual fact, if it does cycle, then you've got a problem, most likely too high or too low a charge.

If your compressor does indeed require replacement, then you can at least get a rebuilt unit for a good price from Auto A/C Import Rebuilders. Then you can have an a/c shop empty your current system, install the new unit then vacuum down and recharge with R-134a.

Note that I haven't done business with these guys (but probably will do in the future).

 

About time somebody set that straight!

 

Does anyone have any experience with these Maxi Cool A/C Booster refridgerant additives? (supposedly they contain lubricant, a/c cleaner, o-ring conditioner and leak tester/sealer, and they are $8 a can at Autozone) It boosts the performance of high milage systems??? It is worth the 8 bucks just to try, but I do not want it doing any harm, like clog the expansion valve.