Normal A/C operation ???

[The Critic]

At 70 mph, the air blowing out of the vents is ice cold. Great. Now at 30-40 mph, the air barely seems cold. I didn't measure it with a thermometer, but I'd guess that it'd be at least 50 degrees. In stop-n-go traffic, it almost seems warm.

The car in question is a 96 Saturn SL2 w/104,000 miles, and I've never any A/C work done on it before.

I'm tempted to go to Target and pick up one of these things for $14.99 before I shell out $110 to have my trusted A/C guy do a evacuate and recharge: Glacier Ice Recharge Kit

So, is there really something wrong with my system or is this normal A/C operation?

Thanks.

 

[psudaytona]

In the crown vic I just picked up, the air is ice cold to the same degree at any speed/rpm range. Its possible its a bit low on charge and when the engine speeds up, it also speeds up the compressor making it a bit colder.

 

[adam123]

Most likely In need of a recharge, Could also be bugs and debri blocking the flow of air at low speeds since it's much more dependant on your engine fan to provide adequate airflow. Most likely its just low on Refrigerate tho.

 

[punisher]

Check the cooling fan/condenser fan first and go from there.

 

[The Critic]

Thanks, I'll go pick-up a can of that stuff and hose out the condenser area.

 

[Chris142]

Quote:

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Check the cooling fan/condenser fan first and go from there.

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X2. If the fan isn't coming on or the condensor is dirty the AC won't work well. Make sure the fan is on when the AC is turned on.

 

[kgb007stb]

All of my Saturns run in the low 30’s on the low side at idle ~700-800 rpms. Make sure that when you fill your low side, DO NOT squeeze the trigger and blast the system. I was warned by not doing so by a trusted AC mechanic who worked on ACs for 40 years. Supposedly you create such an imbalance in the system that you blow gaskets or have a major failure, even if the pressure is within specs. Always use a valve body with an inline gauge to ensure a slow and steady fill, good luck

 

[The Critic]

Quote:

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Quote:

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Check the cooling fan/condenser fan first and go from there.

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X2. If the fan isn't coming on or the condensor is dirty the AC won't work well. Make sure the fan is on when the AC is turned on.

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Hmm, just checked it...looks pretty clean to me. Fan works great.

Quote:

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All of my Saturns run in the low 30’s on the low side at idle ~700-800 rpms. Make sure that when you fill your low side, DO NOT squeeze the trigger and blast the system.

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OK, so just squeeze very slowly?

 

[punisher]

Main thing is do not feed liquid refrigerant into the low side fitting on a system while it is running. As long as you are feeding gas to it, charge away. Liquids aren't compressable, and compressors can fail when trying to do the impossible. Industry term is "slugging" a compressor.

 

[kgb007stb]

I think punisher is onto something, I wonder if the slow recharge rate is due to letting the liquid vaporize on the low pressure side once inside the AC. Yeah squeeze gently, always with an inline pressure gauge so you can monitor the pressure. It will be hard to achieve a constant flow with the squeeze mechanisms, so if you blast it, stop and give it some time to stabilize before re-charging. The $3 valve controls the flow much better and I personally stay away from the squeeze mechanisms. The refill bottle itself is capable of producing 100-120 PSI easily depending on the ambient temperature. I usually try to feed the system no more than 10 PSI above what’s in the system, just my thing, but it has never failed.

You can decide how much to put into the system, I could never find a service manual which would specify the correct “low side” pressure. I decided on the 30’s as a safe way as this reading also changes with ambient temperature, I usually do mine around 70-80F so that I know what to expect from the system, but it also gives me some reserve in case I over do it.

I have an all black car, but even when we had the triple digits, that thing is ice cold. Even I who like cooler weather have to turn in down after 10-15 mins on the highway, give it a try and let us know how you came out. I’ll be doing some experimentations on my Saturn this weekend as well.

 

[The Critic]

Went ahead and bought a Glacier Ice GL-1 kit for $15. It was about 75-80 degrees outside yesterday morning (well, around 10 am). I figured that 3-4oz loss after twelve years wouldn't be unreasonable, so I added about that amount.

Then, I ran the system for 10-15 min on max (in recirculation mode) with the car idling. I sat in the car for the entire time after adding the refrigerant and the air coming out of the vents was absolutely frigid. I was shivering. After the full 15 minutes, I checked the pressure and it read about 28-29psi @ 900RPM according to the included gauge.

At 60 mph on the highway with outside temps in the low 90s, the air coming out of the vents fairly cold. During low-speed driving, air was cool relative to the outside. I think there was a slight but noticeable improvement in cooling during the low-speed/stop-n-go driving conditions compared to before, but I may just be dreaming.

 

[steveh]

Wow I guess it works better then PP. LOL!!!!

 

[mechtech2]

Ford tests show around 6 ounces of refrigerant loss per year, on average. The tiny molecules go right through the rubber lines, and out the seals - lines and compressor.
A low side auto parts store kit is great - get one that you can reuse on other cans, and other cars.
Put your AC on Max, fan on full, and windows open. Keep the engine at 1,500 RPM or so. Let it stabilize for a minute or so, and only read the low side when the compressor is engaged [they usually cycle on and off].
Depending on outside temps, it should read 30-35. More is not better.
But your low speed cooling loss sounds like an airflow problem with your condenser, and possibly a fan issue.
You have to get the AC pressure correct, first.
Make sure your fan are engaging, and the condenser is free of dirt, leaves, and bugs. Take it easy cleaning it, as it is kinda fragile.

 

[kgb007stb]

I say leave it as is, if not satisfied take it to your trusted mechanic to either perform a complete evacuation and refill or suggest other possibilities.

Took an afternoon drive to Fry’s on Northridge Blvd, holy smokes was it hot today, and the AC blew ice cold, I understand nothing like having a good functioning AC.