04 vue A/C question

[windrider265]

My question is does anyone know what could cause my air conditioner to blow less cool air when siting at an redlight or coasting to stop. When the Rpms drop below 2 the air stops cooling dramatically. Has never done this before. I had saturn test it and said they found an shredder valve broken and they replaced it then recharged the system with no other leaks (under warranty) proclaiming it was fixed. However it was a cool day and air was not needed so when tested it it did blow cold. Any ideas. Summer is on the horizion and I dont want to have to rev my engine at a red light to keep it cool or in drive thrus either :cry: .

Thanks

[fdryer]

Welcome to SaturnFans! Hope you have a safe holiday and that you can use your a/c through this long weekend. As to your post it seems confusing as to whether the problem exists or if it was solved by the replacement of the schrader valve, the same valve on your tires, on the a/c lines. If you are still having a/c cooling problems at a stop then Saturn service didn't fix it. Simply return the car at the earliest explaining to the service department that cooling is lost at idle and that this never occurred before the a/c required repair and insist on the fact that your car does not work as they would have you believe. There may be more inherent problems and hesitating now won't get to the bottom of your dilemma unless you contact Saturn service. They may be expecting a call from you as a/c repairs may require a second trip, the time in your possession to use the a/c for owner evaluation, and for you to notice any differences before and after this recent service. Hope this helps.

[Chazberry]

My question is does anyone know what could cause my air conditioner to blow less cool air when siting at an redlight or coasting to stop.

Coincidentally, I just started having the same problem on my '03. It was around 90° here on Fri., I'm sitting in traffic and the A/C just ain't cutting the mustard. Even at highway speed, it ain't chillin' like it used to. Today I check to see if I'm low on refrigerant, but the suction pressure is showing good -around 40 psi. I'm way out of warranty - hopefully you can get some satisfaction from Saturn.

[fdryer]

At what idling speed were you measuring the pressure on the low side? If you are not familiar with the temperature/pressure relationship of R134a refrigerant then stating 40 psi is presumed to be measured at idle which makes your system low on refrigerant. In addition, your initial assessment would be incorrect if you were measuring the pressures at idling speed; most vehicle hi/lo pressures measured with a/c gauges are done at 1200-1500 rpm and not at idling speed. You'll quickly see this as a lower pressure reading displayed at the higher rpm range to verify my guess that your system is low on refrigerant. This little bit of information is another reason why a/c isn't a casual DIY repair. Chances are that a leak has developed with only a 4yr old car. Perhaps refilling with replacement R134a w/dye will accomplish two tasks; having a/c back and more importantly the dye will leave a marker wherever the leak occurred.

[Ritz]

At what idling speed were you measuring the pressure on the low side? If you are not familiar with the temperature/pressure relationship of R134a refrigerant then stating 40 psi is presumed to be measured at idle which makes your system low on refrigerant. In addition, your initial assessment would be incorrect if you were measuring the pressures at idling speed; most vehicle hi/lo pressures measured with a/c gauges are done at 1200-1500 rpm and not at idling speed. You'll quickly see this as a lower pressure reading displayed at the higher rpm range to verify my guess that your system is low on refrigerant. This little bit of information is another reason why a/c isn't a casual DIY repair. Chances are that a leak has developed with only a 4yr old car. Perhaps refilling with replacement R134a w/dye will accomplish two tasks; having a/c back and more importantly the dye will leave a marker wherever the leak occurred.

It would also be instructive to know:

the high side pressure
the temperature outside when it was measured
the temperature of the A/C coming from the vents when on "max"

I agree that 40psi at idle is probably a bit low. But it's hard to say without knowing all the details. A/C systems have multiple points of failure, even with a full charge of refrigerant.

Cheers,

[Chazberry]

At what idling speed were you measuring the pressure on the low side?

Thanks for the tips. I WAS looking at the idle pressure. I only have a cheapo recharging kit, so I'm only seeing the suction pressure, which dropped into the "Low" zone at 1500 rpm. I added 12 oz. of 134a with the UV leak detector - it can probably take another 12 oz. I'm now hoping I've had a slow leak for a long time and it isn't my compressor seal that's going south already.

[fdryer]

If its any consolation, its not likely your compressor seal is worn as it would be obvious at the front of the compressor where the clutch/belt resides; there will be an obvious oil/dirt build-up surrounding this area. Motor oil doesn't normally deposit there, only refrigerant oil leaking past the front seal will while refrigerant evaporates into the air if the seal is leaking. :cool:

[Ritz]

Thanks for the tips. I WAS looking at the idle pressure. I only have a cheapo recharging kit, so I'm only seeing the suction pressure, which dropped into the "Low" zone at 1500 rpm. I added 12 oz. of 134a with the UV leak detector - it can probably take another 12 oz. I'm now hoping I've had a slow leak for a long time and it isn't my compressor seal that's going south already.

I would only use that leak seal stuff as a last resort (most of the aftermarket stuff has "seal conditioner" and "leak stop" added). Did the air get cooler when you added the extra 134a? Is the compressor short cycling (going on and off every few seconds)?

Best,

[Chazberry]

I would only use that leak seal stuff as a last resort (most of the aftermarket stuff has "seal conditioner" and "leak stop" added). Did the air get cooler when you added the extra 134a? Is the compressor short cycling (going on and off every few seconds)?

I only added a can of DuPont Suva plus Leak Detector - no sealer.
I may still be getting some short cycling - I have watch more closely. I also have to find my thermometer so I can check the discharge air temp.
Thanks for the suggestions.

[windrider265]

Sorry took so long. Thanks for the suggestions. I meant that the air blowes normal ie very cold when the engine is reved around 2 rpms. if sitting and idle or coasting very noticable decrease in coolness of air, never did this before even in the 100 degree last year. I talked the saturn dealer and they said bring it by and the would check the whole system. only prob is saturn is in near by city (45 mins) away. So i have to wait intil have time to take it. Again thanks for all the help. I took the vue in for several things the a/c happened 2 days before the service. I had the trans 50 k service new brakes in front and new radio along with seat back of passenger side. Love the extendend warranty.:)